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Thread: Outdoor SPA, wire and GFCI Disconnect

  1. #1
    Join Date
    Nov 2006
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    Default Outdoor SPA, wire and GFCI Disconnect

    I would like some views on the on the following that I posted on a SPA HELP FOURM. I have been speaking to some electricians and spa people and get some different views. I put it out in a forum and got some comments that I was not expecting.

    I would like to get some views on my original wire question that I asked (using UF cable form the main box to the SPA 240V 50A GFCI Disconnect).

    I also received a comment about our plan to use a SPA 240V 50A GFCI Disconnect and not a circuit breaker disconnect. I have been reading some very different views on breaker GFCI vs. the 240 volt GFCI (Non breaker). Below I have posted my original question and the answer I received. Thanks I appreciate your assistance.



    My original question that I posted:


    •From Main electric box in basement run UF 6/3 W G wire from a 240 volt 50 amp circuit breaker (non- GFIC) to the outside wall, about 12 feet.

    •Go through wall into PVC conduit which will be located under the deck, attached to the joist, the run is about 12 additional feet.

    •Conduit will go to a SPA disconnect panel, located on the deck railing, that has 240 volt 50 Amp GFCI protection. Note this is a 240 50 amp GFCI, not a GFCI circuit Breaker (see this web site: http://www.spadepot.com/Merchant2/me...ct_Code=BX8001 to view this disconnect panel)

    •The SPA Disconnect Panel is located 6 feet from the spa.

    •From the SPA Disconnect Panel I will run 4 separate (3 plus ground) #6 THHN wires in conduit to the spa.

    We want to use UF cable so that I do not have to run conduit in the basement (pain in the neck). Is this allowable. I have seen different info on the web ranging from the ground not being insulated in UF Cable so it is not allowable to it is not allowable to have UF cable in conduit for a whole outside run.

    Spa Requirements 220 volt 50 amp dedicated circuit, number 6 3 wire with ground, Use THHN copper wire only


    Any advice? Thanks


    Reply I received:

    The wiring should be ok, however I cringe at that type of spa disconnect. It isn't a true fully GFI protected circuit. What it does is uses a small 120V GFI breaker to operate a contactor in the panel. The theory is that if there is a ground fault, it will trip the small breaker, releasing the contactor, thus disconnecting the whole spa. In reality, there can be an instance where the contactor gets welded in the CLOSED position, from arcing, and no matter what that little GFI breaker wants to do, the spa is being fed full power. So, situation is this: Heater shorts out, contacter welds since a shorted heater draws infinite amps (enough to weld), heater opens to the water, GFI breaker senses this and trips, but low and behold, the heater is still feeding deadly current into the spa, giving the occupants one heck of a ride.
    Personally, I would rather rely on a single device, rather than the 3 required in your application. If any one fail, the whole system can be left unprotected. With a single GFI breaker, they generally fail in a protected state, as long as it is a QUALITY breaker (spit on cutler-hammer here)

  2. #2
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    The best thing to do is talk to your AHJ (Authority having Jurisdiction. Example: Electrical inspector), and see what they will allow. You will find that some jurisdictions require you to run your wires in conduit, and some do not. The ones that do not, will allow you to run romex inside the house. Reason: Seems that no one can get a grip on the meaning of insulated ground. We run all our wires in conduit, and call it a day!
    Learning brings success. While you are waiting, I'm getting better!

  3. #3
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    Why do you want to use this instead of a 50A GFCI breaker? One issue I see with this is wether that 50A circuit becomes a feeder instead of a branch circuit because that GFCI box has a small breaker inside it (for the 15 to 20 amp convenience outlet). If this becomes a feeder, you can't use NM or UF cable between the main panel and this box.

    Yes, the contactor could weld itself, but GFCI breakers and receptacle can fail the same way when they have a short circuit. Short circuits are most damaging when they don't leak to ground (most likely failure mode of a spa pump motor), as a GFCI doesn't stop that but the upstream circuit breaker does. How do you think a GFCI receptacle works -- there's a mechanical interrupt when a ground fault occurs, and that mechanical release could fail or weld itself too. That is why GFCI breakers/receptacles have a TEST button and you should use it.

