spa hot tub hookup with 6/3 nm-b wire

[Electricalguy]

Is there anything in the code for or against using 6/3 nm-b wire in liquid tite for a hot tub. this would be from a 50 amp 240 volt gfci breaker disconnect on exterior of house then in the ground 18 inches deep for 20 feet then in to the hot tub to the electrical connections for the tub. I can't find anything for or against it. could anyone reference specific codes saying if its ok or not.

 

[Coppersmith]

Yes. NM is not allowed where it will get wet. Conduit that is outdoors or underground is a wet location. You can use UF or THWN.

334.12 Uses Not Permitted.
(B) Types NM and NMS. Types NM and NMS cables shall not
be used under the following conditions or in the following
locations:
(4) In wet or damp locations

 

[LarryFine]

You can use UF or THWN.

I recommend the latter; you can use a much smaller conduit.

 

[rnatalie]

NM is not alllowed in wet locations.
Most pool/spa locations outside a house require a separately insulated ground (not just the cable sheath).

 

[brantmacga]

NM is not alllowed in wet locations.
Most pool/spa locations outside a house require a separately insulated ground (not just the cable sheath).

In the 2017 and 2020, the general requirements of chapter 3 apply to feeders in non-corrosive environments. In a corrosive environment, only that portion of the feeder requires an insulated grounding conductor. 680.25.

Branch circuit wiring requires an insulated grounding conductor.


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[jimport]

The interior portions of the wiring can have a bare EGC.

 

[rnatalie]

In the 2017 and 2020, the general requirements of chapter 3 apply to feeders in non-corrosive environments. In a corrosive environment, only that portion of the feeder requires an insulated grounding conductor. 680.25.

There were three versions of the requirement. The original required insulated ground elsewhere. Then only the outdoor section, now only in corrosive environements.

However, if you dig down to what they consider a corrosive environment is, it equates to anything near the pool anyhow.