Hot Tub GFCI Question

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  #1  
Old 09-19-04, 05:47 PM
Paul_OS
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Hot Tub GFCI Question

Getting prepared for the delivery of the new Hot Tub in about a week. The Tub will sit about 5 feet away from the detached garage, (garage is about 60' from the main house). I wired underground and installed a 100amp subpanel in the garage to feed the Tub and some shop tools. Every thing is by the book. I'm not an electrician but I do work for an electrical contractor. I ran everything by the guys at work and they double checked all the codes for me. I plan on having one of them drop by and check all my work before powering up.

Here's the question. I installed a Weatherproof 240V/60A GFCI on the outside of the garage next to the tub (5' away by code). Per the spec sheet that came with this GFCI which is made for Hot Tubs , I ran (3) #6 Red, Blk, Wht and (1) #8 Green/Ground. The unit has a 2 Pole breaker and has a Neutral Pigtail already prewired for the GFCI. You basically just bring in all 4 conductors in to the line side and hook them up, pretty easy.

It then states that you come out of each pole of the breaker (2) and also come out of the bottom of one of the breaker poles with the load (Tub) neutral. They give you a screw terminal on one of the breakers for this connection. Also you bring out your ground too. So 4 wires in and 4 wires out to the Tub. Again pretty straight forward.

Here is where it gets tricky. I downloaded the preinstallation manual for the Tub to make sure everythiing was correct and ready. They make about 10 different models. I found the hook-up diagram for the Tub I bought and it cearly shows the interconnection from a GFCI to my Tub. However, my Tub only takes (3) conductors not (4). They show the (2) hots and the ground only to the Tub, no neutral. Some of their other models take all (4), but not this and 2 other models.

It all seems very strange, and of all things, I'm not messing with a grounding issue related to water I plan to sit in.

So basically I'm stuck not using a terminal in the GFCI that is clearly meant to be connected. But it would be to a Tub that would have no terminal to connect to. The Tub diagram shows that it will come shipped with (3) Terminals, hot-hot-ground.

Sorry so long winded, I just wanted to express clearly my question. Anyone ever come across this before? I was looking for some input before calling the factory and listening to their pretty "on-hold" music.

Thanks in advance
paul o's
 
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  #2  
Old 09-19-04, 06:03 PM
Speedy Petey's Avatar
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If your tub does not require a neutral that is fine. Hook up the line neutral from the breaker as usual but DO NOT connect anything to the load terminal.

You have a 240 volt tub, not a 120/240 volt tub. Yours requires no neutral, that's all. Everything else stays the same.
 
  #3  
Old 09-19-04, 06:18 PM
Paul_OS
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I can see why you're speedy Pete, 10 minutes and I have an answer, wow! I wish I had you around when I was dragging (4) 150 foot #2's all over the backyard and then snaking them underground.

I will do as you say. But just to learn a little more about ground fault sensors, they must do all their work between the hots and the ground? Is that only where the GFI circuitry monitors? It never references the neutral? Or does it reference when you have a 120V and not a 240V?

Thanks for your help
paul o's
 
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Old 09-19-04, 06:49 PM
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GFI's do not need a ground to work. As you can see on the breaker they have no ground connection. A GFI device only needs a ground to pass on the ground to the circuit and to ground the yoke.
A GFI monitors the amperage between the line and neutral. In the case of a two pole breaker between line and line (and neutral). Any imbalance indicates leakage to ground, even though it does not use the ground to sense this. Basically if there is an imbalance it has to be going somewhere.
 
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Old 09-20-04, 04:33 AM
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The only purpose of the ground on the GFCI is for the test capability. When you press the test button a small amount of current is allowed to "leak" out the ground terminal. The amount is enough to trip the GFCI, which tests the GFCI circuitry. This is why if you have no ground you cannot test the GFCI circuit using the internal test button.
 
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Old 09-20-04, 06:35 AM
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Sorry Bob, but that's not correct. The test button on the face of the GFCI does not use or rely on the grounding connection for the test. The internal tester still works perfectly without a grounding connection. It's an external plug-in tester which needs the grounding connection.
 
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Old 09-20-04, 06:45 AM
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Sorry, I stand corrected. Was this true for older GFCI receptacles?
 
  #8  
Old 09-20-04, 08:13 AM
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No, I don't believe so. The test button on the GFCI is connected to the internal electronics. As such, it has access to both line and load, and both hot and neutral. So it can shunt some current from line side hot to load side neutral, or load side hot to line side neutral, and trip the GFCI by unbalancing the current that way. Note that there is no way that an external tester can do the same thing, since it only has access to one hot and one neutral through the faceplate slits.
 
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