Planning for future outdoor wiring


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Old 07-20-14, 07:14 PM
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Planning for future outdoor wiring

I'm doing some backyard work putting in a concrete patio and rebuilding a deck. While I've got the deck torn down and no patio in yet, I'm contemplating putting in a run of wiring for a spa that won't be connected to the main breaker inside the house. I figure this will help reduce the cost of an install when I'm ready to move forward with the spa.

The distance from the main breaker to my future location is about 30 feet away; roughly 15 feet inside the house and then another 15 feet outside. The biggest spas that I've been looking at need a 70 amp gfci sub. Would #4 THHN be suitable for this(something like this http://www.wireandcabletogo.com/4-3C...-Ground.html)? My indoor run would be in my unfinished basement along the foundation, would this have to go in conduit or a raceway? Once I get outside the house would I run this in a service ell down in the ground to pvc conduit at 18" and then back up and terminate it in a junction box or something near my intended use? I would not connect the wire to the main breaker and just leave it coiled up inside safely away from the main where hopefully an electrician could connect everything at a future date.

The big thing I'm trying to do is get all the digging and trenching out of the way now while I've got easy access to the ground and put some wire in place. Once the deck is rebuilt and the concrete patio put in place, I figure this is going to be a much bigger job. Does that sound like a reasonable plan that would hopefully save me time and money in the future?

Thanks!

-Paul
 
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Old 07-20-14, 08:06 PM
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Spas and pools have some rather stringent requirements, among them requiring an insulated equipment grounding conductor. I see no problem in running the conduit now (complete conduit underground) but hold off on any wiring until such time as you actually put in the spa. To allow for any eventuality I would use 1-1/4 inch conduit, schedule 40 underground and schedule 80 where it comes above ground.

BTW, the link doesn't work for me.
 
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Old 07-20-14, 08:10 PM
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First off your link does not work. Not a big deal as we can work around it. Second, conduit is a raceway, but the answer is no, you should not need need to use conduit unless it is required in your area.

If you run NM cable inside the house you would be required to run #4 copper. If it is in conduit, you can use #6 for up to 70 amps.

All tubs I have ever wired do not need a circuit larger than 60 amp. You are going to need a disconnect on the outside of the house within sight of the tub. This disconnect is required to be no closer than 5' IIRC. Here is how I would do it:

Run your NM cable from the panel to the outside of the house into the back of the disconnect and terminate there.

Out of the disconnect run PVC down 18" in the ground and then back up to where the tub will sit. You will want the pipe to come up right along the side of the tub, but not blocking the access panel. Tape off the pipe to keep stuff from getting in.

At the panel leave enough cable to get anyplace in the panel. I would suggest keeping the cable out of the panel, just coil it up between the floor joists/trusses.

When the time comes all that needs to be done is to terminate the cable in the panel, add an LB on the end of the PVC pipe and run the rest of the raceway to the spa control box. Then pull the wire and terminate at the spa control and disconnect.

Note: You will also need a 120 volt GFCI protected receptacle that is no closer then 6' and no further then 10' from the tub.
 
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Old 07-21-14, 07:52 AM
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Considering that this is all planning for the future, I lean toward Furd's suggestion of just roughing in the conduit at this time. Why try to guess what the future wiring requirements will be if you haven't decided on a tub yet?
 
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Old 07-21-14, 11:21 AM
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Here's the link I was trying to post

#4-3 THHN-PVC Tray Cable with Ground | WireAndCableToGo.com

One reason I wanted to run the wire in the conduit now was that I was worried I wouldn't be able to pull the wire through the conduit(I'll probably have one bend in it), so I figured I'd just go with the heavier gauge wire and spend a little more knowing that it will be able to handle the higher load.
 
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Old 07-21-14, 12:11 PM
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Why? Overkill in my humble opinion. Just install (1") PVC conduit outside as previously suggested. You can then use THWN. No reason to use cable in PVC and it's harder to pull. In the house you can use NM-b. Wire size should be determined after purchase. Empty conduit allows that. You can probably get by with 1" but 1" future proofs it and will make it easier if you go with cable.
 
 

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