# Use of a single DPDT transfer switch with portable gen



## thew60 (May 21, 2013)

New to this forum, greetings:

I have a 8kW, 10kW peak portable gas generator. Getting estimates for installation of transfer switches. The typical setup is with a 10 circuit sub panel. Recently, an electrician gave me a recent estimate for something different. He offered to install a single double pole double throw transfer switch that would connect to the whole main panel. He explained that I would have to turn off the main 200a breaker as well as the breakers of the heaviest loads: Central air, electric stove, electric dryer, and I would have the ability to run whatever lights etc I would need without being locked in to a selected 10 as long as I did not exceed the 8kW/ 10kW max of the generator.

I have a main panel with 200 amp service mainly for the central air which is 40 amps. 

I have not heard of this type of transfer switch installation. Is it an accepted and code installation of a transfer switch, or is a sub panel mandatory? I want to be safe but this type of installation sounds a bit more versatile than a sub panel. 

Any useful input will be very much appreciated


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## Dqalex (Nov 25, 2012)

You can see the boxes on the Home depot web page. What he wants to do is put in a 3 way throw switch. Its a good system. Very safe. I went with a interlock kit via a Generator inlet box on the outside of my home.


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## KRE (Nov 29, 2011)

A manual transfer switch that has an amperage rating equaling the service entrance has the ability to except a larger gen-set when you up grade. Which you most likely will, over time.

Unless it is an entrance rated switch,(those are very expensive) it will require a amperage protective device prior to it, ie C. Breaker or fuses. This installs between your Power meter and said switch, you may already have one.

Install a utility power alarm, you can see or hear in the home, that is inactive when the switch is in the utility position. There are many ways to do this.

Good luck,


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## motorhead12 (May 1, 2013)

DPDT switches are not code where I live, because of possible power bleed back into the service cable. I'm not sure if that's local or not. However, there is something called an Interlock switch, which is code, and removes the need for a subpanel.


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## KRE (Nov 29, 2011)

DPDT manual transfer switches that are NEC and CE approved can be used everywhere. You can not use a std DPDT relay or switch w/o electrical and mechanical interlocks though. Automatic Transfer switches are nothing but motorized relays with E&M interlocks, an CPU's.

The old way of doing it was two circuit breakers with the left one mounted up side down and a slide bar between them. Both had to be off before you could turn the one unlocked via the bar, on. Used on ships to this day.


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## Apple206 (Jan 28, 2015)

thank you for the info.


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