NM-B vs. THHN question

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  #1  
Old 10-06-05, 09:37 AM
ctcjason
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NM-B vs. THHN question

Ok here is the deal, I didn't know where the best place to post was.....

I am confused and very frustrated….. I am buying an 05 Bahia 50amp spa. I talked with the electrician and he said use 6-3 nm-b wire inside and 6-3 UF outside for the tub. I told the electrician I would purchase all the wire and run it myself to save money so I ran 75ft of NM-B inside and then on the outside I have about 25FT of UF in 1.5” conduit. For me that doesn’t know any better it looks good and seems like it should work just fine.

I started reading other boards and some say NO WAY on the NM-B and UF and to only do THHN and then you have others like the electrician and saying on that is fine…. What are your thoughts on it. I read the manual for the tub and it is “recommended” to use THHN but also stated as long as it not aluminum and is up to code it is fine….. So I am confused on is it “ok’ to do that and recommended to use the THHN or is it a must to use the THHN???

Please Help!!!!


Thanks So Much

Jason
 
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  #2  
Old 10-06-05, 09:45 AM
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Code requires an insulated ground from the subpanel, and neither NM-B nor UF-B has an insulated ground. Call your inspector and check. And let us know what he/she says.
 
  #3  
Old 10-06-05, 09:48 AM
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Sorry, you were misinformed. the wire outside MUST be individual conductors. You are not allowed to use something with a bare ground wire outside. The 6/3 has a bare ground wire, so is not allowed. You can use the 6/3 NM inside (or even UF inside), but you must transition to individual conductors outside. Code in the US requires this.

there are many other code issues for tubs, spas, and pools. Make sure you get them all or you won;t pass inspection. Best yet, talk to the inspector. they will usually tell you exactly what you need.

It must also be THWN, which means waterproof. usually THHN is dual rated THHN/THWN, but check to make sure.
 
  #4  
Old 10-06-05, 09:49 AM
ctcjason
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Originally Posted by John Nelson
Code requires an insulated ground from the subpanel, and neither NM-B nor UF-B has an insulated ground. Call your inspector and check. And let us know what he/she says.
Worse case scenairo could I pull a seperate 6-3 THHN for a ground? So I don't have to replace all the stuff I have already pulled... That was a pain?
 
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Old 10-06-05, 10:20 AM
ctcjason
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Originally Posted by racraft
Sorry, you were misinformed. the wire outside MUST be individual conductors. You are not allowed to use something with a bare ground wire outside. The 6/3 has a bare ground wire, so is not allowed. You can use the 6/3 NM inside (or even UF inside), but you must transition to individual conductors outside. Code in the US requires this.

there are many other code issues for tubs, spas, and pools. Make sure you get them all or you won;t pass inspection. Best yet, talk to the inspector. they will usually tell you exactly what you need.

It must also be THWN, which means waterproof. usually THHN is dual rated THHN/THWN, but check to make sure.
Ok now you have me thinking.... the UF I have has 3 wires plus ground... Black, White and Red with a small copper ground. For 220 what wires would they use? Wouldn't the black and red be the power and the white is the ground and that little un-insulated copper wire is not used? Am I not thinking right?

Thanks For Your time.

J
 
  #6  
Old 10-06-05, 10:27 AM
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You are not thinking right. The white wire is the neutral needed by the spa.
 
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Old 10-06-05, 10:43 AM
ctcjason
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Originally Posted by racraft
You are not thinking right. The white wire is the neutral needed by the spa.
Ok Thank You!

So when I go get my THHN / THWN wire what colors should I get?

Gren, Black, White, and Red?

Thanks

J
 
  #8  
Old 10-06-05, 11:36 AM
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Use green for the ground. Use white for the neutral. For the hot wires you can use just about any other color. They can even be the same color if you want. However, I would go with black and red.
 
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Old 10-06-05, 11:39 AM
ctcjason
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Originally Posted by racraft
Use green for the ground. Use white for the neutral. For the hot wires you can use just about any other color. They can even be the same color if you want. However, I would go with black and red.

Sorry the more I think the more questions I have.... 6-3 also for the ground?
 
  #10  
Old 10-06-05, 11:46 AM
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I don't have the info in front of me to verify this right now, but I believe that the ground can be 8 gage.
 
  #11  
Old 10-06-05, 12:46 PM
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ctcjason, I think you have a glitch in your terminology. When we say "6-3" or "6/3", we're talking about a multiconductor cable assembly. The "-3" or "/3" identifies how many wires in the assembly (the grounding wire is not counted--it is assumed). When you're talking about a single wire, just say #6.
 
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Old 10-06-05, 12:51 PM
ctcjason
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Originally Posted by John Nelson
ctcjason, I think you have a glitch in your terminology. When we say "6-3" or "6/3", we're talking about a multiconductor cable assembly. The "-3" or "/3" identifies how many wires in the assembly (the grounding wire is not counted--it is assumed). When you're talking about a single wire, just say #6.
You are right! I am new to this stuff . I think what I am going to end up doing is pulling my 6-3 UF (with ground) out and run the THHN 3 wires at #6 and then a #8 for ground. How does that sound?
 
  #13  
Old 10-06-05, 12:55 PM
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Use the 6/3 cable to pull the THWN wires. Use wire lubricant on the wires.
 
  #14  
Old 10-06-05, 02:02 PM
ctcjason
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Ok here is another dumb question. I was just talking to the tub installer and he said the tub I am getting is a three wire tub see pic of the wiring block... Click Here He said there is no neutral after the GFCI box. He said what connects to the tub is two hots and a ground. Errrr I am more confused now.
 
  #15  
Old 10-06-05, 02:07 PM
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Well then you don’t need a neutral. However, I would still run one, since you or someone else may change the tub in the future.
 
  #16  
Old 10-07-05, 11:15 PM
pendoreilleskie
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Unfortunately my builder pulled 8/2 from the main panel to the sub panel and I did not realize until the house was sheetrocked ... I went back and pulled the correct wire (got a permit and an inspection) and it passed code, but it was a pain in the butt not having neutral from the main panel to the sub-panel on the outside of the house;(
 
  #17  
Old 10-08-05, 07:40 AM
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Pen,

If your builder is pulling wire without being an Electrical Contractor then I would report this issue to the local building department as it sounds like this builder is not following the law. But again I am in VA and we have so many laws regarding that.

If the sub-panel is located within the same structure of the existing panel and your builder only pulled 8/2.....he needs to have someone explain to him the rules that apply to the NEC on sub-panels.

Now I wont get into attached and detached issues......because based on your post we will assume both panels are within the same structure...thus making his 8/2 install....wrong.....and should be made aware of it.
 
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