We're wiring a J-355 Jacuzzi Hot Tub and the instructions said to use 6-3 wire for a 60 amp installation. We purchased Romex 6-3 wire, type NM-B, from a local box store to run through the basement from the electrical panel to the GFCI panel mounted on the outside of the house. Is this an acceptable wire or should we have used a THHN or THWN wire?

  • NM wire is illegal for use outdoors or in wet locations. You can use THWN but that must be inside conduit. And stop buying from box stores. Find your local electrical supply, typically locally owned by a family/neighbor (unless it's Graybar), pay a skitch more for wire and a lot less for everything else, and also get GOOD advice. Commented Oct 6, 2017 at 19:21
  • Thank you. You are so right about buying from local hardware/electrical supply stores. We would not only have helped to keep the small stores open but would have gotten good advice from them. Commented Oct 6, 2017 at 22:01

2 Answers 2


to run through the basement from the electrical panel to the GFCI panel mounted on the outside of the house.

You actually are not saying you intend to run the NM outside. If you run it through your basement studs and joists and up a wall and penetrate the wall into the back of the GFCI Panel. Then you should be able to run the NM as outlined in NEC 334.15 and 334.17. However if the NM is to run on the exterior of the building then it must be enclosed in PVC, sealtite or carflex, or you need to use some other approved type of conduit or cable installation (UF) as stated in other comments and answers.

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    Exterior conduit is defined as a wet location so no nmb in conduit outside. The reason is the paper can wick water into the enclosure I could not believe how much it can pump.. But to the box it would be ok.
    – Ed Beal
    Commented Oct 6, 2017 at 20:46
  • Thank you for your help. I think with all the great answers we got that we have this part of the installation figured out. Commented Oct 6, 2017 at 22:03

I don't believe 6/3 is available in solid. Everything I've seen is stranded.

The main thing you'll need to be sure of is using UF instead of NM wire for this. That's the only quality difference I know of here.

  • Is UF a requirement for hot tubs even if installed indoors? Just curious if this is because it's a tub vs. because it's probably outside and the wire will likely be buried. Commented Oct 6, 2017 at 17:32
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    Thank you. The NM wiring is only used inside ran overhead through the basement from the house service entrance to the GFCI box mounted on the outside wall. We will run conduit with 6 gauge wire from the GFCI box to the hot tub. Is this oK? Commented Oct 6, 2017 at 17:51
  • @ShimonRura Good point. The vast majority of hot tubs are mounted outside. If this is indoors, could probably get away with NM
    – Machavity
    Commented Oct 6, 2017 at 18:03
  • @HoneyDoList That should be fine. I would suggest conduit as well, but it's not required
    – Machavity
    Commented Oct 6, 2017 at 18:04

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