I am currently faced with the project of re-wiring an old, concrete block dairy barn/shop, which also supplies power to the secondary water well pump. This is an old farm house. The wiring to the dairy barn has been run underground ( a single 2 wire system) to the dairy barn and must be replaced due to rodent damage. Currently, there is a 220V/30 amp circuit feeding the water well, and a 110V circuit for minimal lighting/outlets. I am intending to dig a trench and bury the underground EMT grade tubing with the upgraded wiring necessary for new equipment.
The new wiring will be 3 wire for 110V and there will also be two seperate circuits for 220V. One 220V will have to be 50 amps for the welding machine, and one will be 30 amp for the Water well. There will also be 5 each, 4 foot fluorescent light fixtures, and 8 20 amp plug outlets (110V). There will be one internal breaker box in the dairy barn for all electrical components. All above ground wiring and outlets will be run through steel EMT conduit with steel housing boxes, to rodent proof it.
My questions are as follows:
1.) The feed line is coming from the Farm house approximately 100 - 130 feet away. The breaker box in the farm house is full, can an additional line & breaker box be mounted in the farm house for distribution?
2.) Given the description of intended outlets and lines, what size and how many different lines of electrical wire & gauges will be required to support the (A) 220V/50@ circuit, (B) 220V/30@ circuit (C) 110V/20 amp circuits?
3.) Due to old tin, slightly leaky roofing, all circuits will have GFCI breakers in the remote breaker box located in the dairy barn. The welding circuit outlet box will also be an outdoor style box with weather seal. Is it advisable to also install a local ground rod at the dairy barn? How many breakers do you advise?
Intended usage for the 20 amp breakers is typical shop use, I.e. Drills, 110V air compressors, power tools, etc.
4.) The new water well pump will be a 3/4 - 1 HP, four wire 220V/30 amp single phase. IT will have a seperate controller box mounted above ground. What is the depth that the electrical wiring required to be mounted below ground, even if run thru underground gray plastic EMT?
5.) Have I missed anything? Please advise.
FURTHER INFORMATION: EDITED POST

One of the posts asked what type of box/main breaker. There is only one main breaker/breaker box combo in the farm house. It is a Seimens Class CTL Enclosed Panel Board Issue B8725, Catalog number G2040MB1200, Series B Type 1 Enclosure. (H2190), The box says the factory installed main breaker can be either a Type EQ-948 or EQ-949. The Main breaker is located above all the breakers mounted with an up/down pull, unlike the remainder of the breakers (left / right pull). The main breaker is an Seimens ITE type, and does not have a visible amperage listed, but is a 4 handle (pinned together) type. The box info claims 200 amps MAX. {I told you this was an old house}.
The breakers are mounted double row, top to bottom. They are as follows:
MAIN BREAKER
120/240 V / @ ??? (200 max.???)
L1.)220v30 amp double pin R1.) 220v/30 Amp double pin
(Back bedroom, 220, not used) {Main Water Pump, 220}
above ex-washroom can pull, above will be used

L2.)220v30 amp double pin R2.) 220v/30 Amp double pin
(Utility/wash room, used) {Dairy barn only circuit, to be rewired}
above will be used above to replace, per the first posting.

L3.) 110v20 amp single pin R3.) 110V20 amp single pin
Kitchen, used Living room, used

L4.) 110v15 amp single pin R4.) 110v20 amp single pin
Kitchen lights & outlets, used {Bedroom , used}

L5.) 110V15 amp single pin R5.) 110v15 amp single pin
Bathroom, used Exterior lights, used

L6.) 220v30 amp double pin R6.) 110V15 amp single pin
Hot water heater, used Hallway lights, garage lights used

As listed above, I can only pull L1 and R2. L1 at one time was a circuit for the kitchen 220v oven and/or washing machine, now washing machine is in utility, circuit not used, gas stove in kitchen.
The ONLY circuit that ran to the dairy barn that I intend to re-wire, per the first post, is a 30 amp 220v circuit. That included the water pump and all lighting and outlets. That circuit appears to be only a #8 or #10 gauge 2-wire going to dairy barn. Revised estimates for total length from Main house breaker to where new breaker will be installed, will be 140 - 150 feet.
The air compressor referred to is a small 21 gallon, 110 v unit, 4.5 hp peak. The water pump will be a 3/4 - 1 HP unit, 220v30 amp. The outlets will be 8each, 20 amp 3 wire outlets, of which no more than one or two will be in use at one time (Shop use). The lights (4' fluorescent - 5 each). A single 220v50 amp plug outlet will be used for an AC/DC welding machine {SMAW/GTAW}, with a high frequency GTAW start box (110v). The welding machine will seldom be used.
QUESTIONS:
1.) IS the 3-#2 or 3-#3 wire (w/#6 ground) mentioned and advised necessary per code? Will 3-#4 (w/#6 ground) work for this application, with the revised footage? Strange, the old dairy barn went for 50 years with a single #8 or #10 feed. {Of course, it was two single incandesent light bulbs with 3 outlets}/
2.) I agree a seperate ground will be necessary. What size copper ground rod {I.e. diameter, length, etc.} with #6 ground wire attached.
3.) How do I three wire two switches located at opposite ends of building, to control the same lights?
4.) Will my main breaker box, as described, be able to handle the load, after pulling two 30 amp breakers not being used, and replacing with a 125 amp breaker?
PLEASE advise.FURTHER INFORMATION: EDITED POST

 

Wow, quite a mouthfull there. You will need Number 1 aluminum or number 2 copper for 100A service at that distance, bigger is better even. Your well can go on a 20 easily too if you like and its actual run draw will not be more than 6A at that voltage. I would even change air comp to 240 if you can, most can be changed and it just keeps from dimming stuff on starts. You need 4 wire feeding this building and a ground rod. You will probably need a main breaker panel as you will have a couple more circuits than allowed for a main lug panel. What power panel and what brand is in the house now. You will need 2 spaces to feed this and the max is a 125 I believe but a 100 is common and would probably be enough. Some panels accept tandem breakers to gain spaces.

 

Whenever you remove the existing circuits to the barn, you will gain space in your panel. I would run a 100 amp minimum feeder to the barn consisting of 3- #3 copper and 1- # 6 ground wire. in an 1-1/2" pvc (schedule 40 ENT) conduit.The wiring method underground whether you choose to go with direct burial (USE cable) will need to be buried a minimum of 18 in. to the top of the pipe or cable.The sub panel at the barn should have a separate ground bar installed.

