Hot tub wiring question

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Old 10-27-20, 01:35 PM
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Hot tub wiring question

I’ll be wiring a new hot tub: main panel-->conduit under house-->transition to underground conduit outdoors-->disconnect-->underground conduit & flex conduit to tub
- also adding two 120v outdoor outlets at the same time

This is the current plan:
  • 70 amp breaker at house main panel
  • 6 gauge, 4 wire (THHN) from house main panel to disconnect, through 3/4” conduit
  • disconnect = 50 amp CGFI breaker with two additional 15amp circuit breakers (this one: https://www.spadepot.com/MW-Spa-GFCI...10588C193.aspx)
  • three lines emerging from the disconnect:
(1) 6 gauge, 4 wire (THHN) to tub from 50amp breaker at disconnect; through ¾” rigid conduit then transitioning to flex conduit to connect to tub itself
(2) first 120v 12/2 UF wire from 15amp breaker at disconnect, through ¾” rigid conduit then transitioning to flex conduit to a 15amp CGFI outdoor outlet
(3) second 120v 12/2 UF wire from 15amp breaker at disconnect, through ¾” rigid conduit then transitioning to flex conduit to another 15amp CGFI outdoor outlet

Questions:
  • Any issues with the above specs?
  • Is 6 gauge sufficient?
  • can I use a 60amp breaker at the house instead of 70?
  • Is the 12/2 ok with 15amp breakers?
  • Currently the plan is to route both of the 120v outlets from their own breaker in the disconnect box, but I suppose I could wire from a 15a breaker in the disconnect to the first outlet, and connect the second outlet in series from the first…might be better?
  • What kind of conduit should I use under the house? Was planning on flex conduit.
Thanks for any input, I really do appreciate the help.
 
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Old 10-27-20, 03:22 PM
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#6 is too small for 70 amp. It is limited to 60 amp. You will need to go up to #4.
 
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Old 10-27-20, 03:40 PM
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Thank you.
a) Can I use 60 amp instead, with everything else remaining the same? Or was I correct assuming I needed 70amp at the main panel?
b) If not, and I used #4, I believe I will also need to go to 1" conduit, correct? Or, assuming I can pull the wires (it's nearly a straight shot), can I stick with 3/4"?
c) Alternatively, could I use only one 120v 15amp outlet (rather than 2) in addition to the 50amp/240v and stay with #6?

 
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Old 10-27-20, 04:49 PM
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All of today's panels and breakers are rated 75C and if the #6 conductor after de-rating is still rated 65 amps (75C column) then you can use a 70 amp ocpd as long as the calculated load is not more than 65 amps.

You need to make sure your wire is rated THWN or THWN/THHN.
4 #6's is max in a 3/4" pipe. Will actually be snug.

You could protect the circuit at 60A and just put both new receptacles on a single 20A breaker.
 
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Old 10-27-20, 05:06 PM
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Where in the NEC is it stated that when the next standard size breaker is used that the calculated load is not to exceed the conductor ampacity? I'm not seeing it in 240.4(B).
I know 310.15 sets the ampacity, but it's not clarified in 240.4 when going up in size on the breaker.
 
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Old 10-28-20, 03:08 PM
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Thanks, useful idea to use 60amp breaker at the main panel and 50amp (tub) & 20 amp (for the outlets/receptacles) at the disconnect. I think this means I can stick with the #6 gauge 4 wire and the 3/4" pvc conduit, which is also good.
 
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Old 10-28-20, 04:20 PM
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You can save a few dollars on your Midwest 50 amp spa panel, this is the same as you linked to except it's cheaper.
https://www.homedepot.com/p/Midwest-...250P/100686230

Or, you can save even more by using this 50 amp spa panel except this one only has two spaces so the circuit for the outdoor receptacles would have to come from main panel. In this case, I'd enlarge the feeder conduit to 1".
https://www.homedepot.com/p/Square-D...0SPA/205170085

Seems like just a few years ago that the Midwest spa panel was the best buy at only around $70 at both Lowes and Home Depot.
 
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Old 10-29-20, 02:42 PM
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Thanks for the tip on the same disconnect for less $ at HD. Can I still use 60amp at main panel (6 gauge, 4 wire still) if i have the 50amp CGFI and two 15amp branches at the disconnect?
 
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Old 10-29-20, 03:54 PM
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Can I still use 60amp at main panel (6 gauge, 4 wire still) if i have the 50amp CGFI and two 15amp branches at the disconnect?
Sure, but I'd use 3 - #6 and 1 - #10 Grd for the feeder and 20 amp single pole breakers for the receptacles. I never recommend 15 amp breakers for anything except lighting circuits with few exceptions.
 
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Old 10-29-20, 04:01 PM
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@ joe .... question. Since this is going to a spa panel.... I don't usually reduce the ground size.
 
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