Review of Plan Requested

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  #1  
Old 04-01-04, 07:38 AM
msulliv3
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Review of Plan Requested

First, thanks to all who offer advice....spent much time reading here and thinking (hoping I am ready to tackle my project: Wiring a pole barn....150' from house, want lights and compressor (30A). Plan as follows:

1) 60A double pole breaker from house box (from current electric dryer space...going gas). Question: Do I need a second box inside, or can I go straight from the main panel breaker to the barn as long as I protect the wire from the main panel to the trench??

2) Taking the 2 hots, and 1 neutral wired to the main panel neutral bar. Schedule 80PVC where exposed.

3) 6/2 AWG UF buried 24 inches. Same trench as 1" PVC water line buried at 36 inches.

4) 60A service panel with disconnect in the barn.

5) 2 - 8' ground rods into my sandy loam soil, 6 feet apart connected to common neutral/ground bar of barn panel.

6) 30A double pole for the compressor circuit.

7) 15A circuits for recepticles/fluorescent lights....max 5 per circuit. Question: How many 4', 2 tube lights are recommended for a 36x48 barn to give sufficient shop light??

8) Inspection

Thanks in advance!
 
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Old 04-01-04, 07:44 AM
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1) No second box required. I'm not even sure what this second box might be.

3) 6/2 UF provides two hots and a ground, not two hots and a neutral. You can't use the bare wire in 6/2 as a neutral.

5) Perhaps not required (although perhaps it is required), but separated neutral and ground is better.

Use 6/3.
 
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Old 04-01-04, 10:01 AM
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You state that the installalation will be subjected to an inspection. Please take note of this relevant Code-Article which permitts bonding the Grounded (Neutral) Feeder conductor to the Grounding Electrode at the "detached" structure.

Art 250.32, (B), (2), Grounded Conductor------ "(When) an Equiptment Grounding Conductor is NOT run (to the (detached) structure), and THERE ARE NO continuous METALLIC paths ( water-pipes) bonded to the Grounding system in both buildings, the (Neutral Feeder Conductor) shall be connected to the Grounding Electrode and shall be used for Grounding and bonding---"

The purpose of this Article is to avoid a Neutral current being conducted thru metallic pipes between the two stuctures


Good Luck & Enjoy the Experience!!!!!!!!!!
 
  #4  
Old 04-02-04, 05:41 AM
msulliv3
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Thanks for the responses.

Just to confirm I got it right:

Will use 6/3, with Black and Red as hot, White as neutral. Ground wire is not used.

The neutral and ground bars are tied as one in the box in the barn. The ground wire from the ground rods connects to this combined neutral/ground. Wiring to recepticles/lights is just black and white, no ground wire needed.....ground accomplished via ground to neutral.

Thanks again!
 
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Old 04-02-04, 07:37 AM
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You have two options for a detached building subpanel:[list=1][*]If there are no metallic paths between the buildings (no water pipe, no gas line, no TV cable, no phone line, no air ducts, no nothing), you are allowed to bond the neutral and grounding at the subpanel, and to share the same wire for neutral and grounding.[*]Otherwise, you must keep the neutral and grounding separate at the subpanel, and run separate neutral and grounding wires from the main.[/list=1]Even if #1 is allowed, we always recommend #2 anyway.

You seem to be heading for #1, but since you have this unused grounding wire anyway, I encourage you to use #2. It's just about the same cost and effort.

In either event, however, you still absolutely need a grounding connection to your receptacles and switches. Just because grounding and neutral are bonded at the subpanel does not mean that you can share them at the outlet. This is a very common and very dangerous misconception.

I am a bit worried. You sound like you are inventing your own electrical rules as you go along. That's not a great idea. Study up. Read some books.
 
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Old 04-02-04, 07:58 AM
msulliv3
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Thank, John. Appreciate the detailed feedback. Sad part is I have read too much it seems....

