Generator Interlock Install

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Old 11-17-09, 04:31 AM
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Generator Interlock Install

I had an electrician install a generator interlock kit in my Square D Homeline panel. It turns out my 200 amp panel and sub panel were both full so tandem or piggyback breakers were used to free up space for the 30 amp double pole generator breaker. My tag on my panel states that the panel is a 30 circuit 40 circuit max so the electrician said that tandems could be used. The problem was that the tandem breakers did not fit into the spaces he made available by moving other breakers around so what he did was "chip" away the plastic on the back slot of the breaker to make the slot longer so it would seat down onto the bus bar. After doing a little reasearch I discovered that there are spaces near the bottom of the panel that are made for tandem breakers. My question is this...should I have this electrician return and do this the right way or is what he did OK? I know technically what he did was wrong but is there any danger issues to what he did? I do not have any more plans to add future circuits so I will not overload the panel by adding more circuits that the panel is rated for.
 
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Old 11-17-09, 08:56 AM
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Originally Posted by tmlmcc View Post
The problem was that the tandem breakers did not fit into the spaces he made available by moving other breakers around so what he did was "chip" away the plastic on the back slot of the breaker to make the slot longer so it would seat down onto the bus bar.
Did you ask to see his license? This is not what a professional would do.

Originally Posted by tmlmcc View Post
My question is this...should I have this electrician return and do this the right way or is what he did OK?
It's not OK.

That would be your call. I'd rather have someone else fix this "work" as I'm very suspicious of the quality of it. Document everything that you can find, with pictures and ask for all the old (the "modified" breakers) parts. Otherwise I'm sure they'll find their way into another installation.

He should not be modifying a breaker in any way. He's also not complied with the panel manufacturers instructions. Therefore the installation does not meet Code. At the VERY least the breakers NEED TO BE REPLACED with new unmodified ones. If he "modified" the panel, he's buying you a new one too.

Originally Posted by tmlmcc View Post
I know technically what he did was wrong but is there any danger issues to what he did?
Yes. The panel is designed in a certain manner. If the breaker does not fit correctly, regardless of the "chip" he broke off, then you risk a poor electrical connection = heat = FIRE!

Originally Posted by tmlmcc View Post
I do not have any more plans to add future circuits so I will not overload the panel by adding more circuits that the panel is rated for.
A couple of tandem breakers are fine, as long as the panel supports them. If you need to add many more items in the future I'd suggest a subpanel.
 
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Old 11-17-09, 09:17 AM
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Just to expand a bit in my opinion the electrician should have suggested a transfer panel. Did he? Besides the fact that interlocks are not as safe and may not be permitted in some jurisdictions in the case of an already full panel that just makes sense at least to me. He did install a proper inlet didn't he?
 
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Old 11-17-09, 09:54 AM
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Your panel is a 30/40 circuit....meaning you can have 30 single pole circuits if you use full size breakers that are single pole. Or you can have 40 circuits using 20 full size single pole breakers in the upper part of the panel and 10 tandems in the lower part of the panel.
The homeline tandem breakers have what is called a rejection feature that keeps them from being installed in the upper part of the panel. This is what your electrician removed so that the tandem breaker would fit where it isn't supposed to be installed. The idea is that the maximum circuits is 40 so if you put tandems in the spaces not designed for them then you could create more circuits than the panel is designed to support. So you are technically correct this wasn't supposed to be done, however if the panel spaces that accept tandems were already filled with tandems then the only choice he had was to remove the rejection feature if he wanted to make room for tandems in the upper part of the panel. This attached image is basically what is going on with tandem breakers vs full size single pole breakers. Homeline is pretty much identical to this and requires the notched bus stab to allow a tandem to be installed. It is a 100% code violation to install a tandem where it should not be...for what it is worth I don't think you have any major safety issues since the breakers are essentially the same and only a small plastic tab separates them apart from one another. lt sounds like the only way to correct this would be a sub-panel.

 
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Old 11-17-09, 10:18 AM
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I agree with the previous post in that I don't think you should have the same guy fix this. It is exceedingly common knowledge amongst electricians that tandems only fit in the bottom slots of a Homeline panel. These are not specialty parts -- if he was a pro he really should have been familiar with the panel. Either that or he did know and intentionally defeated the rejection tab which is an even worse problem in my opinion.

The tandem breaker in an upper slot is probably not a safety issue as the slots are basically identical up and down the panel. However the panel was designed and UL tested to only have tandems at the bottom so it is contrary to manufacturer's instructions and the panel's listing to put a tandem at the top therefore making it a code violation. I'm actually quite surprised the inspector didn't red tag that breaker, again because everyone in the industry knows where tandems go in Homeline panels.
 
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