Wiring a SPA

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  #1  
Old 09-10-01, 07:30 AM
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I need to run a circuit to a SPA, which is to be installed on a deck. The SPA requires a 240V 50amp circuit. My plan is to run 6-3 w/Ground NM from a 50amp 2-pole breaker in the main panel. This wire will drop out of the panel, go through a hole in the rim joist just below the panel, travel approximately 15' along a floor joist, exit another hole through a rim joist and vinyl siding, where it will be enclosed in plastic electrical conduit, beginning under the house, until it enters a subpanel mounted on the exterior wall (over the deck). The subpanel will contain a 50amp (SquareD QO) GFCI breaker. From there it will travel, again in conduit, to the SPA - making sure that the distance is at least 5 feet from the GFCI to the load in order to minimize false trips.

Any problems, suggestions? I want to get this right, and inspected!
 
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Old 09-10-01, 02:28 PM
Wgoodrich
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The wire size seems good, the NM cable may be good may not. The NM cable that I am jumping to conclusion that you plan to use is type NMB cable that is used normally inside a dwelling. You need to check with your AHJ for an approval in your design. Technically the NMB cable is approved for a dry location only. [Romex] However you are running this cable outside but in a conduit. The AHJ makes the final call whether this cable can be used in a conduit outside or not. Good chance you will need to change to THWN wire in that outside conduit. See what he says on that one.

The disconnect serving that spa is required to be within sight. That disconnect is also required to be a minimum of 5' away from that spa.

All else should pass Code.

Now a couple of suggestions and a point of knowledge.

You could place your GFI breaker in the main house panel and install the disconnect as a non fused disconnect. This should save you about 1/3 the cost. The disconnect is not required to be with an overcurrent device.

Also a GFCI is not required to serve a spa. It would give you some extra protection but that GFI is not required to meet you inspection approval meeting minimum Code requirements.

Hope this helps

Wg
 
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Old 09-11-01, 12:31 AM
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Thanks! It helps a great deal. This is just the sort of info I was looking for. I will definitely check with the codes people about the GFCI and NMB. Doesn't THWN come in single conductor only? If so, wouldn't I have to run it in conduit all the way? No problem in the case, the run is pretty simple.

Again, thanks!
 
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Old 09-11-01, 01:26 AM
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Check the instructions for your particular spa, the ones I am looking at (Hot Springs) specify precisely the wiring required (i.e., number of conductors, gauges, etc). They specifically forbid Romex.
 
  #5  
Old 09-11-01, 01:31 AM
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More good info. Believe me, I have abandoned the romex idea! THWN it is.

Thanks,
 
  #6  
Old 09-11-01, 11:25 AM
Wgoodrich
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I am not aware of the instructions by the manufacturer that mikewu99 is talking about. I supect that the NM cable being forbidden may be just in contact with the spa. Check you manufacturer's recommendations that came with your spa. If the instructions do not forbid NM use or if the NM is forbidden only to be in contact with the spa itself then you can solve your wet location problem and still use your NMB cable inside your dwelling. You could possibly run your NMB cable from the panel to a junction box just inside the outside wall of the dwelling then switch to conduit and type THWN single conductor wire approved for a wet location limiting your conduit installation to outside only. Be sure to use a weatherproof disconnect whether you use a fused or nonfused disconnect. Remember that the disconnect form must be at least 5' from the spa but in sight of that spa which would limit the maximum distance to 50'.

Good Luck

Wg
 
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Old 09-11-01, 01:02 PM
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Actually I believe that the prohibition against Romex has to do with an oversized ground conductor which they specify (larger than what would be found in Romex appropriately sized for the current-carrying conductors). I'll see if I can find the instructions to verify.
 
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Old 09-12-01, 12:24 AM
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Thanks gentlemen, I certainly have enough good info here to stay out of trouble, and to at least ask the right questions of the codes people. Mikewu99, I did see, at least on one spa site, a requirement to (I think I have this right) to provide a ground wire at as large as the current carrying conductors with a certain minimum size - #10, I believe. That is probably where the romex problem comes in. I can see a lot of room here for local codes interpretation, so I'm definitely going to check with them and the spa retailer first. As I said, now I will be able to ask the correct questions and perhaps not come across as a complete dummy. In my county, they don't seem to mind DIY electrical work as long as you seem to know what you are doing. They ask lots of questions when you apply for the permit and they look your work over closely.

Thanks again guys,
 
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