Guess I was leaning towards #2 because I thought I understood how to make the physical connections. Whereas I understand the function of #1 more intuitively. But think I am getting there:

Using the seperated ground at the subpanel approach would go as follows with 6/3?

1) From the house main panel: Black and red as hots off double pole breaker, white from neutral bar, ground from ground bar.

2) In the subpanel in the barn: White to neutral bar, ground to ground bar. 2 ground rods to ground bar.

3) For lights/recepticles: black nd white from 15A breakers, ground tied to panel ground bar.

4) For Air Compressor: Double pole hots with neutral from neutral bar. Question: How do I tie this to the ground.....plug is only 3 prong??

5) Inspection.
 
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Old 04-02-04, 08:32 AM
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Question # 7

36' X 48' = 1728 SF @1.5 watts SF = 2592 watts of lighting

divided by 80 watt (4 ft w/ 2 tube fixture) = 32 fixtures.

Seems like a lot of light. You may want to consider increased light levels above work areas and lower levels in storage areas.

Also noted you mentioned 15 amp breakers for receptacles. If you are going to be using power tools on these circuits I would use a 20 amp circuit and # 12 wire. (You can use #12 wire with a 15 or 20 amp breaker but you definitely CANNOT use #14 wire on a 20 amp breaker).

DavidJ
 
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Old 04-02-04, 08:49 AM
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3) White wires do not attach to breakers on 120-volt circuits. David's suggestion to use 12-gauge and 20-amp circuits for receptacle circuits is a good one. Make sure all the receptacles are GFCI protected.

4) The compressor does not use a neutral, just two hots and a ground. 10/2 will do.

You got your permit yet?
 
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Old 04-02-04, 09:15 AM
msulliv3
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Thanks again.

No, waiting on permit to see if I felt comfortable doing it, else would hire it out and let the electrician/contractor pull it (best from what I've read for accountability).

In my area, they also give a homeowners permit.....but no advance plan review required. Pay the $50 and call when done for final inspection since no drywall. Only 1 inspector for a pretty large developing area (1/3 of a county) who is never available to sit down and review in advance.


Summary of the plan....Going to give it a try, thanks to all the help and info here!


1) Add 60A double pole breaker to house main panel (previous 30A for dryer...going gas). Wire direct from breaker to barn panel.....

2) Using 6/3 AWG UF: From the house main panel: Black and red as hots off double pole breaker, white from neutral bar, ground from ground bar.

3) Schedule 80PVC where exposed to 24 inch deep trench. Same trench as 1" PVC water line buried at 36 inches.

4) 60A service panel with disconnect inside the barn. White to neutral bar, ground to ground bar. Do not bond neutral and ground bars.

5) 2 - 8' ground rods, minimum 6 feet apart connected to ground bar of barn panel.

6) 30A double pole for the compressor circuit. 2 hots and neutral to compressor recepticle using 10/2. GFCI??

7) 20A circuits for recepticles/fluorescent lights....max 5 per circuit using 12/2. GFCI on each circuit.

8) A whole lot less than 32 light sets! Thanks, David, will definately take your suggestion and reduce storage area light.

9) Inspection.
 
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Old 04-02-04, 09:48 AM
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No GFCI required on the 240-volt compressor circuit.

Sounds good.

Do an electrical continuity test with your ohmmeter to make sure that your neutral bar and grounding bar are indeed isolated. you'll have to do this test before you connect any wires to them.
 
  #11  
Old 04-02-04, 01:34 PM
shreveporteric
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Just curious-- will the feed wire from the house to the barn be buried? I read over the responses rather quickly and might have missed something, but if it is buried shoudn't the wire be THHN/THWN instead of AWG? I thought the presumption was that wire even in conduit wiill eventually be exposed to moisture and water. Just curious and intrigued by all this.
 
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Old 04-02-04, 01:58 PM
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AWG isn't a wire type. It's a wire size.

msulliv3 is going to bury 6/3 UF-B 24 inches deep. He doesn't plans any conduit after the cable reaches the bottom the trench. UF-B is approved for direct burial.
 
