Running Cable for new Hot Tub Question

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Old 05-01-19, 12:57 PM
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Running Cable for new Hot Tub Question

Good afternoon,

I purchased a new hot tub this past weekend and it should be delivered next week. I wired my old hot tub, which was only 40amp service with cable I had laying around the house. I need to strip that cable out and add in 50amp cable with a shielded ground(green) to be in compliance. My questions are below:

- My hot tub manual says to use 8awg for my cables, but I already know that's not right, cause 8awg is not rated for 50amps. So I plan to use 6awg.

- I've shopped around for wire and most big box stores have 6/3, and then I would need to buy a single conductor wire wrapped in green for my ground.

- I have found RV plugs to be 6/4, all insulated conductors, and rated for 50amps. They are also rated waterproof applications.

- Is there any harm to buying 30 feet of RV cable and just cutting plug off the end? These cables are commonly used for RV's and generator wiring into a house. I don't see why this would be an issue for a hot tub. The cable is 6/3 and 8/1, which is no different than buying a 6/3 and a single strand of green.

- The cable will be run through conduit.

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Last edited by PJmax; 05-01-19 at 02:34 PM. Reason: resized pictures
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Old 05-01-19, 02:30 PM
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The correct method is to run individual conductors in conduit outside. You may use cable with bare ground inside but must transition to conduit and insulated ground outside. You can not use service cable.
 
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Old 05-01-19, 02:34 PM
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So I don't plan to use individual conductors, I was looking to use this cable for an RV. Is that what you're calling a service cable? If so, why couldn't I just strip the individual conductors out of this RV cable and it would essentially be the same thing as if I were to buy them individually. I was planning to use this shielded cable pictured from my main panel to outside sub-panel, then into the hot tub box. All outside work will be through conduit.
 
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Old 05-01-19, 02:36 PM
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That is rated as extension cord duty. It cannot be pulled thru conduit.
Thru conduit you must use THWN/THHN conductors.

Can we assume this is an outdoor spa ?
You are required to have a disconnect within site of the spa and no closer than I believe 6'.
The ground wire needs to be insulated only outside.
 
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Old 05-01-19, 02:39 PM
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The plan I set forth was the following:
- 12 feet of cable from my main home panel to a subpanel outdoors. about 8 feet is indoors, the other 6 feet would enter conduit outside into the sub.
- Wire up the sub.
- 5-6 feet to the hot tub.

Yes, it's outdoors. And if I understand correctly, most RV 50amp cables are made with THWN/THHN conductors to comply with code.
 
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Old 05-01-19, 02:52 PM
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The type of the cable should be right on it. Probably stamped into the black jacket.
That looks like a type of SJ or SJOO cable,
 
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Old 05-01-19, 02:56 PM
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The cut section is SOOW, but I was just using that as an example. The upper picture is the actual product I'm buying. When it gets here, I'll check out what the shield says. So if the cable is THHN, can I run it wrapped to the wall, then strip it to individual shielded conductors when I get to my conduit and run as individuals from there to my box?
 
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Old 05-01-19, 03:03 PM
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You upper picture is service (portable) cord and can not be used. There are several type either sold naked or made up sch as as a cord set. None of the varieties can be used. https://en.wikipedia.org/wiki/Portable_cord
 
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Old 05-01-19, 03:20 PM
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I will check the conductors when they arrive tomrrow in that service cable. The conductors on my 30 amp RV plug I currently have are THHN. If this new cable comes in as THHN conductors, then I would imagine I could just strip the outer jacket off and use that. Otherwise, it looks like I may be off to lowes for a by the foot individual conductor order and some conduit.
 
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Old 05-01-19, 03:45 PM
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THHN can not be used outside even in conduit. You need THWN.
 
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Old 05-01-19, 03:53 PM
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Isn't THHN just THWN with a higher rating for degrees in dry and wet applications? I also thought most new THHN cable today was dual rated as THHN/THWN-2?

I should clarify that I know THHN is not rated for water. But It was my understanding that most placed that sell THHN by the foot, the shielding is marked as THHN/THWN-2 which allows you to bury it in conduit.
 
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Old 05-01-19, 04:20 PM
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But It was my understanding that most placed that sell THHN by the foot, the shielding is marked as THHN/THWN-2 which allows you to bury it in conduit.
Yes.... that is correct but the service cord you are waiting for will not be stamped for both.

The THHN/THWN that is purchased off of a roll has a clear thermoplastic covering on it that makes it waterproof. Service cords don't come with that.
 
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Old 05-01-19, 04:49 PM
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It's not just the insulation of the cord or cable that is the issue, although that's important.
110.14 of the National Electrical Code requires that the terminals on equipment must be identified that they are suitable for wire with finer stranding than class B or class C wire before such finer wire can be used. Class B has 7 strands and class C (most common in building wire) has 19 strands for all wire gauges #2 through #20. I doubt that any panels, breakers, devices, etc. in common use for residential applications would be approved for finer wire such as that in flexible cords. Except, of course, plugs and receptacles specifically designed to attach to flexible cords.
 
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