Question about running 220V for a hot tub

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Old 11-27-10, 06:40 AM
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Question about running 220V for a hot tub

I am new to the forum and do not know much about home electricity. Hence the post. I am going to run 220 for an indoor hot tub, actually I am hiring an electrician to do this but would like to be better informed beforehand. I have an existing line that used to run my electric furnace before replacing it with gas. I am hoping I can use this existing line as it will be tough to run a new line to the main panel due to the finished ceilings. I am hoping we can install a sub-panel at the end of the old furnace line and then continue with a smaller line (6ga) to the hot tub. The sub panel would include a 50amp GFI breaker I would assume. The old furnace line has 2 black insulated wires and one stranded uninsulated wire. These 3 lines are housed within a heavy gray sheath. The line runs to a 100amp breaker in the main panel. Obviously this line ran my furnace a few years back, but can I use this line as the basis for my sub-panel that powers my hot tub?

I have an electrician coming out but just want to have more knowledge beforehand. Thanks!

Al
 
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Old 11-27-10, 07:40 AM
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Originally Posted by sbman79 View Post
The old furnace line has 2 black insulated wires and one stranded uninsulated wire. These 3 lines are housed within a heavy gray sheath.
Al,

The cable could possibly be re-used if the bare wire is copper (not aluminum) and the new tub is a 240V-only model. However, most tubs require 120/240V which means a new three-conductor with ground cable would need to be installed back to the main panel.
 
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Old 11-28-10, 09:21 AM
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The tub specs simply state 240V / 50A so it sounds like I may be OK from that perspective. However, the wiring I have is aluminum not copper. So even though I could run copper 6ga from the breaker to the tub (roughly 20 feet) I should not use the existing line to feed the sub-panel because it uses alumimum wiring? Does it help (or matter) that the existing line is so much over-kill than what I will be using for the tub? As you can tell, I really want to make sure I cannot use the old aluminum line before throwing in the towel. Of course safety is primary.

Al
 
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Old 11-28-10, 09:43 AM
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What make and model tub are you putting in?
 
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Old 11-29-10, 04:06 AM
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I am putting in a tub from Sundance Spas. The model is called Chelsee.
 
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Old 11-29-10, 06:40 AM
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OK...Page 16 here..http://www.sundancespas.com/Communic...very_Guide.pdf will give you the specs. May want to bump up to a 60 A if possible...otherwise your heater won't run when the pumps are on.
 
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Old 11-29-10, 09:15 AM
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The electrical code does mandate that the ground wire for a spa be copper, so from a code point-of-view I do not think this cable can be re-used. You could discuss this with the electrician and/or inspector for a possible variance from the code. Inspectors are sometimes lenient when the complexity or expense of the "right way" is high.
 
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Old 11-29-10, 09:22 AM
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Ben...
How do they normally interpret that? Would the cable running from the spa to the sub have to be copper...but the aluminum from sub to main might be OK?

Just wondering.....
 
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Old 11-29-10, 09:38 AM
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I don't recall the code number off the top of my head, but there is one in article 680 that states essentially that a subpanel which is newly installed for a pool or spa also must comply with the same requirements as the pool and spa branch circuits, namely an insulated copper ground. There is an exception for existing subpanels which perhaps you could be persuasive about, but I'm pretty sure the intent of the code is that the entire grounding system for the spa be copper.
 
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Old 11-29-10, 10:57 AM
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Thanks for the detailed responses and the link to the specs page for my hot tub. Side stepping the copper issue for now, it looks like I may have to put my GFI breaker at my sub-panel because I don't think they make one for my main panel. If this is the case, it looks like I would have to run a 4 wire cable to the sub-panel and could not re-use the old 3 wire line. I am getting this from page 24 of the book (link above). If this is the case then the copper issue becomes muut because I would have to run a new line anyway. Does this seem correct?
 
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Old 11-29-10, 11:27 AM
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Yes that's correct. If they do not make a GFCI breaker for your main panel, you are almost certainly looking at installing a new cable anyway.
 
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Old 11-29-10, 02:57 PM
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I'm no pro, but I thought I'd seen 220V GFI breakers that did not require a neutral. If I understand correctly, the only reason neutral is needed for the GFI breakers is to give a place for the current leaked during the test function to go, but with a 220V circuit, it is possible to leak from one hot to the other for the test, so some GFI breakers work that way.

Definitely will need the input from the pro electrician, and the OP may have some luck asking the local building dept (inspectors) about what is required.
 
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