 

Agree with everyone about the 100 amp service. You have two ways to run your wiring. 1. PVC (Electrical-gray) with individual conductors. 2. Direct burial cable.

The Conduit method will require more work as you must run and connect the conduit, fittings, etc. and pull individual conductors (together) into the conduit. For the DIY'er, this can create some problems if you aren't aware of certain things and don't know the little tips and tricks involved with pulling wires in conduit. This method of installation must be buried 18 inches below ground to the top of the conduit.

Direct burial cable in the 100amp 4-wire copper variety is extremely expensive and generally only available at an electrical supply house. My recommendation would be to buy a quadplex #2 AWG aluminum cable available at Lowe's. It is a twisted "cable" with 4 conductors and can be directly buried in the ground. It would need to be sleeved in PVC where it enters and exits the ground. It needs to be buried 24 inches.

Install a 100 amp breaker in your house panel. Install a 125 amp, main lug, 24 space, panel with a separate ground bar in the barn.

You could also contact the Power Company and see what it would cost to have a separate service installed. If you went that route, all you would have to do is install a meter base and 200 amp main breaker panel at the barn. If the power company would run underground power out, then you wouldn't even have to build a riser out of the meter base.

 

Number 4 wont do it. The 2 is aluminum or the 3 copper and those are minimums. You could go better if you wanted. That is for a 100 A breaker in the house. You need an 8 ft by 5/8ths galvanized ground rod. Your thing will probably handle the load fine as the only load you are really adding is the chance of welding. Home Depot carries quadraplex number 2 alum which would be economical and is rated for direct burial. Buy 10 more ft than you think you need, you cant splice it.

 

sberry,
The #2 alum.is only rated at 90 amps in the 75 degree C. column of table 310-16

 

Yes I know it is and I always use it on a 60 A breaker for garage feeds,, But are you not allowed to use up to the next size breaker when using it as a feeder? I am just asking also, not telling. I run into this before. For my money thats too much distance for that size wire anyway unless limiting it to 60. I would go up a size just for V drop when you started adding some load.

 

tex is right. Put it on a 90 amp breaker. It is good for 100 amps when used as a service feeder per Table 310-15(b)(6), but is only good for 90 amps when used to feed a subpanel. I wouldn't worry about voltage drop for a 100-130 foot run.

 

QUESTIONS:
1.) IS the 3-#2 or 3-#3 wire (w/#6 ground) mentioned and advised necessary per code? Will 3-#4 (w/#6 ground) work for this application, with the revised footage? Strange, the old dairy barn went for 50 years with a single #8 or #10 feed. {Of course, it was two single incandesent light bulbs with 3 outlets}/

>>>You could go back with a #6 or possibly #8 feeder if not for the 50 amp welder which I don't believe you had before. The #2 (aluminum) quadplex was suggested because of it's relative expense and ease of installation. You would need to purchase a 90 Amp Double Pole Siemens breaker which is possibly available at Lowe's or Home Depot and definitely at any supply house that sells Siemens (formerly I-T-E). The breaker style will be identical to the other double pole breakers in your panel. You will need to sleeve the cable into (1 1/2" PVC?) at both ends where it comes out of the ground.

2.) I agree a seperate ground will be necessary. What size copper ground rod {I.e. diameter, length, etc.} with #6 ground wire attached.

>>>Get an 8' long, 5/8" Diameter galvanized rod and a 5/8" ground rod clamp. Slide the clamp over the rod before driving because the head will "mushroom". Connect #6 solid bare ground wire to the clamp and the ground bar in your panel. All available at Home Depot.

3.) How do I three wire two switches located at opposite ends of building, to control the same lights?

>>>Run a piece of 12/3 with ground (if on a 20A circuit) or 14/3 with ground (on a 15 amp circuit) between the two switches and install 3-way switches. Cables will have black, red, white, bare conductors - total of 4). Refer to useful links for hookup of 3-way switches.

4.) Will my main breaker box, as described, be able to handle the load, after pulling two 30 amp breakers not being used, and replacing with a 125 amp breaker?

>>>Without doing a load calculation it doesn't look like you will have a problem adding a 90 amp (not 125) circuit since you don't cook or heat with electric. You will have a 90 amp circuit to the barn but that doesn't mean that your barn will be "using" 90 amps of your 200 amp service.

 

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426hemicuda
Member

Registered: Mar 2003
Location: Louisiana
Posts: 2
New Questions to Electrical re-wiring Dairy barn / water pump on Farm, Please re-read
Well, I settled for the more expensive copper feeder wire (actually not that bad at $1.35 foot). 3 wire #2 with solid #6 ground Romex, and 1-1/2" PVC. Strange, the Seimens dealer was out of 100 amp dual throw breakers, but did have 125 amp dual throw breaker for my main feeder box, which I bought. I did pick up a GE 125 amp contractors out door breaker box for the sub-breaker, with a 125 Amp main already wired with a 50@ & 30@ double throw, but 1" size. Also comes with 6each 20 amp, (of which I have pulled two, leaving 4). According to Uglys, the 3-#2 AWG romex is rated 115 amps, and the drop in voltage shows minimal at that distance. I did not find a galvanized ground, but did get a 5/8" 8 foot copper ground, and have a second 1/2" 8 foot ground which I will also attach to the 5/8 ground and mount 6 feet away, (dual ground recommended by dealer). Given the fact that the load at any time will never exceed at the 50@ outlet with welding machine (40% duty cycle) hardly ever running above 125 amps DC (less than half of its maximum 275 DC amps), three 4 foot 40w lights at any one time, and the 30@ for the water pump, which after starting will probably only pull 8-12@, this load should never exceed 85 amps. With using the #2 copper instead of the #2 aluminum, I should be able to avoid the expansion/contraction and loosening of connections. Should this work, with the 125@dual throw on the farm house main, and 125 main sub breaker with a 50@ double throw, 30@ double throw and 4 each 20@ single throw, of which no more than two 20 @ would ever be in use or even on ( different rooms, storage,etc.)?
2.) when connecting the #2 3-wire to the sub-main breaker, is it advisable to attach and crimp copper lugs to fit the sub-main breaker lug nuts, or to coil the "question-mark" style loop with just the copper wire. If crimping is insufficient, will attaching copper full circle lugs to the #2 wire via hard silver solder brazing suffice, or is that advisable?
3.) With the advice of the Seimens sales rep, they advised to use only Seimens breakers (although a GE dealer said thiers would fit). The Seimens dealer claimed that their buss bar was of different thickness and using another brand would or could create "hot spots" in the buss of the main panel, causing problems. Have you ever heard of this, or is that just a line of bull to sell a part? These breakers are the clip in style, not the bolt in.
4.) I did get the 2 wire #12 with ground wire for the 20@ breakers. I did get 50' 3 wire #10 with ground for the 30@ 220 feed to the water pump. After viewing the controller box, it appears I will definitely have to use full circle crimp-on connectors to bolt to the controller box for the water pump. The water pump depth is 88 feet. I will probably use about 35' of the 50' 3 wire #10 to reach the pump. Is that sufficient for size rating. The pump will be a 1 horse pump. The wire running from the controller box to the pump will be submersible 4 wire #10, with shrink tube covers on the pump. Any advise for the shrink tubing? Double up with two successive sizes? There will be a rope attached to lower the pump, so no load will be on the wires during install.
5.) I did get 3 wire #6 romex with ground wire for the welding machine outlet box (50@) which will be positioned no more than 8 feet from the sub-main breaker, running thru steel EMT conduit. (All wiring in the barn will be in steel conduit, with steel outlet boxes for all outlets and switches; rodent proof that way).
Do you see a problem with this?
Thank you for all of your responses, you have been a great help.


