Wiring Mother-in-Law Apt

Chell456May 22, 2013


I am working on creating a mother-in-law apartment in the basement of my house and I'd like to arrange things so that the electrical usage can be sub-metered. So far, this is pretty straight forward as I will have a breaker panel for the house and a breaker panel for the apt. The problem is that the washer and dryer will be shared between the two units.

The best idea I have so far would be to use a 3-way switch (for the washer) which I believe acts like an A-B switch. Flipped one way, it would take power from the house panel and flipped the other way it would take power from the Apt panel. The neutral would be unswitched and would come from one panel or the other - but not both.

The question is, how does this fit with the NEC?

Any thoughts?


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I'm not an electrician, but I'm pretty sure that that definitely wouldn't be allowed by the NEC.

You'd probably need something that switched both the hot and the neutral, like a Double-Throw Safety Switch (see link below).

Or you could install two receptacles (on different circuits) side-by-side at the washer and just unplug it from one and plug it into the other.

Either way, it seems like it would be a pain in the butt and you would frequently forget to switch it over to the proper side.

Here is a link that might be useful: Double Throw

    Bookmark   May 22, 2013 at 1:17PM
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Ron Natalie

You can't do it primarily because the neutral needs to follow the hots in the circuit. Since you say "submetering" you mean that you intend to keep with one service but want to bill your tenant for their use.

    Bookmark   May 22, 2013 at 3:44PM
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Frankly I can't imagine that it would be cost effective nor practical to have some kind of switch. Up the rent by a few dollars per months to cover the cost of utilities and be done with it. Or install a washer/dryer with a coin slot.

    Bookmark   May 23, 2013 at 5:55AM
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This is a common transfer switch application isn't it?

    Bookmark   May 23, 2013 at 9:36AM
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