How to wire generator input to two panels


Old 10-25-16, 07:36 PM
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How to wire generator input to two panels

Hello - New to this forum. Hope someone can help. I am looking to wire a generator input to two 200 amp panels (positioned side by side each other) via interlocks (assuming one for each panel). Looks to be straight forward process for wiring to one panel but I'm not sure how to connect to a second panel as well. I have a 7000 watt portable generator and just looking to have this option for extended power outage situations. I know that we'll have to be selective in terms of what circuits to turn on while under generator power but like this flexibility versus a transfer switch. Can this be done properly and safely? Have bought a 30 amp generator input, planning to use 10/3 wire w/ ground, 30 amp double pole breakers, and an interlock for each panel (made to fit my GE Powermark Gold Panels). I've heard this could be done by splitting the line in a junction box coming from the input and routing all 4 wires to each panel but I'm thinking this could result in too much amperage going to the generator (generator does have a 30 amp breaker as well). Read another suggestion to run input wiring to interlock breaker on panel #1 then run the 2 hot wires from another breaker (presume another 30 amp breaker) in panel #1 to the interlock breaker in panel #2. Thinking this option makes more sense as it would limit total amperage draw of both panels to 30 amps, right? Also, hearing issues around bonding neutrals or grounds which I'm not familiar with. Appears both panels connect to meter directly behind panels on outside wall. Would greatly appreciate any help here. Thanks in advance!
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Old 10-25-16, 11:29 PM
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Welcome to the forums.

Just to touch on a few things....

The generator is protected by its own 30A breaker.

Make sure your genny uses a 14L30 plug and receptacle. That's the 30A system.

A 7000w genny is capable of putting out 29A at 240v.
Technically #10 is large enough but if it's a long run... I'd consider using #8 wiring.

You'd need two 2P30 breakers and two interlock kits.
The wire from the genny would be split in a j box before the two panels.
Old 10-26-16, 04:40 AM
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In addition to Pete's comments....would it not be easier to install a Generac type switch gear to control the specified circuits? You will be terribly limited with that small a generator as to what you can run. By no means could you run anywhere the load capacity of the 400 amps you have. Just an idea that could simplify things.
Old 10-26-16, 07:15 AM
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Old 10-26-16, 08:24 PM
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Thank you for the guidance. Does anyone know if interlocks are legal for use in NC?
Old 10-26-16, 08:31 PM
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Just to confirm...

In this first pic the generator input box has the feed split and going to each panel.

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In this next pic the generator input box feeds one panel, then another breaker in the same panels feeds over to the second panel.

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Which one would be the correct way to wire the two panels to the generator input?

Using a 30amp Input box, 10-3 w/ ground wiring, 30amp 240v breakers. The wire length is only about 24" to each panel, as the inlet box will be on the wall behind the panels, beside the meter base.
Old 10-26-16, 08:58 PM
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My vote is picture one. It uses one less circuit breaker and gives you the option of powering either panel from the generator while leaving the other panel connected to the utility,

This option requires the use of an approved lock out transfer device on both panels. Whether or not lock out transfer devices are allowed in your jurisdiction would be a matter for the LOCAL code AND the utility to rule upon.
Old 10-27-16, 02:56 PM
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Go with picture #1. I'm pretty sure picture #2 very well may be a code violation. If nothing else it makes it pretty confusing for someone trying to lock out the service.
Old 10-08-18, 09:01 AM
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I'm just researching the same question. Can we touch base to compare notes and see which way you went?

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