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Old 04-07-04, 11:48 AM
msulliv3
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Based on my measured distance of 225 feet, vs 150 feet estimated (bad eyes, I guess), I plan to go with 4/3 with ground. However, can't seem to find it, except at specialty places via special order....cost shocked me (no pun intended)...about $2300 per 1000 feet for UF.

Looking at going with conduit and pulling it. Questions:

1) Can I use plain THHN 4....3 wires (hot/hot/nuetral) and ground??

2) Will go with at least 1.5" PVC even though can apparently go smaller...want to ensure it pulls through. Any problems here??

3) Does the conduit have to be schedule 40, or can regular water line PVC be used??

4) Does schedule 80 PVC that I will use above grade bond to Schedule 40 and white PVC??

5) Is #8 for ground sufficient for this set-up?

Thanks in advance!
 
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Old 04-07-04, 12:17 PM
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1) "Plain" THHN, no. You need THHN that is dual rated THWN. Most is.
2) No.
3) You must use schedule 40 or schedule 80 electrical conduit. You may not use schedule 40 or schedule 80 water pipe.
4) Yes, you can connect schedule 40 to schedule 80.
5) Yes.
 
  #15  
Old 04-07-04, 01:12 PM
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Originally posted by msulliv3

Based on my measured distance of 225 feet, vs 150 feet estimated (bad eyes, I guess), I plan to go with 4/3 with ground. However, can't seem to find it, except at specialty places via special order....cost shocked me (no pun intended)...about $2300 per 1000 feet for UF.

Looking at going with conduit and pulling it. Questions:

1) Can I use plain THHN 4....3 wires (hot/hot/nuetral) and ground??

2) Will go with at least 1.5" PVC even though can apparently go smaller...want to ensure it pulls through. Any problems here??

3) Does the conduit have to be schedule 40, or can regular water line PVC be used??

4) Does schedule 80 PVC that I will use above grade bond to Schedule 40 and white PVC??

5) Is #8 for ground sufficient for this set-up?

Thanks in advance!
You can buy individual conductors size two awg aluminum that are listed as UF cable. You then run three of them in the same trench together with a number six aluminum Equipment Grounding Conductor (EGC). This will allow you a running load of up to fifty amperes on the barn panel without exceeding 3% voltage drop in the feeder. If you will actually need sixty amperes of load in the barn you will need to increase your wire size to number one aluminum and your EGC to number four aluminum in order to keep the voltage drop under 3%. A total voltage drop of 5% will avoid burning up your tools and compressor with under voltage running. Limiting the feeder voltage drop to 3% leaves you up to 2% for the voltage drop in the branch circuits in the barn. The US NEC requires that you increase the size of the EGC in proportion to the increase in size of the current carrying conductors. It will be a lot easier to lay the individual type UF conductors in the trench than to pull that long of a conduit run. If you stay with conduit then use rigid metal sweeps for the nineties at each end of the trench. You connect those to the schedule 40 PVC by using female threaded adapters between the metal sweeps and the PVC. The top of the metal sweeps must be eighteen inches below grade so your trench will have to be deeper. The reason you use metal elbows is that the pull rope or the wires themselves can cut right through the inside of the schedule forty PVC elbows during a hard pull. The difference between schedule forty and schedule eighty PVC is it's internal diameter. The outside diameter is the same and they use the same couplings and connectors. The white water and waste line PVC pipe is thinner and less resistant to physical damage so please don't try to substitute it for conduit. You must call for inspection before back filling the trench. If you want to radically improve the grounding of both buildings you can substitute a bare number two copper conductor that you bury at the same depth as your water line for the aluminum EGC. That much bare number two copper makes an excellent grounding electrode.
--
Tom
 
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Old 04-13-04, 06:31 AM
msulliv3
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Thanks John and Tom, much appreciated!

