My question is very similar to this one (Can I plug a 120 volt generator into a 240 transfer switch with a modified cord/connector?), but I'd like to know whether DDS's answer is code-legal under the 2014 NEC.

To make sure it's clear what I'm asking about, I'd like to use a 120V portable generator to feed a 120/240V panel. There are no 240V loads, so I would like to simply install an interlock between the main breaker and the backfeed breaker to avoid installing an entire transfer switch panel. The loads throughout the building are within range for the generator, so I'm not worried about overloading it, but I would like for both busbars in the panel to receive power. I would use a 2-pole breaker, but both screw terminals would connect to the same wire from the generator.

Is this code-legal?

  • Is there a service connected to this panel already? Dec 3, 2018 at 2:40
  • @ThreePhaseEel Yes. I would be using an interlock plate to prevent islanding
    – Hari
    Dec 3, 2018 at 4:26
  • Is having the meter pulled for the duration an option? Dec 3, 2018 at 5:09
  • They do make interlock kits that lock out your main breaker and allow a backfed breaker to be used. But tying both busses together I would just move the needed loads to the same leg ie all odd or all even.
    – Ed Beal
    Dec 3, 2018 at 16:46
  • 1
    As long as it is interlocked it should not be a problem because it would be isolated. Moving loads would be safer, I always have a couple of inches extra wire so I can balance the service but some cut very short, I would try, just the idea of something going wrong is scary.
    – Ed Beal
    Dec 4, 2018 at 13:17


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