ECN Forum Forums Code Related Discussion NEC & other Code issues Wiring a barn 230 feet from panel

what is the grounding application needed for the sub panel. I will be running #4 for the hot leads #6 for the ground and neutral, the sub panel will have room for 100 amp or less. Your help is much appreciated!

Steve, I assume you are using copper?

At best the 4 AWG is rated 85 amps and you can round up to a 90 amp breaker.

Voltage drop may be a real issue if you actually start using more than 60 amps.

Once at the barn do not forget a disconnecting means and a grounding electrode system.

You have to do the same things as you would for a new house service.

Your best bet here is to look at 250.32 as it has all the grounding requirements for a separate building.

Bob

Bob, thanks for the reply yes I will be using a ground as well, with #4 for the hots and #6's for netural and ground thats ok for my load up to 60 amp's ? Its going to be four outside lights and eight outlets inside but,future was a concern for a coral ring about another 75 feet from the sub. Question also Bob was the sub panel will I bond the neutral and ground on the panel or use same application as Main Panel. Thanks for your seasoned advice Bob, I am a Newbie with my license in Ca. but love the trade its the BEST! thanks again I will check those codes you said

This is a typical application that is bungled the first few times you do it.

A few pointers for those who haven't done it before:

Make your ditch DEEP. Two feet to the TOP of the pipe, minimum. We're not controlling lawn sprinklers here. You want to be under almost everything but the sewer line.

Run in pipe- BIG pipe. Later, when you need to pull in bigger wire, you will thank yourself. Your choice is either to run pipe once- or dig the same ditch several times. Murphy's law, you know.

When you get to the building, come up on the outside; place your disconnect there. Then feed to an inside panel. You want these wires in pipe also. (Too often the inside gets covered up- then later you want more breaker spaces.)

As a separate building, you need a ground rod, ufer, some sort of GEC.
Even though you have a ground rod, you still need a ground wire to connect this panel to the ground buss at the panel feeding it.

Even though the rules may allow you to down-size the neutral, this is an idea fast falling aside, as power quality becomes an issue.

All considered, for this application I'd run 3-#2's and a #4 ground...in 2" PVC, using long sweeps. I'd size my panel and disconnect at at least 100 amps, and fuse to 60. (I'd also want a breaker at the source). There would be no "main breaker" in the new panel.

Over-engineering? Maybe a little- but it's your house, isn't it?

Reno, thank you.................Ask a question you get a answer without the Drama..........I apologize to you Jon if you read this. No hard feelings winnie

I hope no hard feelings either way. This is a place to learn, a very good place to learn. Far better to ask questions and look like you don't know as much as you do than to not ask questions and demonstrate that you don't know as much as you should

-Jon

Steve, reducing a neutral at 200'+ is a bad idea. Although allowed by NEC, is just a poor design element. Whats saved in copper can be problematic down the road IMO. Not to mention voltage drop will be bad at the distace you stated anyway. And there are options for grounding and bonding of neutral in 250.32 (Same as a service with an electrode and no ground paths between buildings, or as a sub-panel with an EGC sized to 250.66)

Hey wait, didn't everyone say these things already?

Gentlemen, as you can see I have pruned out some posts in this thread, including my own.

Steve IMO you overreacted, we are a friendly bunch that are concerned about electrical safety.

Try not to take things personal, take them as advice from some very educated folks that are trying to help you for free.

If anyone has questions about my actions feel free to email me using the button above my post.

Bob

Now back to our normal diet of electrical talk.

Reno I am just curious (not critical) of a couple of your comments.




Why would I want to come up outside to a disconnect only to pipe into a panel inside?


Personally I would come up inside the building or up outside with conduit to an LB into the building.

In either case I would use a main breaker panel at the barn and save the cost and installation of the disconnect.

Steve I fully agree with the rest of Reno's comments, go deep, go big you will not be sorry in the future.

At 230' 2" PVC would be my choice, 1.5" PVC is the smallest I would consider for the power and while the trench was open I would be thinking about running a spare 1" - 1.25" for whatever. All this changes if your farm includes a backhoe, then I would not be as concerned about re-trenching.

I also agree that the 6 AWG neutral could be a problem.

Good luck and stay calm dude.

Bob

We should also clarify the bonding issue in this panel.

Under 250.32 you have a choice: you can run just supply conductors (no equipment grounding conductor) and then bond this panel just like a service entrance panel, _or_ you can run supply conductors and egc, and _not_ bond ground and neutral in this panel.

If you go the 'service entrance' route, then you must not have any metallic paths between the buildings other than the electrical supply. No pipes, no fences, no phone wires, no zipline This is because you don't want 'objectionable currents' flowing in these metallic pathways.

I believe that over long distances the service entrance approach is better from the point of view of lightning protection, but don't have hard evidence to back this up. Since there usually are other metallic pathways, the choice is usually forced.

-Jon