__________________
426

Last edited by 426hemicuda on 03-28-03 at 11:52 PM

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03-28-03 11:32 PM



texsparky
Moderator,Master Elec.

Registered: Sep 2002
Location: SPRING,TEXAS
Posts: 325
Whoa..... Back up !
Lets get the feeder right and then proceed with the rest of the wiring.

3 wire #2 with solid #6 ground Romex is not listed for ,and can't be used for underground (wet location use). #2 romex is only rated for 95 amps.

When we are discussing pvc with conduit,we are discussing individual conductors pulled through the conduit.(not type NM cable)

Secondly, # 2 Thwn is rated for 115 amps not the 125 Amp breaker that you bought.

P.S. it will help immensely if you would refrain from starting a new topic so that we can see what info. was given originally without jumping back and forth between posts. Just click on the post a reply at the bottom of the thread.

 

I did get 175' of the 1-1/2" PVC (Gray) to run the wire through to bury for underground. As I stated earlier, all of th3 3 wire #2 copper will be run in the PVC, from the Main Feed Box until about 10' after it comes up out of the ground at the Dairy barn's roof. From that point, I have a "pull - type" 1-1/2" 90 ell with cover, that I intend to switch to 1-1/2" steel EMT conduit to run through the barn's attic to the sub-panel box. I do have time after pulling the wire. I was intending to wire the barn with 3-12 for lights/outlets/3-#6 w/ground for 50@ weld outlet/3-#10 w/ground for 30@ water well outlet first, all thru 1/2" & 3/4" EMT Steel conduit FIRST, then do the final attachment to the main breaker LAST. Therefore, I do have time to switch/return the 125@ breaker for a 100@ Seimens, I will do so.
Now, with the 175' of 3 wire #2 copper romex with ground, running inside totally sealed PVC, with cemented joints, will underground burial be a problem, using that wire? It is bigger and more expensive than the #3 copper that was originally recommended. I may have used the term "Romex" incorrectly, but I think not. This cable has three, individually insulated #2 stranded copper wires, with a slight helical twist in the roll, with an insulated, solid #8 ground in the middle. All covered by heavy, black PVC into one cable. Description was "Wire NM-B-2/3-CU-WG-500R; E18679 Romex UL 600V"

 

Underground is considered a wet location,period. No matteer how well that you think you have sealed it, it will eventually fill up with water from condensation.

Take the wire back ! and get either type USE (underground service entrance ) cable or type thwn/thhn or some other individual conductors that are listed for underground use.

 

This is a rather large project for a guy that hasnt done it before. You need to break it down into phases so as not to get confused and confuse someone trying to help. All the branch circuits will take care of themselves and can be added in time but first things first. You are going to get too many things goin on at once and make expensive mistakes. Make getting the wire to the barn all one phase. Then panel install, then branch work.

 

What tex said is very important. Do not use NM cable in underground conduit!

 

426hemicuda
Check the rating of the individual conductor insulation in the NMB cable you bought. If it is THHN/THWN insulation then you can remove the outer jacket and the paper filler from around the equipment grounding conductor and pull the wires in as individual conductors that happen to be twisted around each other.

If the only grounding electrode is to be ground rods you will need two rods driven at least six feet apart. A single rod is only acceptable if you can measure it's impedance in the inspectors presence and demonstrate that it has an impedance to ground of twenty five ohms of less. It is a very rare single rod that measures that low so drive two.

Is the casing of the water well metal? If yes than you have an opportunity to provide a much better grounding electrode system for the entire farm by wiring the ground bar of the barn panel to the well casing. If you are not running a new circuit to the well then you probably won't want to do this but metal well casing is about the best electrode you can have if you are not served by a large network of underground metal water pipes.
--
Tom

 

