Hot Tub wiring question

17 years ago

I will be relocating a hot tub and will take the existing sub-panel with 50A GFI breaker with it. My question is regarding the wire needed from the main to the sub-panel at the new location. The sub will be approx 200' from the main so I am thinking #4 copper or #2 aluminum THWN in Sch 40 buried approx 18". The problem I am having is finding the wire and it's price. Any suggestions, changes or substitutions that I can make?

Thanks,

Steve

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Comments (8)

kurto
17 years ago
Where are you looking for #4? It's generally available at electrical supply houses.
ibelieve1
Original Author
17 years ago
Have tried to find it online (with out much luck ... probably just not looking at the right places) Lowes, Ace, HomeDepot. I will see what is listed in the YellowPages under electrical supplier. I would think they would show up on the internet, though.

Is this run to long for #6, as it seems to be more readily available.

Not sure of the formula for voltage drop. Maybe I will do a search. The documentation I have is a bit older and shows #4 with a 2% drop at 180 feet.

Thanks,
Steve
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I agree with the guys in the electrical forum. When I hear statements like this it frightens me to know that they're fixing to do something like energize a portable tub on the advice of a Home Depot aisle worker. QUOTE" At the service panel end I'm presuming I'll connect the red and the black to the breaker and the other two wires to the ground bar. At the other end of the cable, where it hooks up to the GFCI, is there anything special to know or will that wiring be obvious? He told me that the wiring the guy at Home Depot recommended has 4 conductors encased in a flat cable; 3 of the conductors look to be about #8 stranded, and the 4th conductor is much smaller diameter. He also has a weatherproof hookup box that contains a GFCI, which I haven't looked at yet. "QUOTE Whatever you do DON"T TAKE A JOB LIKE THIS LIGHTLY. Your safety and that of the bathers depends on an installation that meets code. Here's what I use for my installs. 60amp 240volt GFCI breaker installed at the existing power center or a sub panel (NO EXCEPTIONS) 2 #4awg 1 #6awg 1 #8awg, I use THHN/THWN inside of 1 1/4" sch40 a&u conduit. Mine may have higher amperage loads because the pumps are 5hp each so I have a larger breaker and wire size than you might need. IMO, if your unable to determine your amperage load and size the appropriate breaker/wire size for the tub and are unclear on the manner of wiring in a GFCI breaker "PAY A PRO" just my .02 See ya, Kelly
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I'm not up on the Canadian codes but the following is per the US NEC. There are two things that are required for spas. I believe you are getting them confused (happens often). The first is the maintenance disconnect. The disconnect box can be located as close as you like. It needs to be within sight of the person who might be working on the mechanicals of the thing. For instance, in my case, the tub is mounted in the deck, the disconnect is under the deck which is where you get at all the machinery. This disconnect you MUST have. The second is the emergency stop switch. This needs to be located in sight of the spa occupants but not closer than five feet. This is the thing that is NOT REQUIRED for single family residences. If you have teck armored cable, you have to use the fittings. That's the only way cable is listed to be used. If you don't do this you are not assured of either water proofness nor ground bonding. There's nothing wrong with either option for the connection to the panel you describe in #3. Yes Teck doesn't need conduit. "LB" is a conduit fitting which you don't need either.
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Any time you get a shock, which is what you're getting, it's serious. What if someone with a heart condition got a shock from your hot tub by just putting their hand in the water. Does the word "lawsuit" come to mind? This has nothing to do with the GFCI breaker. You can try to find the problem with a good voltmeter. Set the meter to V AC, on a low scale, say in the 50V AC range. By touching each metal part of the tub and the ground wire, something will show a voltage significantly different than the other voltages from the metal parts. That'll be the part of the tub that's not bonded correctly. It will do this even with the breaker off because the ground wire will contain voltage. Because all parts of the tub are not at that same ground voltage, current will flow, and a shock results when current flows from a higher voltage to a lower voltage. By having everything bonded, even though there is ground voltage in the bonding system, it's all at the same voltage and therefore no current will flow and there will be no shocks.
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kurto
17 years ago
Given the length of the circuit and the draw, you should be using #4. I think it's not that available on the web because it's heavy, and therefore the shipping negates any price advantage that might otherwise be available.
DavidR
17 years ago
You can find a voltage drop calculator here.
ibelieve1
Original Author
17 years ago
Thanks for all the information / help. It is greatly appreciated!!!

I have calculated the voltage drop using the equation reference above and using another have found. Using the calculator above, I get the following results (200' run, 50A, 240V):

#6 9.5V drop 4%
#4 6.0V drop 2.5%

The other formula I used gave slightly lower results.

It seems like 4% is real borderline. I will check the distance and if less than 200', might consider #6.

My understanding is a max of 3% for the sub so that the total does not exceed 5%. I am on a dedicated transformer providing a 200A service within 100' of the home. Have no idea the size of the feeder line. The house is all electric but is not large as it is a weekend place.

Thanks,
brickeyee
17 years ago
Unless you want to purchase an entire spool of wire, find an electrical supply house that sells cut lengths.
joefixit2
17 years ago
When calculating voltage drop you use the total connected load, not the circuit size. Look at the nameplate on your spa to get the total KW. Add in anything else you plan to connect to the sub panel that could run at the same time as the spa,if anything, and use this figure for the calculation. Your spa will not use 50 amps, probably more like 30 to 40. This would easily allow the smaller wire.
joefixit2
17 years ago
Last week I paid .87/ft for #4 THHN, that was the roll price. I haven't bought any #6 for about 6 weeks, last time I paid .67/ft, roll price. I think the prices at the big box stores are about the same.

Hot Tub wiring question

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Hot Tub wiring question

Comments (8)

kurto

ibelieve1Original Author

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DavidR

ibelieve1Original Author

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