Hot Tub Wiring Question

ryan5068 · 06-06-2012, 03:57 AM

Hello everyone I have moved on to my next project and I have a few quick questions.

Just to put it out there right away I have a certified electrican helping me on this project to look over final hook up and verify I did everything right before turing on.

I am buying a hot tub that requires 240V/50Amps. I know I need the 4 wires in THHN or THWN run through my conduit that is 1". Okay all that is good.

What wire size do I need to run for each color? I am thinking the two Hot (blacks) need to be min #8 or possibly #6. But I am most unsure about the common and the ground sizes? Can they be smaller since they are not carrying the load?

Stranded Wire or Solid Wire??? I do have some 90 degree gradual curves where I am pulling wire.

Also does my double beaker at my main panel box need to be GFCI or just the one (50Amp) in the spa pack located on the outside of the house.

I wouldn't think they would both be GFCI but I want to check before I buy the product.
My run is going to be no more than 50' feet. Thank you all

Jim Port · 06-06-2012, 05:21 AM

Two #6 blacks are good, a #6 white and a green. The instructions may call for a full size ground, otherwise a #10.

They need to be THWN if used outside. They will be stranded.

The GFI protection can be inside or outside.

Glennsparky · 06-06-2012, 05:27 AM

Your pipe is a wet location so the wire rating has to have a w in it. #8 thwn copper for two hots and #10 thwn copper for green and white. The 8 will only come in stranded. You might as well get the 10 in stranded, too, but it doesn't matter electrically. Only one gfci per circuit, do not put them in series. If the main panel is less than 50' and in sight of the spa, you should not need a disconnect ( spa pack/breaker) closer to the spa. Local codes may vary. You would then run the pipe directly up into the spa with no splices or boxes. Your one gfci breaker would be in the main box.

Glennsparky · 06-06-2012, 06:08 AM

Jim typed quicker than me. He's right that the instructions may call for a bigger ground wire. And the inspecter will probably require the white wire be no smaller than the green. But, the white never carries much power. Sometimes just the electronics are 120 volts. Maybe also a motor or two. If the white ever had more than a dozen noncontinuous amps on it, it'd blow my mind. The 50 amps you quoted is the minimum circuit ampacity. Which means your spa is designed to pull less than 40 amps and the spa company already multiplied by 125% for what you read in the manual or on the nameplate. Check to make sure. If that's true, #8 wire is plenty for less than 70 feet of wire one way.

J. V. · 06-06-2012, 12:03 PM

Glenn. You cannot derate the neutral in this circuit. The neutral must be the same size as the two hots.

Glennsparky · 06-06-2012, 12:10 PM

Hi J.V., please explain.

stickboy1375 · 06-06-2012, 05:18 PM

Quote:

Originally Posted by Glennsparky

Jim typed quicker than me. He's right that the instructions may call for a bigger ground wire. And the inspecter will probably require the white wire be no smaller than the green. But, the white never carries much power. Sometimes just the electronics are 120 volts. Maybe also a motor or two. If the white ever had more than a dozen noncontinuous amps on it, it'd blow my mind. The 50 amps you quoted is the minimum circuit ampacity. Which means your spa is designed to pull less than 40 amps and the spa company already multiplied by 125% for what you read in the manual or on the nameplate. Check to make sure. If that's true, #8 wire is plenty for less than 70 feet of wire one way.

Most of this was just mass confusion... do you really think the OP understood any of this?

stickboy1375 · 06-06-2012, 05:21 PM

Quote:

Originally Posted by ryan5068

Hello everyone I have moved on to my next project and I have a few quick questions.

Just to put it out there right away I have a certified electrican helping me on this project to look over final hook up and verify I did everything right before turing on.

I am buying a hot tub that requires 240V/50Amps. I know I need the 4 wires in THHN or THWN run through my conduit that is 1". Okay all that is good.

What wire size do I need to run for each color? I am thinking the two Hot (blacks) need to be min #8 or possibly #6. But I am most unsure about the common and the ground sizes? Can they be smaller since they are not carrying the load?

Stranded Wire or Solid Wire??? I do have some 90 degree gradual curves where I am pulling wire.

Also does my double beaker at my main panel box need to be GFCI or just the one (50Amp) in the spa pack located on the outside of the house.

I wouldn't think they would both be GFCI but I want to check before I buy the product.
My run is going to be no more than 50' feet. Thank you all

I've wired a lot of hot tubs, and I'm betting on it requiring 4 #6awg conductors... The hot tub companies, are really hard up for a full size equipment ground.

mpoulton · 06-06-2012, 05:36 PM

Quote:

Originally Posted by Glennsparky

And the inspecter will probably require the white wire be no smaller than the green. But, the white never carries much power. Sometimes just the electronics are 120 volts. Maybe also a motor or two. If the white ever had more than a dozen noncontinuous amps on it, it'd blow my mind. The 50 amps you quoted is the minimum circuit ampacity.

There is no code provision which would allow the use of a reduced-sized neutral on this circuit - especially not one rated for less than the OCPD ampacity! The conductor ampacity and OCPD rating must jive, regardless of how light the load is.

I'm just curious now: is there ANY circumstance outside welders and motor/hvac loads where #10 wire could be used on a 50A breaker? I don't think so.

Code05 · 06-06-2012, 05:36 PM

Quote:

Originally Posted by stickboy1375

Most of this was just mass confusion... do you really think the OP understood any of this?

Heck, I cannot really understand it and I twist wires for a living.

stickboy1375 · 06-06-2012, 05:40 PM

Quote:

Originally Posted by Code05

Heck, I cannot really understand it and I twist wires for a living.

Me too, it was a long trip to nowhere.

stickboy1375 · 06-06-2012, 05:52 PM

Quote:

Originally Posted by mpoulton

I'm just curious now: is there ANY circumstance outside welders and motor/hvac loads where #10 wire could be used on a 50A breaker? I don't think so.

210.19(a) (3) exception no. 1

J. V. · 06-06-2012, 08:35 PM

Quote:

Originally Posted by Glennsparky

Hi J.V., please explain.

Here you go.

Quote:

Originally Posted by mpoulton

There is no code provision which would allow the use of a reduced-sized neutral on this circuit - especially not one rated for less than the OCPD ampacity! The conductor ampacity and OCPD rating must jive, regardless of how light the load is.

Derating the neutral is not allowed in this circumstance as mpoulton has explained above.
Derating neutrals are permitted in some applications. Not in this one.

Glennsparky · 06-07-2012, 04:18 PM

The run between the main panel box and what Ryan calls the spa pack is a feeder. Read 215.2(A)(1) Exception No. 2 and 215.2(A)(2).

stickboy1375 · 06-07-2012, 05:03 PM

Quote:

Originally Posted by Glennsparky

The run between the main panel box and what Ryan calls the spa pack is a feeder. Read 215.2(A)(1) Exception No. 2 and 215.2(A)(2).

Yes, but 99% of Hot tub manufactures still spec out the minimum size conductors you can use...