I have read all that each of you have submitted. Thank You. Per last reply from Hornet, I DO have two 8' 5/8" Copper ground rods that will be installed 6 feet apart, using solid #6. No Hornet, The casing of the well is not steel all the way down. This is an old well, so I will have to use the two copper ground rods. I have yet to find out if the wires inside the NM cable are THHN/THWN insulation. I have yet to even uncoil it from the wood spool. I spent this weekend mounting the sub-panel into 50 year old concrete block (Hard block), and mounting the 50@ weld outlet, bending and running the 1/2" conduit with 110V outlets. I have multiple colored permanent marking pens, and I am color coding ALL of my wiring at the box and at the ends of connection, be they outlets, lights, etc. That way, I can avoid mistakes, particularily with the three way light switches. I am using a 20@ GFCI outlet for the first outlet on each 20@ outlet breaker, and connecting the load side to remaining 20@ breakers on each circuit (total of 3 per circuit, including 20@ GFCI outlet, on two circuits). I want to run two 4' double bulb 40W Fluorescent fixtures with two three way switches. I have been unable to find 20@ three way light switches, but I have found 15W three way light switches. I do have 15 amp breakers that came with the GE sub-panel. One could be used instead of one of the 20@ breakers for the lights in this one room.
Q1.) Would it be sufficient to run this light setup with the 15@ breaker for those two lights? It seems to be a minimal load.
As I stated earlier, all wiring in the barn for 110V will be 2-#12 AWG with enclosed ground wire.
Q2.) IF and only IF, the insulation on the individual wires inside the NM cable meets THHN/THWN, (is this possible???, or common???), would it be sufficient to strip the NM black outer insulation as hornet suggested, removing all paper and pulling individual wires? Is the ground wire, as it comes in the NM cable (#8 AWG, NOT #6), sufficient as an individually pulled ground, also?
There is also a correction on the air compressor. It is not a 4.5 peak HP, it is a 6.5 Peak HP. It claims to pull 15 amps on 220V. With that in consideration, will it affect my total load that much, if it is wired as a 220V on a 220V 20@ or 30@ breaker??
Q3.) TEX, since I do have time, I was able to find another breaker (100@ double throw) for the Seimens main house panel that feeds the sub-panel. The store I bought it at did not have a Seimens, but had a Murray brand, (never heard of them), but they claim that Seimens owns murray, and it should be equivalent. I would have preferred Seimens, due to what a Seimens factory rep told me concerning the fact that their buss bars are of different thicknesses than other MFGs., and using other than their breaker could create "hot spots" on the buss bar. Is this sensible, or just a BS sales attempt? I may just wait until the Seimens dealer gets more seimens 100@ breakers in next week, and return the Murray.
What I have learned so far, is that I now know where all of those dissappeared used car salesmen moved on to, after failing in used car sales, ....electrical supply houses.
Q4.) I also purchased a threaded sleeve nut with a ground attachment built in, for the 1-1/2" steel EMT tubing that will run through the dairy barn roof, to the sub-panel. Is it prudent to run a pig tail from it to the ground bar, to an unused ground screw on the ground bar side (right side) of the sub-panel ground buss?
Q5.) I noticed on the GE sub-panel contractors panel (Outdoor box style) that the top hole is much larger than 1-1/2", yet there is a plastic square cover with four screws. Is it common to drill that cover to 1-1/2" or 1-1/4", depending on what the incoming line tubing is? OR.... is there another "speciality part" that must connect in this oversized hole for a more firm attachment method?
SBerry, I appreciate your comments as well, but.... unlike you "sparky" guys, I would prefer to wire the barn WITHOUT any juice around to mess up my day. Then run the CORRECT wire thru the underground PVC from the barn (where I have room to uncoil) thru the PVC to the house, thru the attic (after coming up from under ground) and to the main box. I have yet to remove the main panel cover, but what I have seen from observing the input feed from Rural Electric is that it comes in at the roof from an overhead line. Strangely enough, you can not see any lines going down to below ground (House is on blocks). However, once you observe the main panel, there is one LARGE PVC coming up from below, and multiple #10 & #12 flat wires exiting the main panel above the panel. This appears to me that the main feed is coming in below the box to the top Main breaker. Whereas the individual output lines are exiting the top. Strange arrangement. What I have decided to do is finish the wiring of the barn, pull the CORRECT lines to the house in 1-1/2" PVC (Steel EMT in the barn roof due to rodents). get the lines to the box and call an electrician to inspect all work to that point and do the 100@ install in my main box. What is behind the hidden door (Main Panel cover) appears to be a total surprise, since the incoming and outgoing wires are directly opposite to how the wires feed to the house. Therefore, I may be looking at a shakey situation, and I would prefer someone more experienced to do the 100@ breaker swap supplying the sub-main. That may seem backwards to you, but the 110V / 220V new install seems much more do-able and safer for me.

 

They make a hub that fits that box for that. I am sure you are talking about a bond bsuhing on a connector but I am sort of lost here and not sure why you migh need it in this case. You can use 15 amp switches on a 20 A circuit, but 15 would be plenty adequate for the lights. You could add several more at that rate. The compressor isnt going to affect this much and you probably should but it on a 30 to avoid tripping on starts. What ever ground wire came with the cable is fine and if I could I would get the right breaker.

 

Are you going to have this project inspected?

Section 334.12 Uses Not Permitted.
(A) Types NM, NMC, and NMS.
(10)d. Where exposed or subjected to excessive moisture or dampness.

I've got news for you - PVC underground WILL be full of water.


What you need to do is pay an electrician to come out and go over your job and provide you with a plan and complete material list. You really need to come up with a legitimate plan BEFORE you start running out and buying your material. For instance, the supply house may not take back the #2 AWG romex because it has already been cut. This is one reason that many supply houses don't sell to DIY'ers - and only to professionals that take responsibility for what they buy. The majority of employees at supply houses are not licensed electricians and can't be held accountable for giving you the wrong product for your application. It is your responsibilty to choose the correct product for your need.

Regarding the Romex - you very well may need enough romex to get from your main panel, across your attic, and to a junction box on the outside of your house where you would switch to conduit and conductors rated for underground installation (THWN). There are other issues with running conduit that you must follow such as no more than 360 degrees of bends between pulling points.

When electricians run conduit on a job such as yours, they complete their entire conduit run first and THEN buy their wire. That way they will have an accurate measurement (count the number of sticks) and can purchase what is required. If you purchase your wire beforehand and then something unforseen in your planning causes your conduit run to be 15 feet more than you planned, and your wire which was to be 10 feet extra is now 5 feet short - well, the supply house isn't going to take it back so you will have to eat it.

It's very difficult to respond to all your needs when you ask so many questions. Your posts need to be streamlined into different areas of your installation. The only way to adequatley address all of your issues would be to take notes as your lengthy posts are read. Don't get me wrong, I'm willing to help you out but you got to make it a little easier on the readers.

 

Replies are in line.

Both the fifteen ampere circuit and the fifteen ampere switches would be fine. The code only requires the switches to be rated for the load to be switched rather than the entire ampacity of the circuit.

If the wire in the cable is THWN then you can strip it out of the cable and use it in the wet location of the underground conduit. The W in THWN stands for wet locations. THHN/THWN is the wire that is usually used in the construction of NMC cable. The ground wire is sized by the size of the breaker that protects the feeder. Number eight AWG is sufficient up to the 100 ampere breaker size you plan to use. I don't think the air compressor will effect total load but you will want to tell us the information on the motor name plate rather than the information from the manufacturers directions so we can help you figure out the size of the circuit and breaker to supply it. motor branch circuit calculations are more complex than some.

You do need a seimans breaker unless the Murray breaker is listed or classified for use in a seimans panel. If it is listed for seimans it will be marked on the breaker case. If it is classified for seimans than there would have been an insert in the packaging that bears a laboratory listing mark and says what panels it is classified for use in.

