OT - Electrical Question - Very OT

[Mike Marlow]

Since there's been so much talk of electricity and things electric lately, coupled with the fact that we have more than a couple electricians who also hang out here as woodworkers, I'd like to throw a question on the floor.

I was asked about an unusual configuration this morning. A friend wants to hit the side of a garage with a 200A standard residential service. Coming out of the meter channel, he would like to branch off to two separate 200A locations - a 200A service panel in the house (some distance away - not sure how far), and a 200A service panel in the garage itself. Presumably, if this is even possible, it would require a 200A disconnect after the meter channel and before both of the service panels.

I've never encountered a request like this before, so I'm not sure if it's even possible. If it were anything else (lesser ratings), I'd suggest hitting the garage in the normal way and feeding the house off of the garage. What I'm uncertain of is if you can feed the house with a 200A breaker in the garage panel, since the total service entrance is only 200A. Hell - I'm uncertain if 200A breakers are even available for a standard box.

[Doug Miller]

I think I'd run that past the local inspection authority...

I like your way better. There's no problem, Code-wise, with feeding the house through a 200A breaker (if it's available), as long as the wires are rated for

200A.

Might not be, except as main breakers. A 200A lug kit might work, though: it fits in the same space as a double-pole breaker, but just provides take-off lugs. The overcurrent protection comes from the main breaker, so the conductors would have to be rated for an ampacity at least that of the main.

-- Regards, Doug Miller (alphageek-at-milmac-dot-com)

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[Mike Marlow]

Thanks Doug. I've never seen the lug kits before, so that's new to me. There's no problem in getting the right size conductor put to use - except for the nasty of trying to bend 0000 wire in a panel. Then there's the question of getting the same wire into the neutral and ground buss. Most don't come with sizes to accommodate another 0000 besides the entrance cable... at least to the best of my knowledge. I'm not liking this request. Maybe I should have slept later this morning and missed this phone call.

[Todd Fatheree]

I'll just throw one thing on top of Doug's comments. As he said, you want to run this by the local inspector. In my little municipality, you cannot run service directly to a detached garage. You have to drop it to the house, then feed the garage from there. YMMV.

todd

[Doug Miller]

DAGS on "subfeed lug kit".

Well, if you go copper instead of aluminum, you can go down to 3/0... :-)

I feel your pain.

-- Regards, Doug Miller (alphageek-at-milmac-dot-com)

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[Mike Marlow]

'Preciate the comment Todd. Here, it's not a problem. It's done commonly. In fact, there are no local codes here - everything defaults to NEC. Largely, that's a blessing.

[Robert Bonomi]

Echoing the other advice -- run _whatever_ you propose by the local inspectors

*first*.

THAT said, There _is_ a relatively straightforward way to do this.

make the 'service drop' 250A, not 200.

Immediately below the meter, put in a *FUSED* disconnect switch. With something 'larger than 200 A', and 'less-than-or-equal to 250 A' for the fuses.

*NOW*, both the panel in the garage, and the panel in the house are 'sub- panels'. they do -not- have to have a 'main breaker', to be code-compliant, but I _prefer_ to have one, nonetheless. Code requirements are that such if you have protective devices on *both* ends of a wire, the downstream 'interrupter' be smaller in capacity than the one on the upstream end of the wire. (That's the reason for the 250 A service drop, you can fuse it appropriately, and use the 'standard' 200 A 'main breaker' in the 'sub panel'.

It -may- be necessary to put a junction box "below" the disconnect, where you splice the two runs from the two breaker panels, and then run a single wire up to the disconnect. Modern code _is_ 'fussy' about any splices inside the interrupter enclosure itself. *OR* having two wires on the terminal.

This kind of approach *should* be code-compliant, wherever you are, But _check_, to make sure.

You'll need to up the feed wire size by one gauge, to accommodate the 250A service, vs 200 A. Both from the meter to the disconnect, and from the disconnect to each breaker panel.

In copper, #3 is sufficient for 100A service, so 200A service would be ok on #0. 250A should only need #2/0, it seems to me. Maybe 3/0 if you're dealing with 'long runs'. Of course, if it is AL feedwire, the wire-size requirements do go up a couple of gauges.