NM-B under house for hot tub installation

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Freshta

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So, the hot tub sales people and I were discussing wiring one of their spas and they say that 6/3 NM-B CU cannot be used for a 50 amp spa circuit from the panel (indoor-garage) to the disconnect (located on side corner of house). From the disconnect to the spa I'm running #6 THWN-2 through 1" PVC. 6/3 NM-B is rated for 50 amps and is under the house and terminating at the disconnect. Am I missing something?

Thanks,

Tony
 
Freshta said:
So, the hot tub sales people and I were discussing wiring one of their spas and they say that 6/3 NM-B CU cannot be used for a 50 amp spa circuit from the panel (indoor-garage) to the disconnect (located on side corner of house). From the disconnect to the spa I'm running #6 THWN-2 through 1" PVC. 6/3 NM-B is rated for 50 amps and is under the house and terminating at the disconnect. Am I missing something?

Thanks,

Tony
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Sounds good to me.

I would tell the sales people that you are getting the job permitted and inspected and it will pass local and NEC codes and if they want anything more it will cost extra.

If you have any doubts then call the local inspection department they may see things different.
 
what is meant by the title of this thread, "under house" ??

i think there might be some gray area with 680.21, in general the code sections around bodies of water. a insulated EGC is mentioned many times. i have seen where some have said that insulated EGC would carry all the way back to the panel, so instead of NM-B it was UF-B inside.

what version of NEC does your locale use ??

Branch Circuit Wiring
If installing raceway on buildings, you can use electrical metallic tubing. Within buildings, you can use electrical nonmetallic tubing, Type MC cable, electrical metallic tubing, or Type AC cable. These must contain an insulated equipment grounding conductor sized per 250.122 but no smaller than 12 AWG [680.23(F)(1)].
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however, this quote might be in context of "on buildings" and specifically related to the type of allowed wiring being mounted to the building on the inside walls/ceilings where the pool stuff is inside the building. not 100% sure.


the insulated EGC is for a reason, and from my view it should carry all the way back to the panel, UF-B should suffice to meet that requirement for the wiring inside the home, etc.
 
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Freshta said:
So, the hot tub sales people and I were discussing wiring one of their spas and they say that 6/3 NM-B CU cannot be used for a 50 amp spa circuit from the panel (indoor-garage) to the disconnect (located on side corner of house). From the disconnect to the spa I'm running #6 THWN-2 through 1" PVC. 6/3 NM-B is rated for 50 amps and is under the house and terminating at the disconnect. Am I missing something?

Thanks,

Tony
Click to expand...
The manufacturer may require a full size equipment ground. (and-or) that it be insulated.
 
I also have seen a few tubs that call for a full sized equipment grounding conductor. This is why we just pipe it all the way and our butts are covered
 
Freshta said:
So, the hot tub sales people and I were discussing wiring one of their spas and they say that 6/3 NM-B CU cannot be used for a 50 amp spa circuit from the panel (indoor-garage) to the disconnect (located on side corner of house). From the disconnect to the spa I'm running #6 THWN-2 through 1" PVC. 6/3 NM-B is rated for 50 amps and is under the house and terminating at the disconnect. Am I missing something?

Thanks,

Tony
Click to expand...

Full size or insulated ground may be required as already mentioned. Also, if the FLA are 43-48, you would need a 60A circuit and #6 NM is undersized for that.
 
JFletcher said:
Full size or insulated ground may be required as already mentioned. Also, if the FLA are 43-48, you would need a 60A circuit and #6 NM is undersized for that.
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The manufacturer says it is a 50 amp spa... I know they probably make them but I have never seen a hot tub over 50 amp
 
In KY, the inspector allowed us to use 6-3 CU Romex from panel to outside disconnect and gfi CB.
Then individual conductors in conduit from there. In IN, they don't allow any UF for pools, because it does not have an insulated ground, only a jacketed one. Each city/state is different, I always have to call and ask.
 
This section is about branch circuits to motors. For a single family dwelling you can run nm to a jb on the exterior but from there the wiring must have an insulated ground-- very similar to a hot tub

680.21(4) One-Family Dwellings. In the interior of dwellingunits, or in the interior of accessory buildings associated
with a dwelling unit, any of the wiring methods recognized
in Chapter 3 of this Code that comply with the provisions
of this section shall be permitted. Where run in a cable
assembly, the equipment grounding conductor shall be permitted
to be uninsulated, but it shall be enclosed within the
outer sheath of the cable assembly.
Click to expand...
 
I've hooked up a couple of 50A spas recently that required #4 conductors per the nameplate at the terminals in the spa.


Sent from my iPhone using Tapatalk
 
Dennis Alwon said:
The manufacturer says it is a 50 amp spa... I know they probably make them but I have never seen a hot tub over 50 amp
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Some mfg specs just show either 40A or 50A, but you have to dig a little and see they are just listing the FLA and you need to figure in the 125%.

40A x 125% = 50A
50A x 125% = 60A

Usually the 60A tubs have two pump motors and are sized to run the heater at the same time as both pumps. I've seen specs say you can wire them at 50A or 60A but can't run both pumps and heater at the same time if you choose 50A.
 
Dennis Alwon said:
This section is about branch circuits to motors. For a single family dwelling you can run nm to a jb on the exterior but from there the wiring must have an insulated ground-- very similar to a hot tub
Click to expand...

680.21(4) One-Family Dwellings. In the interior of dwellingunits, or in the interior of accessory buildings associated
with a dwelling unit, any of the wiring methods recognized
in Chapter 3 of this Code that comply with the provisions
of this section shall be permitted. Where run in a cable
assembly, the equipment grounding conductor shall be permitted
to be uninsulated, but it shall be enclosed within the
outer sheath of the cable assembly.
Click to expand...
what NEC version is this quote?
isnt that the catch, doesnt it basically say only the wiring methods mentioned/allowed in 680 ?
 
FionaZuppa said:
what NEC version is this quote?
isnt that the catch, doesnt it basically say only the wiring methods mentioned/allowed in 680 ?
Click to expand...


That is the 2014 but it hasn't changed in years. Look at the part below that mention cable assembly

Where run in a cable
assembly, the equipment grounding conductor shall be permitted
to be uninsulated, but it shall be enclosed within the
outer sheath of the cable assembly.
Click to expand...
 
Dennis Alwon said:
That is the 2014 but it hasn't changed in years. Look at the part below that mention cable assembly
Click to expand...

yes, i know. but that whole blurb is in context "...that comply with the provisions of this section..." , does NM comply with any part of 680?
 
FionaZuppa said:
yes, i know. but that whole blurb is in context "...that comply with the provisions of this section..." , does NM comply with any part of 680?
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Not any part, specifically section 680.21.

Remember, 680 is an article, a section is only part of an article and yes NM complies with that section.
 
iwire said:
Not any part, specifically section 680.21.

Remember, 680 is an article, a section is only part of an article and yes NM complies with that section.
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yeah..... i know......
2008 nec 680.21(a)(4)
does allow NM inside the sf-dwelling

but why does nec say insul-gnd if in a raceway, no required insul-gnd if in a cable? bare copper in pvc, any different than bare copper in NM (other than the paper wrap)?
 
FionaZuppa said:
yeah..... i know......
2008 nec 680.21(a)(4)
does allow NM inside the sf-dwelling

but why does nec say insul-gnd if in a raceway, no required insul-gnd if in a cable? bare copper in pvc, any different than bare copper in NM (other than the paper wrap)?
Click to expand...

If I had to guess it is because no one has put in a proposal to allow it laying out the hardship created by using a insulated EGC in PVC. ;)
 
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