# Subpanel Ground



## datafan (Aug 27, 2005)

I am bidding a 100 Amp service for a new shed. The shed is 250' away from the house and is not connected to the house with any metalic objects (no water or gas lines etc.). The house is up on a wooded hillside above the shed, it will require 125' of trenched wire across the yard from the house, install a pole and run a stack up it to convert to overhead on the top edge of the steep wooded hill, continue the overhead to a post 75' down the hill and continue overhead to the stack on the shed. 

Finally my question (s).
Per code, do I need to run 4 wire and treat this as a sub panel with no ground to neutral bond screw? 

Or can I just run urd and triplex (3 wires) and sink a ground rod at the shed.
And if this option, do I install the bond screw and tie the neutral and ground together in the subpanel or leave it out? 

Perhaps both methods meet code? If so the second is less expensive.

I don't have my code book here with me and I am not understanding the information I have managed to find online. 

Thanks...


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## mdshunk (Mar 13, 2005)

datafan said:


> Per code, do I need to run 4 wire and treat this as a sub panel with no ground to neutral bond screw?


You only need to run a 4 wire if you have "other metallic paths" between the two structures, and you'd set it up as a subpanel. Even though not required in this case, it is the better option if you wanted to go "above code". 



datafan said:


> Or can I just run urd and triplex (3 wires) and sink a ground rod at the shed. And if this option, do I install the bond screw and tie the neutral and ground together in the subpanel or leave it out?


Yes, if you only run 3 wire, then you must install the bond screw or bond strap. You sink a ground rod out there regardless of which wiring scheme you use. 

There are some special rules for required main disconnects for residential accessory structures that will be of some concern to you. Are you famaliar with those codes?

You mention that you intend to use URD for the underground portion. It may interest you to know that URD is not a code recognized conductor insulation type, and it can't be brought inside the house's panel to hook up to the feeder breaker. Some URD is dual rated as RHH or XHHW, and some is not. The compliant option would be to choose XHHW (aluminium) or THHN (copper) instead of the URD, unless your URD happens to be dual rated.


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## datafan (Aug 27, 2005)

> There are some special rules for required main disconnects for residential accessory structures that will be of some concern to you. Are you famaliar with those codes? .


I think I am ok with it??? We have done many sub panels but always run 4 wires. Is there somthing specific you are thinking about that I may not be aware of with a 3 wire system? 



> You mention that you intend to use URD for the underground portion. It may interest you to know that URD is not a code recognized conductor insulation type, and it can't be brought inside the house's panel to hook up to the feeder breaker. Some URD is dual rated as RHH or XHHW, and some is not. The compliant option would be to choose XHHW (aluminium) or THHN (copper) instead of the URD, unless your URD happens to be dual rated.


I understand what you are saying here. I misspoke using URD, I use something called "sweet briar", I think that's the manufactures name but not sure, we call it sweet wire. It is 3 aluminum wires wrapped together, I don't have a piece here to look at right now, but I believe it must be XHHW??? It is rated to direct bury and also run inside a dwelling.


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## datafan (Aug 27, 2005)

The wire I was refering to is Series 8000 wire. The code name for 4/0 is Sweet Briar, the code name for #2 is Stephans. I don't know who comes up with this stuff???


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## unclemoustache (Nov 20, 2009)

Sorry for bringing back an 8-year-old thread, but I'd like the updated answer to this question. (Maybe I should have looked through the search options more).

I'm wiring up a tiny 2-room cottage on my property that has kit, bath, laundry, etc). I plan to have it as a 100-amp sub panel off my 200 amp service in the house, which is only 10 feet away (probably 60 feet as the wire runs from panel to panel).

Two questions:
1. Is 100 amp enough for this, or do I need to just have a whole separate entrance for this?

2. What about grounding? Do I need a ground rod; or wire back to the main panel; or both?


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## Anti-wingnut (Mar 12, 2009)

Ask on a DIY forum?


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## Seven-Delta-FortyOne (Mar 5, 2011)

unclemoustache said:


> only 10 feet away (probably 60 feet as the wire runs from panel to panel).


 

Are you burying your cable 25 feet underground???


The answers to your other questions are found in the NEC. :thumbsup:


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## Seven-Delta-FortyOne (Mar 5, 2011)

I think this is the oldest thread I've ever posted on.

I want to dig one up from '03. :clap:


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## Red Adobe (Jul 26, 2008)

well what was code then wont pass now anyways LoL


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## unclemoustache (Nov 20, 2009)

Thanks for all your help. I knew I could get useful answers around here.


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## svronthmve (Aug 3, 2008)

You did. Your answers can be found in the NEC.

Or hire someone competent in electrical to guide and/or do the work for you.


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## Seven-Delta-FortyOne (Mar 5, 2011)

Why should I do your load calcs for you, reference dozens of code requirements, alternatives, and special circumstances that may or may not apply to your specific installation, then explain them to you so you can understand how to apply those code articles, then walk you through the job, for free??

And why, if some interweb yay-hoo did all that for you, for free, why the hell would you trust what he said????


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## CarpenterSFO (Dec 12, 2012)

unclemoustache said:


> Thanks for all your help. I knew I could get useful answers around here.


FYI, here on C.T., sarcasm is practically a kiss on the lips.

svronthmve's advice is good. The NEC is pretty clear about grounding and bonding - at least you can usually find the answer for a specific situation.

Anyway, the answers to your questions are entirely "it depends", and if you want to get past that, you need to follow svr's advice far enough that people here aren't concerned that they'd just be encouraging you to electrocute yourself.


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## CarpenterSFO (Dec 12, 2012)

Seven-Delta-FortyOne said:


> ...And why, if some interweb yay-hoo did all that for you, for free, why the hell would you trust what he said????


Because it was free, duh.


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## MTN REMODEL LLC (Sep 3, 2010)

CarpenterSFO said:


> FYI, here on C.T., sarcasm is practically a kiss on the lips.
> 
> svronthmve's advice is good. The NEC is pretty clear about grounding and bonding - at least you can usually find the answer for a specific situation.
> 
> ...


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## Calidecks (Nov 19, 2011)

CarpenterSFO said:


> FYI, here on C.T., sarcasm is practically a kiss on the lips. svronthmve's advice is good. The NEC is pretty clear about grounding and bonding - at least you can usually find the answer for a specific situation. Anyway, the answers to your questions are entirely "it depends", and if you want to get past that, you need to follow svr's advice far enough that people here aren't concerned that they'd just be encouraging you to electrocute yourself.


You must have the balls of a buffalo, to post on this site. Only the strong survive through natural selection.


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## CarpenterSFO (Dec 12, 2012)

CarpenterSFO said:


> ...that people here aren't concerned that they'd just be encouraging you to electrocute yourself.


... by which I mean that no one wants to feel responsible for providing just enough information for you to be dangerous to yourself or others (and the grounding/neutral/bonding situation has good potential for danger).


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