Spa power Question...

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  #1  
Old 08-01-13, 11:58 AM
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Question Spa power Question...

I've read a thousand posts about others having this same confusion.. most say to get an electrician..

HOWEVER.. I will be doing this myself, but wanted to be sure I understand this correctly..

My spa is a 240v unit.. it says it draws 40/48 AMPS.. single phase 60hz..

I need to put in a 1 pole 30 AMP GFCI breaker.. My understanding is this..

I can run 4 10 gauge wires from my spa (L1, L2, C, G) to my breaker.. L1, L2 and C wired onto the breaker and the ground to the ground bus bar.

If I understand this correctly, each leg can carry up to 24 AMPS, of the 48 total listed on my spa pack.. meaning 10 gauge wire is ok.

Questions are:
1) Am I understanding that the 2 legs each carry half the load...
2) If my assumption 1) is correct, then the dual pole 30A breaker is fine?

The spa came with 10 gauge wires already on it.. my initial thought was.. Oh no.. 10 gauge for a 48A spa!!! But if each leg carries half of the 48A that the unit sticker claims, then 24A is all each leg could carry and the wiring makes more sense...

Am I on the right track?

Thanks in advance!
 
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  #2  
Old 08-01-13, 01:07 PM
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Sorry, but no.

1) No. Each leg carries the full load current. 48 amps in, 48 amps out.

2) So since your assumption is not correct the 30 amp breaker and #10 wire will not work.

You need #6 copper wire (hot, hot, neutral, ground) and a 60 amp breaker. You need a 60 amp because you may only load a circuit to 80% continuously. (more than 3 hours) 80% of 50 amps is 40 amps and 80% of 60 amps is 48.

You will find spa disconnects with GFCI breakers fairly easy in 60 amps.
 
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Old 08-01-13, 01:26 PM
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Is your spa indoors or outside?
 
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Old 08-01-13, 01:43 PM
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It is an outdoor spa... the people I bought it from had 10 gauge wire on it for years.. the wire is still on it.. I saw it running, heated, with lights and radio going.. I don't see how those wires didn't melt if 48Amps were running through it..

60Amps would need 4 gauge wire? I can't think of any standard sized spa that used that sized wire??
 
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Old 08-01-13, 01:51 PM
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Number 6 copper THHN/THWN would be the proper size and type.
 
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Old 08-01-13, 02:18 PM
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All the spas I have wired over the years require a 50 or 60 amp feed, depending on the spa.

The wires may have not melted, but I bet they were pretty dang hot!
 
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Old 08-01-13, 03:11 PM
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Its not so much the wires as the insulation that degrades and eventually fails due to the overheated wires.
 
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Old 08-02-13, 06:40 AM
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Interesting! Thank you everybody. It is nice to be able to discuss without being flamed for my ignorance!
The previous owner of my spa sent me photos of their now disconnected breaker that had been used for this spa for years.. they were using a 30 amp breaker.. with the #10 wire.. That seems fine, but I just don't see how the spa kept from popping that breaker every time the heater came on.
The 'spa pack', which is a Hydro-Quip CS6200, shows that the spa is 240 volt, 40/48 Amps, single phase 60hz unit.. Since it is a 40/48 Amp unit, how is it possible that a 30 amp breaker didn't constantly trip when the unit was in use?
I have a 30 amp GFCI and a 60 amp GFCI coming today.. One will need to be returned.. but now I'm wondering which one! I was given some #10 150C High Temperature wire.. Which I'll use until I can afford the 100' of #6 I need to run the L1,L2,C,G wires from spa to panel..
 
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Old 08-02-13, 06:54 AM
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Sometimes a spa has a "low amperage" setting where the heater and pump don't run at the same time. That might be how they got away with it.

I was given some #10 150C High Temperature wire..
If there is no W in the designation it is not for outside use. If you use it you need to use the 30 amp breaker. In my opinion you should not use the wire. Get the correct gage wire and use the 60 amp breaker.
 
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Old 08-02-13, 08:26 AM
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I've seen the "low amperage" setting on spas, that Ray is referring to, as a wire jumper inside the spa pack. If it's really set to 30A, then #10 and a 30A breaker is perfect.

Some spa manufacturers buy the spa packs in bulk and use the same one on the biggest spas to the smallest. What's written on the spa pack is just it's maximum and may not be what your model actually draws. Look for a nameplate with the spa model # on it. Ignore all the individual nameplates on motors and heaters. If you find it, the Minimum Circuit Ampacity (MCA) is the UL rated ampacity that's legal for the wires.

If you don't find it, I'd need volts and Hp off every motor and volts/amps/watts off every heater to do a calculation.
 
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Old 08-02-13, 08:43 AM
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I looked and my spa pack is a Hydro-quip CS6200-U model... the documentation I find for the "U" model shows the following.. which, maybe, is how they ran it with 30A & #10.. The LC option is the 'default' option, as indicated by the *


Current Limiting:
HC = High Current (No Current Limiting)
LC = Low Current (heater will turn off with high speed pump or accessory operation)*
 
  #12  
Old 08-02-13, 08:54 AM
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...You need #6 copper wire (hot, hot, neutral, ground) and a 60 amp breaker. You need a 60 amp because you may only load a circuit to 80% continuously. (more than 3 hours) 80% of 50 amps is 40 amps and 80% of 60 amps is 48. ...
UL has already used a formula equivalent to Tolyn Ironhand's 80% rule. No further derating is done to the MCA on the nameplate or ampacity in the owner's manual.

The table gives #6 Romex(NM) as max 55A. If the run is done entirely in conduit and individual wires that are THWN or better (moderately High Temperature wire), then the same table gives #8 as 50A.

That is, unless the owner's manual calls for bigger, two #8 hots, a #10 white(c) and a #10 green(g).
 
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