If I want to run 2 circuits to a detached building in the residential setting, do I have to install a sub panel? I say you do???

You can run a single multiwire feeding 2 120v legs but not 2 separate circuits ... the way I see it.

Wouldn't 225.36 Exception Apply.

Ernie- 225.30 limit's you to one supply with additional supplies for special conditions and residential homes can't qualify for any of these special conditions. So at best we could run a multiwire branch circuit and call it one circuit like Greg says. And I agree.

I think the real intent is that all remote buildings get a panel, ground etc like an "HO guage service" but they make an exception for the guy who just wants a light and a receptacle in his shed. It probably makes a few less orange cords strung through the trees.

Now the obligatory "gee whiz" question.
If the feeder is #10/3wg with a 30a sub panel, what size wire do you run to the ground rod?

And the "obligatory" answer is minimum #8 cu.
I liked that word"obligatory" so I thought I'd use it in the answer, must be the inspector in me. Could use #6 AL if you could figure out some way to keep it 18" above the earth.

Do you think Table 250.66 note 2 might allow you to use a #10 here ? Using the argument that the feeders to the subpanel are not Service Entrance Conductors and thus the "equivalent" size service entrance conductors to feed the load would be (is, in fact) #10.

How about if I connect the two structures with a fence?

I don't think the fence can make a difference. If joining 2 structures with a fence creates a single structure than I live in my neighbors house. Or does he live in mine

LOL

Ian How can I argue with a simple straight forward answer like that.

I wish all NEC issues could be made as clear to me as that.

Bob

Thanks Bob, but just curious do you think it could be argued that note 2 of table 250.66 would allow a #10 GEC for a 30 amp sub in a detached building?

No I do not believe note 2 will provide any relief in this instance.

I believe that, for a sub-panel, you're stuck with #8 to the ground rod. Remember, the ground rod is there for lightning, and has little to do with the service size.

The introduction to the code make it clear that the code is not a design manual, nor is it intended to allow for future growth, etc. With that in mind, I submit that, as a professional who is paid for his judgement as much as anything else, you should make these allowances, and exceed code minimums.

That is, run a big pipe -1" at least- and mount at least an A/C disconnect....at some future date, either the wire will go bad, or the customer will want more. How many garages are really workshops, after all? The $$$ for this improvement over code are minimal, and reap huge dividends down the line.
Or do you like digging? :-)

Bob, the operative question is "did you bond the fence?" If it is bonded at both ends you have a metalic path. Otherwise it is not an issue.
You can even make it more interesting. If the fence is now a wall with a footer (>20' of steel) do you have to stub up a grounding electrode conductor while the steel is "available"?

Greg


Yeah that is kind of a separate issue to what I was half joking about.

A simple breezeway connection between these buildings would change the rules.

Why wouldn't a wood fence do the same thing if connected to each building?

It is just an odd rule.

But as you said the rules are the rules.

Bob

I guess I actually try to see the hazard addressed when I look at rules. I can see "bonded" metalic paths being an issue because you are paralleling the neutral down that metalic path. If this is an unbonded piece of metal it is not really a path. The only path back is down the grounded wire in the 3 wire feeder.

George
225.36 Exception :for Garages and outbuildings on RESIDENTIAL proprety a Snap switch or SET of 3way or 4 way snap switches Shall be PERMITTED as the disconnecting means.
So by that sentence why would Residential not apply????
So Why couldn't two Snap switchs be used as disconnects???Or even a 2 pole switch???
If this is a Mulit wire branch cicuit I feel there'd be no problem.

[This message has been edited by Yoopersup (edited 05-08-2005).]

[This message has been edited by Yoopersup (edited 05-08-2005).]