Mostly about gronding and GEC


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Old 04-21-09, 02:43 PM
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Mostly about gronding and GEC

To begin this I have to say from the 70 archive pages that I have read, that it is nice to have so many experienced people answering questions to people they donít even know. Thank you for your time. After all this reading I couldnít find anything about these questions I have.
This is going to be a little long winded. I know you guys and galls like detail. I am trying to get the most out of this small 85 x 100 foot lot for recreational use and living as well. I have a 200 amp service on my main panel, 1984 early manufactured home mobile home, on a raised 24 inch rectangular concrete foundation, it has wood and some kind of plaster board six inch walls. Just so every one doesnít get to erratic about this ďI did a load calc and came up with 60 amp on the summer side and 92 amp on the winter side The main panel is a Gould ITE type panel that had only16/32 spaces There are four double pole breakers, 60, 40, 30, 25. This is a single family dwelling. We are not in a lightning prone area even though we live 2 or 3 blocks from the ocean. We live in a small 650 square foot home with 2 small bedrooms. All Electric. I am thinking about going to a propane fired hot water tank, 25 amp and range, 40 amp, because of the frequent power outages. The city I live in conforms to the International Building Code which uses the NEC. I am my own contractor on this property. The only time I need a permit is if I add a new meter or move inside walls or add more square footage to the home or add a garage and probably add a large propane tank or electrical main transformer.

Last summer I built a portable hoist with a center beam that is 16 feet long that weighs about 350 pounds. The I-beam structure that the center beam sits on is 16 feet long by 12 feet wide by 13 and 1/2 feet tall to the top of the center beam and 4 inch pipe extending it to 28 feet, some day we are going to put corrugated steel panels on the roof and sides. When I built this I was considering the height and width of a car lift into the design. This structure is not on concrete except at the corners of the I-Beam frame for support and are not bolted to it. There are 2 4 inch pipes that sit in the ground as part of the uprights and will be cemented in this summer, but because they are bolted in a way that can be taken apart from the main structure, it wonít need a permit. The total weight of this structure is about 3500 pounds. We put this together ourselves without a large crane. It was tough to do but it did come together. It is bolted with 146 - 2 ľ x ĺ inch bolts plus many other assorted sizes and all of it with 2 coats of spray painted primer with a tarp over it right now. There was over 450 holes that had to be drilled. It took us 8 months at almost everyday to put this together. It has already seen one windstorm of 70 m.p.h. The reason I call this a portable hoist is that if I were to bolt this down to concrete the city would want me to get a permit for a new building, which it is not at this time. If I do put in concrete, I made a big bracket to lift the hoist up off the ground, one leg at a time, so I can put bricks underneath the legs to raise it high enough for the concrete pour. We might just pour concrete over and cover the steel uprights to the height of the concrete.

I found a lug kit for the main panel and added a 200 amp main disconnect meter combo sub panel next to it that has feed through lugs. After we installed this we had brighter lights, evidently I had a loose neutral or two, which could explain why my big screen TV blew up. Forgot to add that this is all copper wire. In both feeds to these main sub panels is and will be 3 -- #4/0 EXPL THHN, THWN, USE wire with #4 EGC. From the new sub panel and the feed through lugs which I plan on using for this to the end of the house is about 50 feet. This is going to be routed through 2 to 2 Ĺ inch electrical non metallic conduit under the house in the crawlspace on the ground and stake it every 5 feet to keep it from moving around. From there I plan to run electrical rigid metal pipe under ground at a depth of 6 inches, with metal 90 degree sweeps, or so, maybe deeper if I have the energy about 20 more feet to a new 200 amp main disconnect meter combo sub panel, it was a pretty good deal on these, that is next to this portable hoist that I built, and will be WOOD post mounted with feed though lugs. I am disabled with a broken right foot so everything I do is on my knees or my butt.. 70 to 75 feet, this size cable is going to be a little rough to pull even with pull points and wire lube. I have most of the wire, 4/0 240 feet, #2 40 feet, #3 150 feet and some #4 about 40 feet, the R-3 service entrance rated sub panels all ready. Just the smaller wire yet to get and the 100 amp R-3 enclosure for the front section. I havenít decided on which panel I will use. MLO only or with a breaker. Depends on if I can get one with the extra breakers like a contractor panel would be at a reasonable price or not.

I have an old transformer welder that will draw as much as 103 amps. AC/DC --stick Ė Tig combo. I will be protecting this with a 100 amp breaker at the post mounted sub panel outside and will be supplied with #2 THWN, USE-2 type wire. I plan on using a 100 amp disconnect switch to the welder and then hard wired from there which again would be mounted to a post and not metal. I do not expect to use this welder except in the summer when repairing an older truck. There will also be 1 dedicated Ė 30 amp receptacle for an RV hookup and 4 - 20 amp outlets, all protected by either a GFCI breaker or individual GFCI receptacle for power tools and maybe compressor. The RV circuits will have #10 THWN and the 20 amp circuits will have #12 THWN, of course black, red, white and green.

From that sub panel that is post mounted I will run to another 100 amp sub panel that is another 30 to 35 feet in front of the portable hoist and will be mounted on the steel frame of the portable hoist. Or I will run next to the portable hoist with some more I-Beam that will be mounted by way of re bar pounded into the ground and that sub panel and receptacles will be mounted to some wood that is bolted to the steel in which case I may not need a grounding rod. That sub panel will have one dedicated RV 30 amp circuit and 6 20 amp circuits for Christmas tree lights and power tools, Plus later another 30 amp circuit for another mig welder that I might or might not use there. I will be running 1 Ĺ inch conduit with 3 -- #3 THWN, MTW and one #6 EGC along the edge of the I-Beam that will be next to the portable hoist and this will also be protected by a 100 amp breaker in the sub panel that is mounted to the post. Oh and just a note to all of this , All outside receptacles will be in water tight type boxes and some will have in use covers.

