Following on this question, I am in a similar situation, but with a few different details:
I currently have 125A utility electrical service to my house, feeding an outdoor Square D Homeline panel. The house was re-wired completely in ~2011, and there are no MWBCs that I am aware of.
I also have a 3750 running watt portable backup generator, with TT-30 receptacle.
My goal is to add a generator interlock to my panel, enabling me to feed 120V to both sides of the panel with a 30A double pole breaker and a generator inlet box.
Due to some nuances of my property lines, a carport, and the location of the panel, locating the generator close-ish to the panel while still allowing for good spacing from the house is surprisingly challenging. In a perfect world, I would install a new run of 10/3 through the crawlspace, ending at an appropriate location for a remote generator inlet.
Here's where things get interesting:
There happens to be a an already-installed run of 10/2 romex directly terminating at an old A/C disconnect box (the A/C was relocated ~10y ago). This old A/C box would make for a perfect generator inlet location.
I'm hoping I can repurpose this existing 10/2 line for my generator inlet rather than pulling a fresh run of 10/3. It would be substantially more convenient to re-use this line vs. embarking on a new wiring job in the crawlspace.
I'm wondering if the following is feasible, code compliant, and safe:
- Replace the old, unused A/C disconnect box with a 3-prong generator inlet box (e.g. a Reliance PB-31, with an L5-30 connector)
- Wire the generator inlet to the existing 10/2 line running to the panel
- Inside the panel, jump the the hot conductor of the existing 10/2 line into both poles of a 30A double-pole breaker by way of a wire nut (hot from the 10/2 IN, two short 10GA wires OUT to the two poles of the breaker)
- Install the appropriate, OEM, Square D interlock kit on the 30A generator breaker, ensuring that backfeeding is not possible.
- Connect the generator to the inlet by way of a TT30 extension cord and an adapter to match the connector on the inlet
- When the backup generator is in use, keep all actual 240V circuits turned off. Only run the minimum required set of 120V circuits
I'm looking for some feedback on #3 above. My reference point for this idea is that I have seen many generator extension cords that adapt a 3-prong connector (like a TT-30) to a 4-prong (like an L15-30) by jumping the X and Y poles at the 4-prong plug. So...can this same jump be safely accomplished inside the panel itself?