Spa / Sub-panel Suggestion


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Old 05-22-15, 10:59 AM
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Spa / Sub-panel Suggestion

Hello! Looking for any better suggestions on the following situation if one exists.

Our house used to have a hot tub in the back, which is all concrete hardscape now. The previous owners ran a 3-wire (#8, or possible #6) 220v circuit from the main panel, in conduit underground, to the ideal location. It's about a 75ft run, down from the main panel, straight along the side walkway under all that concrete, and right up onto the wall in the back of the yard where the tub used to be. There is also a 50amp GFCI breaker in the main panel protecting this curcuit.

I want to by a new tub from CalSpa, but the electricial requirements state the following:

50amp GFCI protected dedicated circuit
4-wire, #6

From all my research I believe my only option is to pull new 4-wire through the exisiting conduit to meet the spa requirement. I'm assuming there might be some 120v stuff in the spa in addition to the 220v, hence the need for 4-wire?

Also, I'd also like to add an additional 120v circuit in the same area, and that existing conduit is really the only viable path without ripping out concrete. So my complete idea was this....

Pull new 4-wire, #6 copper cable through the conduit:

Southwire 125 ft. Black 6-3 Romex NM-B W/G Wire-63950002 - The Home Depot

Add a new 60amp breaker to the main panel to feed it.
Install a SUB-PANEL on the other end near the spa.
Move the 50amp GFCI breaker to the sub-panel for the dedicated spa circuit.
Add a 15amp breaker for a new 120v circuit in the back yard.

Any better advice on this? Ideally I wanted to feed the sub-panel with a larger breaker, but I don't think it's feasible to pull any larger cable, and I also don't seem to be able to find any larger, 4-wire copper cable at home depot.

Thanks!
 
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Old 05-22-15, 11:17 AM
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That cable cannot be used outside, even in conduit. Also the feeder to a panel for a pool or spa needs an insulated ground. NM cable has a bare ground.

What size conduit is there and what is it made of?

Individual conductors are used in conduit.
 
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Old 05-22-15, 11:42 AM
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Thanks for this. I'll have to look more closely at the conduit to determine size. Pretty sure it's PVC.

The existing 3 conductors pulled through the conduit fill most of the space, but I think there should be enough room for a 4th. The existing 3 are all insulated, I think #8 or #6 for the hots and a size smaller for the ground.

If I need to pull individual conductors, and wanted to do an 80amp breaker, would I be looking at something like this?

http://www.homedepot.com/p/Southwire...9099/204632882

#4 for the hots/neutral, #6 for the ground?

Also, assuming the new conductors will fit, any tips for using the existing conductors to pull the new conductors through the same conduit? Again, it's a long run, around 75ft underground.
 
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Old 05-22-15, 11:59 AM
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If you wanted to do 80A or 90A, you need #4 hots & neutral + #8 green ground. This would require PVC conduit 1" or larger.

If you only have 3/4" conduit, the max that will fit is #6 hots & neutral, #10 green ground which you can protect with a 70A breaker.

In either case, the conductors should be THHN/THWN-2 copper. The hots should be black, neutral white and green ground. The only exception is if the neutral is #4 or larger you can use white tape to re-mark a black wire.

Old underground conduits are often filled with gunk. I would use the existing wires (if they will move) to pull through a rope. Use the rope to pull through a rag a couple times to swab the pipe. Then pull in the new wires. If the old wires are stuck, you may need to use some water and an air compressor to try to break it loose.
 
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Old 05-22-15, 12:06 PM
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Excellent advice!

What's the process for using water and an air compressor to break loose existing wires?
 
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Old 05-22-15, 12:15 PM
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Many hot tub instructions call for a full size ground which is over and above the NEC requirements.
 
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Old 05-22-15, 12:20 PM
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Would this be from the SPA to the SUB-PANEL only, or would I need full size ground from the SUB-PANEL to MAIN-PANEL as well?

Also, do panel neutral/ground bars usually accommodate #4 wire sizes?
 
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Old 05-22-15, 12:21 PM
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The process is filthy is what it is. Put some water in the conduit and try to blow it through with a compressor and blow gun. Crap flies everywhere, mostly in your eyes so wear glasses. Hopefully the old wires will pull out without too much trouble.

If they are really badly stuck, there is a chemical that will dissolve the insulation to loosen the jam but it is nasty to work with. The other possiblity would be the conduit has collapsed, but let's hope you won't have that problem.

Good point pcboss, the tub might require the full sized #6 ground all the way back to the main.
 
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Old 05-22-15, 12:24 PM
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A neutral bar will normally accept up to a #4 without needing an adapter.

IMO just from the last panel to the spa. The other portion is under the NEC, not the spa instructions. I disagree with needing the full size, but the instructions must be followed.
 
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Old 05-22-15, 12:31 PM
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Any particular rope to use to pull cable of this size through conduit?
 
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Old 05-22-15, 12:34 PM
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A poly pull line is cheap and sufficient. Also lube up the wires with pulling lube as they go in the pipe. [ATTACH=CONFIG]50912[/ATTACH]
 
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Old 05-26-15, 11:05 AM
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Confirmed that the existing conduit is 3/4" PVC. Just confirming the max I can run is #6 hots, neutral and ground with a 70amp breaker?

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Old 06-01-15, 03:39 PM
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Yes the max you can run in that pipe is a #6 feeder, and that will be a snug fit. You will need a lot of wire lube and a helper on each end of the pipe to complete this job successfully without damaging wires or getting the pull jammed.
 
 

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