The feed through lugs at the post mounted sub panel might be used for a generator driven by propane or diesel some day. Or for a new meter connection. and also I will be burying another rigid metal pipe for the generator application, but left with only a pulling method for access. The generator will have to have a grounding rod I think.

I upgraded the cable size to the 2 main sub panels mostly for upgradeability to a 320 amp service if needed, Or to have another 200 amp meter put in, which is OK in this neck of the woods as long as I stay within 400 KWH, Then it jumps up to something like 6 cents per extra or something like that. This setup would have to be installed underground that comes in from one side of the property, the overhead service comes in on the other side of the property I have now. I live on the corner lot. By adding another meter though it would add another 75 feet to the existing run of 75 feet that I will be running to the post mounted 200 amp panel. That way I would have 400 full amps to the property. Plus still have the use for the generator. But I also didnít want a lot of heat built up if the bigger welder was used a lot more at itís 60 percent duty cycle. 6 minutes out of 10 is a lot of cooking power at itís 460 amp output. I have options. I talked to the engineer at the utility company and he told me that the transformer should handle the load of this welder but the cable to the house might not because he said it was only #4 cable. He told me to call him if the lights were dimming when I used the welder. It looks like #4/0 was used from the cable drop to the meter and the main panel. If the lights do dim it isnít because of the cable on my side is too small.

I know I will need a grounding rod at the portable hoist because of the mounting of the sub panel to it unless I do the mentioned above, but, I am not sure if I need a grounding rod at the sub panel that is mounted to the wood posts. From where I sit all of these sub panels and outlets are for temporary use and will not be used all the time. Just like wiring from a main panel to yard lights, or mounting a sub panel to the side of the house for use of a welder or RV hookup, and there fore no GEC would be required. This setup isnít going to an out building as such because it is separate from it. This I think is a very fine line to explore. Will someone give a guess for me about whether or not I need this grounding electrode, grounding conductor and rod. If it does need to be there then will #4 bare copper be used for this application? Or will insulated cable be a better choice if the generator is added to the equation.

One more question, are there any pre made stakes that I would use to stake the PVC under the house? Or is it up to me to find the way?

1949 words later and a big
Thank you very much.
 

Last edited by newkid1; 04-21-09 at 03:03 PM.
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Old 04-21-09, 07:48 PM
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The grounding electrode conductor connected to rod, pipe, or plate electrodes never has to be any larger than #6 copper 250.66(A) (2005)

I have never seen any kind of stakes like your talking about. If your running it through the crawl space, and it has a dirt floor, I suggest getting some 4x4 treated posts. Cut the posts in to 12" pieces and lay them down and bury them half way. Then use some two hole straps attached to the 4x4 blocks.

I will admit, your post is VERY long and I could only skim it. If I missed your questions please let me know.
 
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Old 04-22-09, 06:02 AM
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I too tried to read through but I think some of the detail not electrically related distracted from the true questions.

Perhaps a sketch of the proposed setup would help.
 
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Old 04-22-09, 07:11 AM
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I have a couple of google sketchup drawings, but I am not sure if I can post them here. I think they are propietory to the program. If you have google sketchup than I can email them to you. I do not have post attachments permission yet. The main sub panel that is post mounted that will be sitting next the steel frame. Will this need a grounding rod? Also I thought that because I upgraded the wire size to #4/0, that I would also need to upgrade the GEC if needed as well as the EGC.Then the next sub panel down stream from this. Will this also need a GEC if it does not come into contact with the metal of the steel frame? From my understanding, the welder will be grounded at the 200 amp sub panel by running the EGC to the frame of the welder. Is this correct? These questions about the grounding system, GEC are not about trying to save money. If I have to add them then I will add them. Even though I do not think they are required. Thank you again
 

Last edited by newkid1; 04-22-09 at 07:49 AM.
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Old 04-22-09, 07:24 PM
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Yes, you need a ground rod for the sub panel. The wire does not need to be larger than #6 copper.

Even though the steel frame is not a building, I would treat it as such. Since this sub panel is serving the steel frame area,(hoist, welder, etc) it is my opinion that you should bond the panel to the steel. Your GEC should be based on the wire size of the largest ungrounded conductor.

On the next sub panel, if it doesn't leave the same "building" you will not need a GEC. Only a EGC (unless you use steel pipe).

The EGC is based on overcurrent protection rating not wire size. You will need a EGC sized to the breaker setting for the welder.

The best thing to do is to check with you AHJ.

For posting pictures you have to post them on photobucket and link them here.
 
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Old 04-23-09, 07:36 AM
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Tolyn Ironhand, You are good. That all makes sence to me. I hadn't thought about bonding the panel to the steel frame. even though I thought about doing that at the last sub panel. you see I have to run the cabeling on the outside and at the corners because of the Rv hookups and because the tarp overhangs the steel on the outside. I have the space to run the conduit on the inside of the steel frame, but I don't have the support that I would need to hold the PVC in place,and it wood take up to much room if I did Thank you.
 
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Old 04-23-09, 11:43 AM
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Here is a link to the photos that you requested. I was having some trouble with my ISP, so if you cannot get connected please let me know. Thank you.
Http://www.popswebberbay.com/electrical.htm
 
 

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