When you say through the roof do you mean through the ceiling into the attic or actually through the roof to the outside of the structure? Bonding the feeder raceway to the panel's Equipment Grounding Conductor (EGC) bus bar will do no harm but it is not necessary unless the panel cabinet is non conductive or the raceway comes in through concentric knock outs. If the panel cabinet is metallic and you buy the bolt on threaded hub that is sized for the raceway connector you are using then you will have no problem with the continuity of the raceway.

Were you make the transition from the underground PVC conduit to the Electro Metallic Tubing (EMT) inside the barn you will want to bond the EGC to the EMT. You can do that by connecting a short piece of the number eight copper to a bonding bushing installed on the EMT connectors threads and connect it to the EGC with a properly sized split bolt connector. If the box were you make the change is metallic rather than plastic you could run the bonding jumper to a lug installed in the box.

You must buy the 1&1/2" threaded hub for that opening to use for threading the EMT connector into. You buy it from the same place you bough the panel.

I think you are on the right track with the hook up by using an electrician to do the panel work. If the meter enclosure is on the outside wall and the panel is on the same wall inside then chances are pretty good that the supply conductors come in through the back of the panel via a nipple from the meter enclosure.
--

 

I take it there must be a reason you need to go thru the attic? Remember when designing not to get locked ito preconceived ideas, thats why we often ask for advice too,, just to get a different way of viewing a project such as locations and such. There have been lots of times I have gotten improvements from friends such as," why dont you just do this?" You can enter the sub from the bottom or side, it doesnt have to come from the top maybe,, or run the pipe along the wall a few feet, or move the panel location a bit to make it better. I dont think rodents will chew thru that big pipe if it was plastic. Thats why I read these posts, to get ideas from other guys doing the same projects. About half the time the answers come without having to ask.

 

Gentlemen, Thank you for all of your responses. I really appreciate them. I just finished talking to the tech at the electrical supply house and Hornet is correct. He has assured me that the internal wiring within the romex is THHN grade. Tex is also correct, they will not take back what has been cut. Therefore, It looks Like I will have to start stripping the outer jacket NM romex insulation. Now would someone please answer just a few brief questions for my personal reference in the future.
1.) IF Romex NM 3 wire #2 is only rated at 95 amps, and is illegal for underground, then tell me why, after stripping the outer protective jacket and pulling the THHN conductors contained within as seperate wires, that it is legal for underground AND it also gets an amperage increase as THHN vs romex, according to UGLYS, from 95 to 130 amps?
Is it because of the paper insulation around the ground? Is it because of the extreme close proximity of the wire when twisted into cabling?
2.) If Romex is being run underneath a house on blocks, is it required to be buried will attaching to the house frame beams suffice? (was considering the SBerry method of entering the main box from below).

 

THHN is not quite good enough. You must also ensure that it is also rated THWN. Although almost all individual strand THHN wire sold today is also THWN, I'm not sure that that is true for the wires within Romex cable.

Romex is more temperature limited than the individual strands within it because the packaging encapsulates heat.

 

The type of wire in the cable is usually marked on the cable jacket. Look at the jacket under a strong lite and you should see the markings.
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Tom

 

As I stated earlier, you can't depend on the supply house salesman or the final word on the code. I think he was right in that the conductors are THHN - but I don't think they are THWN. They are rated 90 degree C in dry locations. They cannot be used in wet or damp locations. If I was going to install romex underground I would leave the outer jacket on - at least it is moisture resistant. Of course, I wouldn't install romex underground. I would use THWN in conduit or a direct burial cable.

I'm assuming you aren't planning on having your project inspected. If not, you can strip the romex and install it underground. It will probably last several years and do fine, but may fail eventually. If you are planning on having the job inspected, by all means call the inspector and ask him if you can use the romex in such a fashion. You wouldn't want to go to all the trouble of stripping and pulling the wire in only to have it fail inspection.

 

OK, let me throw my 2 cents in here.

First #2 romex is only good for 95 amps. #2 THHN is not good for 130 amps, only 115. 130 amps is the rating at 90 degrees C (for derating), and since no device I'm aware of allows for 90 degree terminations, you can only go with the 75 degree column. However, for the romex, you may use a 100 amp breaker because by code, if the amp rating you have is no a standard breaker size, you may go up to the next standard. 95 is not a standard, 100 is.

Is NM-B made from THHN???? Maybe. I've just looked at some NM-B (AKA romex) and the problem is that the individual conductors do not apear to be labeled, nor is it mentioned on the outer jacket. So while is maybe THHN you can not prove it (nor can you prove it may be THWN). At least with the wire I have this is true.

I'm not sure why Romex is rated lower than THHN. I read what John said, but I'm not sure I buy it. I don't buy it because I can derate romex from the 90 degree column, so if I bundle three 12/2's together, I still get 21 amps after derating the same as if I ran 6 pieces of THHN in a small conduit.

I agree with mcjunk.. if you are going to get this inspected, call first. If not the inspector will most likely fail this job every which way.

If its not going to be inspected, leave the cabel bundled (easier to pull and more protection) and go with a 100 amp breaker max. I don't remeber all you need to run, but my house runs off a 100 amp breaker and has a well, septic pump, water heater, AC, etc all on electric.

 

I just guessed at why Romex (aka NM) is more restricted in ampacity than THHN. But it is no guess that it is indeed more restricted. Article 334 in the 2002 NEC covers NM cable. Article 334.80 specifically limits the ampacity of NM to no more than the 60 degree column, although it does allow it to be derated from the 90 degree column. No such restriction exists for THHN.

 

John, I agree. Your guess on the Romex restriction is better than mine which is simple the code people hate romex (of course MC/AC falls under the same restriction).

They do probably feel that the cabeling has some negative property, i just don't see it.

 

Even if the NM cable contained dual rated THHN/THWN conductors, what do you suppose the odds of stripping 175' of it without nicking the insulation are? One small nick is all it takes.

