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n175h 11-19-2011 05:00 PM

building a main and sub panels for 2 remote buildings
 
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Ok, here goes.

I’m a newbie and have been trolling for a while. They say knowledge is power, but a little knowledge is dangerous. Hopefully, I’m beyond that. I’m planning on building a shop building on a lot I own, then later planning on a new home about 80’ away. My electric plan is as follows:

Electric service main: (shown in the attached picture) Install a 225 amp raintight main panel with a 200 amp breaker containing slots for branch circuits on a framed rack about 27’ from the shop building wall. This rack will be about 8’ from the power company pole and 4’ from my property line, and it will right in front of a 6’ wooden fence in front of my shop building and in sight of each other. It will also be unobstructed and within sight of the future house. My plan is to go underground with the utility’s service from the pole to the meter can on the rack per utility’s service specs. Those can be obtained with an easy phone call. The main will have a 125 amp breaker to feed the shop sub panel and a 125 amp breaker to feed the future house sub panel. Next to the main will have two 8’ copper rods driven in the earth at 6’ apart tied together with #6 copper wire and bonded to the neutral buss in the main’s cabinet clamped with an EK16/EK17 clamp http://www.erico.com/products/EK16EK17.asp at 6” below the surface.

The underground conduit buried 18” or deeper to the shop sub panel will be grey sch40 pvc 2” x 27’ long, two 90 bends. Exposed pipe will be sch80 pvc. Pertinent pipe markings will be laid upward so the inspector can see them. PVC pipe that passes through the concrete beam will be rapped with a layer of foam to allow a slightly loose fit between pipe and cement. Wire size from main to sub will be three 1/0 thhn and one #6awg ground conductor bonded to the neutral buss in the service main. At the shop building a 20’ ” rebar will be tied to the bottom beam steel 2” above the dirt bottom of the beam in the slab before the pour and stubbed out of the floor below the sub panel location as a CEE (concrete encased electrode) grounding electrode. No other grounding rod shall be located in or outside the building.

The sub panel in the shop shall be rated at 150 amp or greater with a 125 amp circuit breaker acting as a panel disconnection. The neutral shall be isolated from the panel. The 6awg wire from the main shall be bonded to the cabinet via a separate buss bar and bonded with a second #6 wire, clamped to the CEE rebar with an EK16/EK17 clamp.

The shop outlets shall consist of approx 10-15 20amp 120v branch circuits, 3 20amp 240v circuits, 2 50amp 240v circuits. 20’s will be wired with #12thhn. 50’s will be wired with #6thhn. All wiring in EMT. Grounds for 20’s to be #12thhn green. Grounds for 50’s to be #10awg green. Lighting system to consist of three rows of 5 each per row of f96T8 two lamp fixtures making a total of 15 fixtures.

General workmanship shall include all junction and switch boxes to be pigtailed with a ground wire tied to the grounding electrode system. Feeder wires appropriately marked with ID tape for hots, neutrals, grounds. All raceways clamped within 18” of any J box. All breakers labeled to identify circuit location. All feeders and wiring is copper.

This is my plan. Actually it’s the proposal I have to give to my inspector before permitting. I’m held to a higher standard since I’m a homeowner and not a licensed electrician. In all the construction work I’ve done, if the job has a licensed electrician the inspection is cursory at best, but if it’s a homeowner, oh my, look out. He will gig you on something. The one place I might get a frown for is the location of my main service. I don’t want it on the wall of the building because it will add some underground pipe under a driveway and some other issues. Also, it eliminates the need for a temporary service during construction that will save me a few hundred $$$$.

I figured I throw this out to the forum. In browsing I’ve noticed you guys are pretty hard on a lot of novice questioners, but I figured I’d take a chance and see if I could get some free advice. So, is there any additions or changes that I should make before submittal?

Thanks,
David

Techy 11-19-2011 05:11 PM

it all looks good to me, except for the 8' T8's, those things are almost worthless.

Code05 11-19-2011 05:22 PM

Looks good. I did not see any problems on my first pass.

Is the shop feeder wire copper or aluminum?

Why do you want a 150 amp rated panel for 125 amps? Waste of money.

Does the shop have heat?

n175h 11-19-2011 05:35 PM

Quote:

Originally Posted by Techy (Post 774916)
it all looks good to me, except for the 8' T8's, those things are almost worthless.

I've had great luck with T8's. I've had them on the front of my business awning for 4 years now and they are great for south Texas. They are bright down to zero. Never gets that here.

Code05 11-19-2011 05:37 PM

Quote:

Originally Posted by Techy (Post 774916)
it all looks good to me, except for the 8' T8's, those things are almost worthless.