Leaning towards the #1 aluminum, direct bury. Aluminum is quite a savings ($0.37/foot vs. $0.86 for #2 copper single conductor). Combined with the conduit it is almost a $1.80 per foot savings...or $400 in my case.

4 questions:

1) A supply house by me has what they call a USE rated single conductor direct bury (both copper and aluminum)......I assume this is the stuff??

2) Just want to confirm it is best to bury BARE #2 copper for the ground. I had planned to use #4 USE copper (supply house recommendation), but will go with the bare #2 if that will improve the systems robustness.

3) If bare, can it run bare through the house to the house panel, or do I need to protect it (55 feet).

4) The 60A double pole I will attach to in the house panel (Cutler) seems to be 'rated' for #2 to #8 wire. No one has been able to say for sure. Guessing I can get #1 Aluminum in....just want to make sure I'm not creating any problems doing so.


The site work is done, the barn going up late this week, early next, and I have most all the wiring materials.

Can't thank you all enough!
 
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Old 04-13-04, 09:21 AM
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Mike,

I think that you are well on your way to providing a good, solid 60A subpanel in your pole barn.

That said, something just doesn't sit right with me.

You started out planning on using 6-3 copper for your 60A panel; this is the bare minimum that you could use.

You then decided to upsize to 4-3 because of voltage drop over distance.

Now the plan is to use #1Al, rather than #2Cu...the #2 size because this would permit single conductor direct burial, and the #1Al for reasons of voltage drop at 60A. You are now considering rather larger conductors than your original plans.

You really need to consider what your actual loading is. On the one hand, you have this 30A compressor, combined with a few lights and some other miscellaneous loads, in a fairly large pole barn. This seems to me rather lopsided; one _big_ compressor, but no other significant power tools? Are you ever going to use a welder, or other equipment? Do you simply happen to have a much larger compressor than you really need? Have you ever simply listed what things you _might_ be running in the barn at the same time? Electric heat, perhaps?

On the other hand, maybe you don't need all that much power. Perhaps the compressor is only going to run now and then, and you don't have other tools that you will be operating. Perhaps the maximum continuous loading will only be 15A, with the compressor running 'now and then' pushing the load up to 45A...and perhaps the compressor will be used infrequently enough that you could comfortably deal with the lights flickering a bit whenever it starts.

Sit down and think about what sort of power use you will have in the barn, what sort of power use you could reasonably anticipate in the future, and what sort of power quality you can accept. Write a short essay Based upon your power usage, Your choices range from #6Cu UF (direct bury) or #4Al, to conductors in conduit, to #2 or #1 single conductors direct bury. The only significant problem that I see with any of the direct options is that if you actually need more power, you will have to rip it out of the ground and replace it. You have to balance the possible future replacement cost with the increased up-front cost for conduit.

Finally, be on the lookout for 'dual rated' conductors. If you wanted to buy 'THWN' wire, it would be hard to find and expensive. But most THHN wire is also rated as 'THWN' wire, and can be used as THWN wire...but it gets listed in supplier catalogs as THHN. Also cables in different size ranges often fall under different names with different sets of applications, but for your application the differences are not relevant. You need to check with the manufacturers. If you can't find 'UF' cable in the size you need, look for 'USE' cable. Some types of cable may or may not be used for direct burial, depending upon manufacturing specifications. Even some 'BX' type cable can be direct buried...though most will rust and is prohibited for direct burial.

-Jon
 
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Old 04-13-04, 12:37 PM
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Originally posted by msulliv3
Thanks John and Tom, much appreciated!

Leaning towards the #1 aluminum, direct bury. Aluminum is quite a savings ($0.37/foot vs. $0.86 for #2 copper single conductor). Combined with the conduit it is almost a $1.80 per foot savings...or $400 in my case.