 

OK, thanks to all of your input, I have re-thought this so that I will not (I hope) have to eat all of this 175' of purchased NM-B cable. I may be able to use 50% of the NM-B if the following is legitimate. I can save the rest for future shop expansions for inside wiring.
I retreived the info on the NM-B (exact wire that I have), the THHN/THWN and the USE-2 wire at http://www.essexgroup.com/electrical/elec_building.htm
The wire that I have is NM-B UL Listed number E10816. According to the information (which matches the number on the wire), the wire insulation covering on each individual strand meets or exceeds THHN, but there is no mention of THWN (you are correct Tex and John, even though the insulation thickness and jacket thickness detailed for both THHN and THWN are the same and PVC comprised, but possibly different chemical make-up). In order to utilize at least 50% of the NM-B wire already purchased, please consider this. This scenario from information gleaned from SBerry and Tex and Marco.
Q1.) IF I used the NM-B cable (in stripped fashion, using the single strands {thhn} without outer NM-B insulation, used to run thru PVC in both the house attic and dairy barn attic from each box {Main and sub-main} and down the outer wall of both the dairy barn and house (in PVC) to a outside terminal junction box mounted on both the dairy barn and house. At that point, I could join USE (Found USE-2/RHH/RHW-2 in #2 on same www.essexgroup.com website) to go into underground PVC extending from dairy barn junction box, going underground to exit above ground in PVC to the junction box mounted on the house, I would only need approximately 110' of USE #2 AWG wire, which has a high 90°C rating both wet & dry according to essex. Using this configuration, I would only have two 90° turns in each sub-assemblied installation, both the dairy barn, the underground installation in gray PVC, (easier to pull), and the house.
***In essence, it would be approximately 35-40 feet of stripped outer jacket NM-B (individual THHN) from the main breaker box run in PVC from the attic,
***connected at a house outside junction box where 3 individual USE-2 #2 AWG, plus #8 AWG bare ground would be run 110' from the first junction box underground, connecting from below to the outside junction box mounted on the outer dairy barn wall,
***at that point, it would be joined to stripped outer jacket NM-B (individual THHN wires) from the dairy barn outside junction box, running approximately 35-40 feet, through the dairy barn attic, down to the sub-main breaker box inside the dairy barn.
Q2.) Do you see a code violation with this scenario??? This would allow me to utilize some of the purchased wire, without letting it go to waste.
Q3.) Would utilizing this method not give me 115 amp vs. the 95 amp rating that the encapsulated NM-B (which retains heat) would have given, had I used the NM-B throughout, in its original form?
Q4.) Does this look much more reasonable and code compliant?

 

The ampacity of the conductors is limited to the 75°C value by the listing of the termination's. The circuit breaker and the barn panels main lugs or circuit breaker as well as the devices used for splicing will only be listed for 75°C. The ninety degree value is only used as the starting point for derating the conductor for higher ambient temperature or more than three current carrying conductors in the same raceway or cable.

Your installation is more likely to be trouble free if you avoid the splices all together by buying THWN conductors that will reach the whole way. Strip the first four feet of the cables jacket and look for the conductor markings. See if it is marked as THHN/THWN. If not then check with the supply house were you bought the NMB cable in the first place and see if they will give you credit toward the purchase of the needed THWN minus the restocking charge for having to handle the cut wire. It will not hurt to ask.

It will probably be a lot cheaper to buy THWN to run through the raceway that will be underground rather than to use type SE conductors. Type SE conductors are only needed for direct burial. Since SE is normally only stocked in aluminum you would have to go up to size 1 AWG to have an ampacity of 100 amperes. The price difference between the two types of wire may be substantial.

Since you are not practiced at insulating split bolt connectors I suggest you use splicing blocks that come with an insulating cover to use in making the connections in the boxes.
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Tom

 

Using your method of installing your circuit with two junction boxes, I would suggest the following:

1. Do not strip the romex, except where it enters the panel and the junction boxes. On the house end, use an LB and a conduit stub to get the wire into the attic and then run the cable to your main panel without conduit. On the barn end, run your PVC conduit and pull the romex unstripped through the conduit to your subpanel - only because you are worried about rodents. The #2 romex is good for 95 amps and can be put on a 100 amp breaker which should be plenty adequate for your situation.

2. For your underground, the USE conductors are rated for direct burial. I would only sleeve conduit from where they exit the ground to the junction boxes. If you do want to use conduit the entire way, I would go with 2" conduit - it's not much more expensive and would be an easier pull for a DIY'er. You will need #1 USE aluminum if you want to use the 100A breaker - #2 USE aluminum will require a 90 amp breaker. Direct burial cables need to be buried 24" but you only need to go 18" (to the top of the conduit) if using PVC.

3. Your split bolts will need to be rated for splicing aluminum to copper. You might should just pull your wires and let the electrician who is going make your final hookup in your main panel make those splices as well.

4. Go ahead and finish this part of your installation. You can safely work in your subpanel by "locking off" the 100 amp breaker in your main panel.

 

This would not be code compliant. The required building disconnecting means must be located at or very close to where the supply conductors enter the building. Code states " inside or outside, nearest the point of entrance". The allowed distance the conductors may travel indoors is a call only your local inspector may make, as only they can define nearest, but rarely is it more than 6-10 feet.

Use a 2 pole 100. Forget about the 125, at that distance 125 amps will drop the voltage to undesirable levels. You would also have to make sure that the individual breaker bus slots in your (house)main panel are rated for 125 amp, they are often limited to 100.

 

Bolted Fault makes an excellent point. Instead of making the change from one conductor type to the other in a junction box you should make it in an enclosed breaker cabinet or a switch enclosure. In that way you will have a building disconnecting means on the outside of the barn. That will need to be a weather proof enclosure unless you use an LB condulet on the outside and connect it through the back of the switch enclosure on the inside. Since you already said that the barn leaks and you are using a weatherproof panel for that very reason I would suggest the use of a weatherproof switch on the outside of the building. You can bring the underground conduit up into the bottom of the switch enclosure and take the interior raceway out of the back of the enclosure. The switch or breaker assembly that you use must be "suitable for use as service equipment." The enclosure will have a neutral block in it but you will need to add a grounding block or multi barreled lug. You will then make the connections to the grounding electrode conductor on that grounding block or lug. Any bonding screw or strap that connects the neutral block to the cabinet must be removed.
--
Tom

 

