I purchased a 50amp (10 circuit) manual transfer switch. I plan to connect it to a 12,000 watt (240v/120v) generator via a 50amp inlet box mounted to the exterior of the house with #6/3 w/gnd. running between the transfer switch and the inlet box. Now, knowing that the 4 prong outlet on the generator gives me 2 hots, 1 neutral, and 1 ground, doesn't the inlet box also need to be a 50amp 4 prong device, as well as the extension cable running between the inlet box and generator having 4 prong connectors on each end? I can find 30amp 4 prong inlet boxes, but I only seem to be able to find 50amp 3 prong inlet boxes. I appreciate any help I can get. Thanks.

  • 2
    I strongly recommend avoiding those transfer switches if a generator interlock is made for your panel. The transfer switches cannot be used on circuits with GFCI or AFCI breakers. Nor with shared neutrals (unless both are placed on a 240V breaker in the xfer switch). Interlocks don't have these problems, let you energize any circuit in the panel, and are 1/4 the price lol. Unused transfer switches sell well on Craigslist/Facebook marketplace. Nov 3, 2021 at 17:32
  • Wow! Thanks for the Tip. Wish I had known about this option before I ordered the transfer switch, but at least I haven't installed it yet so I should be able to send it back. Thanks again!
    – Rob Spitz
    Nov 4, 2021 at 11:38

1 Answer 1


Enter "NEMA 14-50 inlet" (or "NEMA L14-50 inlet" for the twist-lock type that are less prone to vibrate loose) into your search or shopping site of choice.

  • Hey, that worked! Thanks a bunch!
    – Rob Spitz
    Nov 3, 2021 at 15:17
  • BTW: there are no L14-50 inlets -- it's a CS6375 instead Nov 3, 2021 at 23:52

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