Generator Interlocks


Old 10-14-13, 12:43 PM
Thread Starter
Join Date: Oct 2013
Location: USA
Posts: 2
Generator Interlocks

The info below is very good, I just add as a master electrician, you should get an interlock kit that has been tested by a NRTL (fancy talk for a Nationally Recognized Testing Lab) like UL or MET Labs or Wyle Labs or CSA. Some electrical inspectors require this but we have had to go back and show home inspectors (owners selling the house) that we used a NRTL tested kit. OEM kits have the original UL and kits from have published test reports. Just be careful not to use some off brand to save a few bucks.


Last edited by ray2047; 10-15-13 at 06:33 AM.
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Old 10-14-13, 03:11 PM
Join Date: Oct 2013
Posts: 2
After much research I just installed an interlock this weekend.
I consulted a friend who is a licensed electrician and he recommended the interlock over a transfer switch.
Both an interlock and a transfer switch prevent backfeed if installed correctly.
Always get a permit and an inspection for electrical work!
Interlock pros:
-slightly less expensive (i s$200 before permit)
-minimal wiring - one wire and one circuit breaker
-not limited to 6 or 8 circuits as long as you are not overloading the generator you can use any circuit in the house
-power inlet on exterior of the building - manual switch with built in inlet means you are running an extension cord through an open window or door.
Interlock cons:
- no load balancing - you have to do that within the panel and in your head
- you can easily overload the generator if you turn on too many breakers
- removing the panel cover containing the interlock disables it and can allow backfeeding

I decided my wife and I are capable of choosing circuits to suit the circumstances without overloading the generator. If we do, it is our own fault.
I also moved circuit breakers around in the panel to make sure my two sump pumps were on different legs etc.
Finally i created a diagram of breakers that could be used in conjunction without overloading the system or create unbalanced loads.
Old 10-15-13, 06:23 AM
Thread Starter
Join Date: Oct 2013
Location: USA
Posts: 2
Connecting Portable Generators to Home Panel

Sounds like you have a pretty good handle on how to use the portable generator. On the question of overloading the generator, they do have breakers on them to protect the generator. We generally use the interlocks from but I would love to know if anybody out there has found a simple and cheap amp meter that can be mounted on the generator to help balance the load.

Old 10-15-13, 09:18 AM
Join Date: Sep 2013
Posts: 85
The $129 Currentcost EnviR can give you watt readings at your desk. The clamps would go on each leg going to your generator breaker in the panel. You can get 2 more sensor clamps/transmitters to monitor your utility watts, kilowatt hours and utility cost. The remote meter can take up to 10 channels.

There are several software options to read channels on the internet. You would need a bridge or USB serial cable. I use the energy dashboard.


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