Hot Tub Ground Question

[Musky]

Question from main panel to spa panel.

Since romex can't be run outside, I would like to run UF-B cable from my breaker panel to the spa ground fault panel through my attic. The spa panel will be on my Exterior brick wall and short vertical conduit from spa panel will be stubed up in the attic. UF-B has a uninsulated ground. I understand an insulated green ground is required but Is the requirement for an insulated ground only from the spa panel to the hot tub?

I would also like to run the UF-B in conduit from Spa Panel to Spa but I understand that is not allowed. Did i read the code wrong?

 

[wwhitney]

Let's see, looks like OH uses the 2023 NEC per up.codes. I'm not super familiar with Article 680 on pools and spas but 2023 NEC 680.7(A) says "Feeders and branch circuits installed in a corrosive environment or wet location shall contain an EGC that is an insulated copper conductor sized in accordance with Table 250.122, but not smaller than 12 AWG."

So you can use UF-B in your attic, but not outside the house, as that would be a wet location. You'd need to install a junction box where the feeder or branch circuit emerges from the house and switch over to a wiring method with an insulated EGC. No UF in the "short vertical conduit from span panel (that) will be stubbed up in the attic."

UF is a bear to pull through PVC anyway, so using individual conductors in PVC is a better idea.

Cheers, Wayne

 

[Sponsor]

 

[Musky]

Thanks

 

[Musky]

Nothing is ordered yet but this is my current plan. I am trying to avoid splices in the attic.

I need 75' of 6/3 from breaker box to hot side of spa panel with the last 6' in conduit stubbed up in the attic. So i will carefully remove the outer jacket to expose the three 6 gage THHN insulated wires and the bare #10 gound. I will remove about 10' of the bare ground and splice it in the attic. I will attach a #10 insulated ground to the tag end of the bare ground in the attic and secure the splice in a plastic box.

Should the 6' conduit be metal or Sch 40 PVC?

Should the conduit be 3/4" or 1"?

I believe this will be in compliance.

Thank you in advance

 

[wwhitney]

Does the spa require 120/240V (3 circuit conductors) or is it 240V only (2 circuit conductors)?

If it is 240V only, then you can use any suitable (wet location rated) 6/3 cable and simply reidentify one of the non-white insulated conductors using green tape at each location where the cable jacket is stripped, per 2023 NEC 250.119(C).

If it is 120/240V, so you require 3 circuit conductors, you could do the same with a 6/4 cable, but that is a less common thing to find.

If you use PVC jacketed (wet location) 6/3 MC cable, then it has an insulated green conductor inside as well, so it would work for the whole run. I believe PVC jacketed MC used a specific connector type at each end to maintain watertightness. Still, your cable run into the spa panel would need to run down past the top of the panel and enter the lower side or the bottom. That does save you the trouble of using a hub on the top of your spa panel. You could still cover your MC cable with something like an A/C line set cover, or you could sleeve most it in conduit, just leaving the connector exposed.

As to your proposal, stripping the jacket from 10' of NM cable to run in conduit outside is a no go, as there is no guarantee that the conductor insulation is wet location rated (although it may well be, it is unmarked). As to doing the same with UF cable, that would be fine if the conductors inside have their conductor type marked on them. I'm not sure if they do, they may be like NM in that regard. If not, one could argue that it's not allowed to run them as individual conductors in conduit, although they are clearly wet location rated, so that is at most a technical labeling violation.

If you splice your wiring method in the attic, the size of box you require is the same whether the 3 ungrounded conductors run straight through unspliced, or you splice them in addition to your EGC.

For sizing your conduit, see NEC Annex C. If the spa panel enclosure is metal, using either PVC, EMT, IMC, RMC would be fine. If it is nonmetallic, stick with PVC.

Cheers, Wayne

 

[Musky]

thank you Wayne, especially for you insite that I need THWN not THHN and it needs to be marked, not assumed. Looks more like I might be splicing in the attic.

I wonder if it is published if UF-B cable used THWN and if published counts for "marked", but would still have the bare ground issue.

 

[wwhitney]

thank you Wayne, especially for you insite that I need THWN not THHN and it needs to be marked, not assumed. Looks more like I might be splicing in the attic.

Depending on how complicated the attic run is, and how many degrees of bend would be required, you could run smurf tube (ENT) in the attic and conduit outside, and then just pull in THWN-2 conductors for the whole run unspliced.

Cheers, Wayne