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Jason
Jason, Service Technician
Category: Electrical
Satisfied Customers: 4276
Experience:  Over 20 years of experience in all types of installations, troubleshooting, and repairs.
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hook up generator to house through breaker box.

Resolved Question:

hook up generator to house through breaker box.
Submitted: 6 years ago.
Category: Electrical
Expert:  Jason replied 6 years ago.

Jason :

Hello. Thank you for asking your question on Just Answer...

Customer:

trying to install generator through breaker box

Jason :

What is the amperage rating of the main breaker in your electrical panel?

Customer:

30amp

Jason :

You have a 30 amp main breaker? Is this a small older house?

Customer:

let me check main amp

Customer:

sorry main is 200

Jason :

No problem. That clears it up for me. Do you know the output amperage of the generator? Also, what is the brand of your electrical panel?

Customer:

gould panel dont know exact output on gen

Jason :

OK, I have enough information to give you a preliminary answer. Unfortunately, there's no really simple way to connect the generator to the existing panel. Are you open to installing a subpanel beside the main panel, and moving the circuits you want backed up by the generator into the subpanel?

Customer:

sure

Jason :

That's the most common way that we do it. When given the choice, I will set the subpanel up with a 60 amp feed from the main panel. Then I relocate the selected circuits from the main panel to the subpanel. The subpanel will be a Main Lug type panel, not a Main Breaker type panel. However, you will need a double pole 60 amp breaker in the sub to act as a main. You will feed "backwards" through this breaker. Does this all make sense so far?

Customer:

sure does

Jason :

Great. Now, directly below the 60 amp "main" breaker in the sub, you need to install a double pole breaker that is appropriately sized for the generator output rating. Between this double pole breaker and the 60 amp double pole above it, you need a safety interlock device. Let me see if i can find a picture of it Online.

Jason :

This is a Square D model. You can see that it prevents two adjacent breakers from being turned on at the same time.

Jason :

Before you go to the trouble of installing a subpanel, I need to let you know something.


 

Customer:

ok

Jason :

I was unaware (until I searched for that image) that you can get an interlock kit for your existing panel, which works the same way. It will not allow your existing main breaker to be on at the same time you have the backwards fed generator breaker on. The only condition is that you install the generator breaker in the proper location, relative to the main breaker. That would be a lot less work for you, if you can get the proper interlock for your existing panel.

Jason :

Let me see if I can post something else for you...

Customer:

sure would appreciate it

Jason :

Click here

Jason :

If you buy your materials from an electrical distributor, rather than a home center, the counter person will likely be able to help you get the proper interlock device. They will need as much information as you can provide about your electrical panel.

Customer:

thanks for all the help

Jason :

You are most welcome. Do you need any more details, such as specific connection points for each wire?

Customer:

sure

Jason :

You will need a 4 wire cord from the generator. It should have 1 black, 1 red, 1 white, and 1 ground (bare or green). The black and red wires are both hots. They will connect to the "backwards fed" breaker. The white is a neutral, which connects to the neutral bar in the electrical panel, where all of the other whites are already connected. The bare or green is ground, and it connects to the ground bar, where there will already be many ground wires. You can also install a PB 30 box (the "30" assumes the output rating of the generator is 30 amps). There was a picture of it on the page of images that I linked you to. The PB30 would be installed near where your generator would be when you need to use it. You run a cord from the generator to the PB30. And you would need to hardwire from the PB30 to the breaker panel. It's the picture at the top right, with the round lid open, exposing the outlet blades.

Customer:

got it!and thanks again.

Jason :

My pleasure. If you find that you need more help, please let me know.

Customer:

sure will

Jason :

If you have found my answer helpful, your clicking on the Accept Button would be much appreciated. This is the only way Just Answer pays me for assisting you. If you click Accept, you can still communicate with me about this question, at no additional charge. Thanks again for the opportunity to help.

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