4 questions:

1) A supply house by me has what they call a USE rated single conductor direct bury (both copper and aluminum)......I assume this is the stuff??
I don't have a code book with me today so I'm not sure about using the USE as Type UF. You may find that it is dual listed.
2) Just want to confirm it is best to bury BARE #2 copper for the ground. I had planned to use #4 USE copper (supply house recommendation), but will go with the bare #2 if that will improve the systems robustness.
The use of the bare number two CU as the equipment grounding conductor will improve the grounding system of both buildings. It would improve it even more if it is buried deeper such as running it at the water lines depth of bury.
3) If bare, can it run bare through the house to the house panel, or do I need to protect it (55 feet).
All four conductors will require protection were they run through the house. You will have to run them in some form of conduit. Electro Metallic Tubing (EMT); which is commonly called thin wall conduit in some parts of the country; would be the best choice. I'd have to look up the size you would need but in all of the larger sizes you can buy manufactured 90s & 45s so you don't need to know how to bend the stuff. Were you make the change from EMT to the schedule forty PVC that you use to protect the UF/USE until it is two feet underground you will need to bond the EGC to the end of the metallic conduit. You may be able to save some money by running the trench around the house to were your panel is. This will minimize the length of the interior run that needs to be protected by conduit. If your service comes underground to the house be careful less you hit it while trenching. Call miss utility the number of hours ahead that your state requires. They will mark the location of the utilities for you.
4) The 60A double pole I will attach to in the house panel (Cutler) seems to be 'rated' for #2 to #8 wire. No one has been able to say for sure. Guessing I can get #1 Aluminum in....just want to make sure I'm not creating any problems doing so.
If the breakers lugs are only listed for number two conductors then you may need to rent a high pressure hydraulic crimper in order to crimp tail lugs on to the wire. These so called high press lugs will fit on the wire but the tale coming out of the lug is like a smaller wire that you can then fit in the breakers terminals.
The site work is done, the barn going up late this week, early next, and I have most all the wiring materials.

Can't thank you all enough!
 
  #19  
Old 04-16-04, 01:29 PM
msulliv3
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Finally sorted it out. Got single conducter dual rated THHN/THWN #2 copper for $0.42 per foot. Will pull it in 1 1/2" Schedule 40 conduit. Going to use #4 stranded copper, bare , for the ground.

One last (hopefully) question: Just want to confirm that I must protect the ground (bare) from where it leaves the trench and makes it's way through the house to the panel (50 feet)?? Ditto on the barn end...from the trench to the barn panel. If so, plan to use 3/4 Schedule 40 as the 3 #2's will be continuous from house panle to barn panel.

Only minimal change in planned usage....just want to ensure no problems. Would rather spend a few$$ more now on the larger wire than have to replace it later.

Just a compressor which is used infrequently, and some hand tools (likely a table saw one day). Plus, I did end up with 25 lights (2x32W T8 flourescent). Also have an RV that I will hook-up a couple times a year to get ready, but the fridge/freezer is only 10A.

Thanks again, about a week away!
 
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Old 04-16-04, 09:05 PM
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All conductors / same raceway.

All of the conductors of the circuit must be run in the same raceway. So if you use PVC conduit you have to run the Equipment Grounding Conductor (EGC) in the conduit. What I thought you were talking about was running the individual UF or USE conductors buried directly in the trench without conduit protection. If you did that you could change you're EGC size to #2 bare copper so it would function in the dual role of conductor and electrode.
--
Tom H
 
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Old 05-17-04, 08:27 AM
msulliv3
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Just a quick note to all who helped me out here. Project is done, and everything went perfectly! John, Hornetd and Winnie: Thank you all so much for you time (and patience).

Time is money:
Research and reading......100+ hours over a month or so.
Run the conduits (4)......6 hours.
Pull all the wires (now I know what apprentices do!), and set-up barn panel.....8 hours. (Had a helper for this...commercial electrician).
Running the circuits, installing all the recepticles (33) and hanging all the lights (25).........20 hours.

Satisfaction of learning something new, doing it myself, saving a ton of money, getting the quality appearance I wanted and showing it off to friends/neighbors/family........priceless.

Thanks again!
 
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