***Comment to answer some critical early questions***:
I contacted the tech support group at Essex Building Wire division's main factory today. After explaining my situation, followed by some persistent questioning, I was informed by the head of their quality control that Hornetd is indeed correct. The Essex QC did check and verify that the internal wires within their NM-B did indeed meet THHN and faxed me data to this effect. I then informed him that I had viewed his data for THHN/THWN wire and noticed that the PVC insulation and nylon jacket was identical in thickness. I inquired IF the individual #2 AWG wires within the NM-B jacket was equivalent or exceeded THHN as the data claimed, did it not also meet THWN? He checked and informed me that first, the insulation coatings they use for the NM-B inner wires are THHN and is identical to the coatings used on THWN, for their wire. Same insulation, same thickness, no difference. I inquired as to why they did not advertise it as dual THHN/THWN? He informed me that since it was packaged as NM-B, 1.) they only have to put the package classification on the "OUTER" insulation, when in this case, it is shown as 3-#2 THHN on the NM-B. 2.) He did say however, they do not state it also meets THWN, since NM-B is not rated for outdoor use, to list THWN would cause some problems with NEC, an it may be used improperly, by someone mis-interpreting the proper useage of NM-B.
I did inquire that if the outer NM-B insulation jacket were stripped (without nicking the inners), would it be an equivilent to THHN/THWN in individual conductor form? He did reply yes, as stated earlier, it is the exact same insulation as is on their THHN/THWN (they don't have two seperate insulation formulas for the two different THHN/THWN wires that they manufacture), except that it would not be marked THHN/THWN, since the inner wires are not required to be marked so, for NM-B.
Thanks HornetD, I breathe much better now that I have assured myself that the warnings given earlier are met as far as THWN safety concerns go. Now, with this in mind, I do have some possibilities.
Per the last two comments on the forum, I did not think of the outer breaker box for the building, so.... I noticed at Home Depot that they have a small, outdoor 100amp breaker/disconnect box for $19, that may be perfect for the overlooked outside breaker/disconnect item required on the dairy barn.

Q.1) IF I leave the NM-B insulation on from the House Main Breaker to just before the point of exit from the house, at that point strip the outer jacket NM-B black insulation and pull it thru the PVC, down the wall of the house, thru the underground PVC and back up to the dairy barn wall as 3 single, stranded #2 THHN/THWN, w/#8 solid bare copper ground. It appears (this is only an assumption) I would have technically met the intent of code restrictions. Am I correct? BTW Tex, this is a retrofit of old wiring and most probably will not be inspected, but I still want it safe, proper and compliant with the intent of the code.

Q2.) IF I then use the small, 100@ outdoor breaker/disconnect box (w/100 amp breaker) and mount it on the outer wall of the dairy barn about 4'-5' off the ground, enter the box from below, and exit thru the top with a waterproof 1-1/2' top plate with gray PVC to the attic, (Switching from PVC to EMT using female threaded end PVC fitting to a male EMT compression fitting), then running NM-B from the top of the outer dairy barn breaker/disconnect box to the Sub-Main breaker. (Opps, Forgot, strip the NM-B outer jacket until it is indoors under roof in the dairy barn attic, within the EMT). Would this meet the intent of the code, and technically be compliant? I would then have an outdoor breaker box, meeting what one of the later comments/advisors suggested.

Q3.) I noticed within the small, outdoor 100 amp breaker/disconnect box that there were attachments for mounting the 100 amp 220v breaker hots and a seperate neutral buss, however, there did not appear to be a ground buss as seen in my sub-main panel (even though the neutral and ground buss are connected, but have different sides for attachments, I assume it is standard for neutral on left, ground on right). Here is where I need the advice. IF I do use this small, outdoor disconnect breaker box on the dairy barn, attaching the breaker hots and neutral are a given. When it comes to attaching the ground wire, would it be prudent to utilize a end to end connector rated for #2 to #8 AWG (up to 105°C rating) with supplied shrink wrap to connect the ground wires and allow it to pass through or..., attach it with an additional pigtail wire to also ground the sheetmetal disconnect/breaker box too?

Q4.) I assume the comment from BOLTED FAULT about an outside breaker box would only apply to having one mounted on the dairy barn at the point of entry of the current to the barn, and not having one also mounted on the house, since the house main is supplying the current. Is this correct?

Q5.) This is only a thought, but... I did realize that the ground wire within the NM-B is bare, after stripping the outer jacket it will be totally exposed. I have reservations about using a bare ground within the outdoor breaker/disconnect box. Whats more, I am questioning if it is even legal or legitimate for a ground running thru underground PVC? Is it legitimate? Should I run an insulated Ground throughout? Is there a code compliant issue here?

Q6.)I did purchase AWG #6 stranded and insulated for running to my twin ground rods from my sub-main breaker box, seperated 8' apart. Is it compliant to strip away about 2" of insulation on the first ground rod without cutting the ground wire, attach it where stripped, and then run the wire to end and attach the end (stripped) to the second ground rod? There would be no cuts/breaks in the wire at the copper ground rods. Is this a typical practice?

 

In my opinion you would be walking on a slippery slope with your assertion that the stripped romex is rated for wet locations - IF you were going to have your job inspected which apparently you are not. I have no doubt that your project is supposed to be inspected - it is much, much more than a "retrofit of old wiring" as you have apparently assured yourself. IF an inspector was involved, he wouldn't want to hear about your conversation with the supply house or with Essex - he would want to see TH(W)N stamped on the wire or would want to see a technical specification sheet from Essex that does indeed state that the wire is rated THWN. If it is indeed built to the specifications of THWN (which I'm not discounting) but isn't labeled as such, then a picky inspector (those that inspect DIY'er projects always are) would turn the job down. Don't get me wrong, your installation (according to a phone conversation with Essex) would be safe and sound if done correctly but would not pass inspection by an inspector going by the letter of the law. Essex does sell a product with THWN and UL stamped on it that is made for your application.

Ironically, the only conductor that you probably wouldn't have a problem from the inspector with is the bare grounding conductor.

You can throw all my "criticism" out the window if you aren't going to have your job inspected and feel self assured that what you are going to do is safe and correct. You came here looking for advice from people with experience in the trade and you can take it or leave it; it doesn't really matter to me.

 

Sirs, I wish to thank all advisors with my deepest appreciation. I do agree that I should get this project inspected. I am a bit leary about having the inspector view the existing Main Breaker box, that was wired years ago (not by me!!!), for fear that it would maybe appear; as a total code travesty, when all other wiring would, or could possibly meet code. I do intend to purchase the THWN wire for the underground install. I will save all remaining NM-B wire that is not used for future installations indoors for a future shop expansion. Thanks again for all of your answers to my questions.

 

Replies are in line.
An inspector might give you a hard time about the markings on the wire but I think that the path your taking is fine.

