Sub Panel Instead Of Generator Transfer Switch - Electrical - DIY Chatroom Home Improvement Forum

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Old 07-12-2011, 09:51 AM   #1
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Sub panel instead of generator transfer switch

I can easily use the "kit" transfers switch from lowes, but was thinking I could save a few $$ and use a sub panel instead. I just wanted to get some feedback from people who have done this. I only need a 5 or 6 circuit sub panel, feed it from the main and have a double 30amp breaker that will connect to the generator feed. I know the safety questions is how to ensure backfeeding will not occur, so the homeowner will need to be sure to turn off the breaker coming from the main. Thoughts?


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Old 07-12-2011, 10:28 AM   #2
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To avoid the possibility of killing anyone by backfeeding the service, you would need an interlock kit that physically prevents the sub panel's main breaker and generator connection breaker from being closed at the same time.


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Old 07-12-2011, 10:58 AM   #3
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Square D makes an approved interlock equipped sub panel.

The blue box store has it for less than $100. Square D QO48M60DSGP
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Old 07-12-2011, 12:06 PM   #4
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The transfer or interlock mechanism is still mandatory and can be part of the main panel (post #2) or part of the subpanel (post #3) or a transfer switch (similar to a pre-main panel transfer switch) in between.

The advantage of not putting a transfer switch before the main panel is that it would be a suitable do it yourself job not requiring calling the power company to disconnect and then reconnect the power.

One style of transfer switching subpanel does not require moving cables from the main panel to the subpanel. Instead individual 12 and 14 gauge wires for perhaps six to ten chosen branch circuits run through a conduit to the main panel and connect to the respective circuit wires and breakers. The generator feed connects directly to the subpanel. Reliance makes some of these.
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Last edited by AllanJ; 07-12-2011 at 12:38 PM.
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Old 07-12-2011, 12:58 PM   #5
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Originally Posted by vtboy51 View Post
so the homeowner will need to be sure to turn off the breaker coming from the main. Thoughts?
Are you the homeowner?
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Old 07-12-2011, 03:02 PM   #6
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The best and most cost effective method is using a panel such as Allanj mentioned. It is available at the big box stores and available in 6 to 12 circuit configurations. Each Circuit "switch" is itself a transfer switch, so the "homeowner" doesn't have to think or remember anything except flipping the breaker to it's alternate position. Being sure to flip off the main doesn't cut it.....a transfer switch or interlock is a MANDATORY requirement, as Allanj has already mentioned. These pre-manufactured panels take care of all those issues.


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