I am not a fan of them also. I would use 4 footers and 0 degree ballasts.

T1296 HO would work but can be a PITA to bulbs in some places.

n175h 11-19-2011 05:38 PM

Quote:

Originally Posted by Code05 (Post 774926)
Looks good. I did not see any problems on my first pass.

Is the shop feeder wire copper or aluminum?

Why do you want a 150 amp rated panel for 125 amps? Waste of money?

Does the shop have heat?

No heat needed. South Texas. 100 degrees all summer:eek: 80 in the winter

Seems my load calculations needed a 150 amp breaker from this chart.

http://www.electrician2.com/calculat...cpd_ver_1.html

Code05 11-19-2011 05:42 PM

Quote:

I figured I throw this out to the forum. In browsing Ive noticed you guys are pretty hard on a lot of novice questioners, but I figured Id take a chance and see if I could get some free advice. So, is there any additions or changes that I should make before submittal?
Only if someone comes here that is completely clueless and expects a miracle.

You seem to have done your homework.:thumbsup:

Code05 11-19-2011 05:47 PM

Quote:

Originally Posted by n175h (Post 774935)
No heat needed. South Texas. 100 degrees all summer:eek: 80 in the winter

Seems my load calculations needed a 150 amp breaker from this chart.

http://www.electrician2.com/calculat...cpd_ver_1.html

You have a 125 amp shop breaker correct? And a shop feeder breaker in the main panel at 125 amps?

Is the wire CU or AL?

n175h 11-20-2011 12:34 PM

Quote:

Originally Posted by Code05 (Post 774942)
You have a 125 amp shop breaker correct? And a shop feeder breaker in the main panel at 125 amps?

Is the wire CU or AL?

Oops, my bad. The breaker in the main is 125 and breaker in the sub is 125. I misspoke. The calculator calls for a 110 amp breaker for a 30 amp continuous load and 70 non continuous, thus the need for a 125 amp panel, not a 150 amp panel.

All wiring is CU.

n175h 11-20-2011 12:37 PM

Quote:

Originally Posted by Code05 (Post 774940)
Only if someone comes here that is completely clueless and expects a miracle.

You seem to have done your homework.:thumbsup:

I spent days reading these forums and Mike Holt's forum and reading the applicable NEC requirements. I still have to prove to the inspector I know what I'm doing. I wanted a bit of assurance, so that is why I put it out to you guys. I have to do the same thing for my plumbing specs. It's easier; just a toilet and sink and 80' of sewer line to my property boundary.

David

n175h 11-20-2011 12:39 PM

Where do GFCI plugs come into play in this building. Is this a "shop" or "garage"? Do I need to choose my wording carefully on my permit application?

David

n175h 11-20-2011 03:25 PM

Looks like NEC 230.70 will give me the okay to locate the service main remotely from the two buildings.

NEC 230.70 The electrical service disconnecting means shall be installed at a readily
accessible location either outside a building or structure or inside nearest the point of
entrance of the service-entrance conductors.

The more i search, the more answers I find.

David

J. V. 11-20-2011 04:19 PM

I would look into a meter main for the service panel. It is a meter and load center in one. Excellent way to serve the other structure from the outside.

n175h 11-20-2011 04:34 PM

And more searching I find NEC 225.31

Disconnecting means must be installed for all ungrounded conductors that supply or pass through a
building (NEC 225.31). The building or structure disconnecting means must be installed either inside or
outside, within 15 of the footprint of the building or structure. The disconnecting means must consist of no more than six switches or circuit breakers mounted in a single enclosure, in a
group of enclosures, or in or on a switchboard. The allowed disconnects must be grouped and marked to
indicate the load served (NEC 225.34). You should refer to NEC 225 II Section II, More Than One
Building or Other Structure, for other outdoor feeder requirements.

For some reason I'm not differentiating this as to exactly where THIS panel in NEC 225.31 is. Is this 6 space limit for the service main adjacent my meter can? Or is this 6 space limit at the panel on the inside wall of my proposed building? My interpretation is that the 6 space limit is at the service main (which was my planned enclosure), and I can have up to 6 separate buildings powered from it.

Is the "within 15' of the footprint of the building or structure" a local requirement or NEC requirement?

n175h 11-20-2011 04:36 PM

Quote:

Originally Posted by J. V. (Post 775505)
I would look into a meter main for the service panel. It is a meter and load center in one. Excellent way to serve the other structure from the outside.

It's customary around here to hang a meter can and pipe over to the main panel. I can't remember seeing any all in one enclosures. It doesn't mean it can't be done. It's between me and the utility service provider.

David


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