Were your NMB first enters the PVC conduit from the house attic you will need a female adapter and an 1&1/2" cable connector. I suggest you make the switch to EMT at the breaker enclosure that serves as your building disconnecting means. This will bond the EMT to the equipment grounding conductor at that point and lower the impedance of the fault current path.

Do Not attach the neutral in that building disconnect enclosure. If you can run it right through the enclosure without any break or splice. If you can't manage that then splice it to make it continuous but leave it insulated from the enclosure. Use the buss bar that is supplied with the enclosure to terminate the bare #8 Equipment Grounding Conductor (EGC). That buss bar is also were you will terminate the #6 stranded Grounding Electrode Conductor (GEC) that will run to your grounding electrodes (ground rods). Drive the rods through the bottom of the trench and connect them to the GEC before you back fill the trench. If you strike rock bottom before the rods are fully in the code permits you to bury the rods in the bottom of the trench laid flat. Remember to keep the rods not less than six feet apart. keeping them further apart would be better.

That is correct. The only reason that you would have a box at that end is ease of pulling the wire. If it is feasible to pull the wire directly through the end of the PVC conduit into the attic then you don't even need a pull box on the outside of the house. If you do install a pull box it will need to be quite large. The code requires that pull boxes for straight pulls be eight times the trade size of the raceway. That means that the box should be a 12" X 12" X 4" weather proof box. If your supply house can provide you with a straight condulet for that PVC conduit that may be less expensive and will also be less visible on the wall of the house.

It is perfectly acceptable to use a bare EGC in the conduit. You can even run a bare copper EGC in a trench for direct burial unless there will be livestock present or the soil is uniquely corrosive to copper.

The method you have outlined for attaching the GEC to the rods is how it is usually done. I would suggest that you install the rods at the barns building disconnecting means rather than at the barns lighting and appliance panel. Since part of the reason that you are providing a grounding electrode system for the barn in the first place is to provide some lightning protection for the wiring you want to make the grounding connection to the EGC at the point were it enters the building. From the building disconnect on the conductors will be shielded from some of the induction effects of lightning by the steel of the EMT and the metal cabinets of the panel and the building disconnect.

I have one last suggestion but let me first say that there is no rule or even generally accepted practice that requires that you follow it. Since the only grounding electrodes on the premise are driven rods and the impedance of driven rod electrodes is often quite high you may want to consider bonding the house grounding rods to the barn grounding rods by running a bare number two copper conductor in the bottom of the trench OUTSIDE of the PVC conduit. The bare number two AWG copper would be run from the barn's building disconnect, through the trench, under the house or through the attic (under being better), to the GEC of the houses service equipment. This would convert all of your round rods into a large grounding electrode system and improve the grounding of the entire premise. You would make the connection to the existing GEC with a split bolt connector. Although the bare number two AWG in the trench is not a ground ring because it does not circle the building it will behave as one electrically. The additional contact area of the bare number two will markedly reduce the impedance of the premise grounding electrode system.
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Tom

 

I have the Outside rated, 100 amp disconnect box ready for installation. I have been reading other advice columns in this electrical group. Most of you who reply, are aware of my continuing situation. It has been expensive, but I have got the correct wire needed now. My question pertains to the wiring of the outside service disconnect on the dairy barn, prior to it going in to the sub-panel for lights, outlets, water well pump, air compressor. HornetD suggested the following:
QUOTE:
{Do Not attach the neutral in that building disconnect enclosure. If you can run it right through the enclosure without any break or splice. If you can't manage that then splice it to make it continuous but leave it insulated from the enclosure. Use the buss bar that is supplied with the enclosure to terminate the bare #8 Equipment Grounding Conductor (EGC). That buss bar is also were you will terminate the #6 stranded Grounding Electrode Conductor (GEC) that will run to your grounding electrodes (ground rods). Drive the rods through the bottom of the trench and connect them to the GEC before you back fill the trench.} ENQUOTE

Per what I have also read, others have advised buying an auxiliary Grounding block for about $5.00 and installing it in the outside disconnect for the Dairy Barn. I have a GE 100 amp, small, outside service disconnect It appears that there is only room for three wires to attach, the insulated two main hots bars, and the seperately insulated neutral buss bar. There are no ground bar connections. As stated earlier, I do have a few end to end splice connectors rated from #2 to #8 AWG with shrink wrap. I do have a heat gun, for the shrink wrap. Is it required by Code to buy an auxilary grounding block to connect my #6 ground wire going to my ground rods, a box ground pig tail attached directly to the box, and #8 coming from underground PVC, and #8 going to my sub-panel? If I do it that way, I know to remove the green screw and check ohms to ensure that it is not grounding at the neutral.
OR.....should I heed the advice above, splice the #8 Neutral and thoroughly insulate it with multiple shrink wraps and allow it to pass thru the box without buss connection; then use the neutral buss as a ground buss for my ground rods (without removing the green screw), attach all ground wires including grounding of the exterior box (with green screw)? Is that also code compliant? I am not second guessing anyone, I just want to make sure I am legitimate.
QUESTION #2: I also have a question regarding the attachment of #2 wires to the buss bars, (regardless of hot/neutral, etc.). Is it compiant by Code, to use Copper, Crimp style, full encirclement type lug ends to attach to the fixed bolts with nuts on the buss bars (similar to those crimp-type copper lug ends, used to connect larger sized wire for welding machine leads), or must you use stripped wire ends formed into loops?
I do realize that the two hot wires leaving the Dairy barn outside service disconnect will be coming from the two wire connections from the breaker, the above question is pertaining to the incoming wires from the main panel via underground PVC, which will bolt to the buss bars. The above question should also apply to incoming ground and neutral.
Please respond. Thank you everyone for all of your comments and advice.

 

If it makes you more comfortable then buy the auxiliary grounding block and use it as it will certainly be easier to use.

Is your enclosed breaker assembly not equipped with lugs for terminating the #2 AWG wires? What brand and model number is it? There should be lugs (i.e. pressure terminals with set screws) to use in connecting the supply conductors. If the buss bar only has threaded studs then you buy the correct lugs at the supply house were you bought the breaker enclosure. These will have a hole in them that slides on to the threaded studs after which you tighten the bell nut that came on each stud down onto the lug to connect it to the buss bar. You then place the stripped supply conductor into the lug and tighten the allen headed set screw. Theoretically that is supposed to be done with a torque wrench set to the inch pounds marked on the enclosure label and on the lugs.
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Tom