    It seems simpler to me to do one of the following:
    1. Use NM cable inside to a 2 slot 3R load center on the wall (use a normal 50A breaker in the main panel). Put a 50A GFCI breaker in this 3R box and wire it to your tub. I used to think this made the wires from the main panel a feeder, but I now understand that it does not (as long as there isn't an additional smaller breaker in that same panel). Then run a 12-2 circuit to an outside GFCI receptacle near the tub (but no closer than 5, or is it 10, feet from the tub) if there is no existing outside receptacle near by.

    2. Install a 4 slot 3R loadcenter using a conduit run from the main panel and use an insulated grounding wire (not just covered like NM or UF cable). This would need to be at least a 50A feeder and preferably 60A. Put a 50A GFCI breaker in the load center for the tub, and a 20A single pole breaker for the required convenience outlet. The convenience outlet would have to be a GFCI type.
    Last edited by suemarkp; November 3rd, 2006 at 11:43 AM.
    Mark
    Kent, WA

  4. #4
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    Both options listed by Mark will work, but find out which will suit your AHJ.
    Learning brings success. While you are waiting, I'm getting better!

  5. #5
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    Default update

    Some clarification:

    1. Small rural town no inspection or inspectors.
    2. I wan not going to use 15A Breaker. Just the 240V GFCI


    thanks Keithje

  6. #6
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    Then either option listed by Mark will work, and meet todays NEC standards.
    If you want to go with a standard two pole breaker to feed your Connect. GFCI protected spa panel, then go for it!
    Learning brings success. While you are waiting, I'm getting better!

  7. #7
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    Is there a reason you're favoring the large GFCI box instead of just using a GFCI breaker? That should cost less. You could even put the GFCI breaker in the main panel and use a 60A air conditioning disconnect for the hot tub disconnect (only a pull out or non-fused tpe would be required with a GFCI in the main panel).

    If you use the box you originally suggested, you'd need to wire it as a feeder (which means conduit and insulated ground) unless you removed that small single pole breaker and put a filler plate in its place.

    I personally don't see much difference between a GFCI breaker or using the dead front GFCI box w/contactor. The latter is just more complicated.
    Mark
    Kent, WA

  8. #8
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    Default reply

    Two reasons for using the GFCI box
    1. Can get it for next for next to nothing at a store that is closing. (PS the box is not that big)

    2. Have read a lot of positives about the GFCI box vs. GFCI breakers regarding false trips and longevity.

    I would pull the small single pole breaker out and put in a filler. So If I do that then I understand you to be saying that I can
    1. Use UF and put it into conduit once we go through the wall to the outside and into the GFCI Box.
    2, Then from the GFCI box use THHN into the Spa (in conduit of course).

    Is that correct?


    Thanks everyone

  9. #9
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    If you install conduit from the house to the gfci panel you can use NM-B or Uf-b from the main panel inside the house to a junction box (if you blank out that 120V breaker in the gfci disconnect) just before you go outside. Then transition to thhn/thwn in conduit to the gfci disconnect. It is more common to use thhn/thwn in flexible liquid-tight conduit from the gfci panel to the control panel of the spa.

    It is becoming very common for the pool industry to suggest the gfci disconnect over the gfci spa breaker box. They are claiming that it eliminates 99% of false trips. Who knows? I dont see much of a disadvantage to either in the complete scheme of things.

    My opinion is if you use the gfci disconnect then dont get rid of the 120 volt accessory breaker. Go ahead and spring for the extra conduit and THHN/THWN with insulated ground all the way from the panel in the house to the gfci disconnect then liquid tight or rigid pvc from there to the control panel. You wont be out that much and will have the better installation as far as I'm concerned.

    The spa/hot tubs that we wire up are using the gfci disconnect box mainly to satisfy the installers/vendors. They tend to blame call backs for gfci trips on the gfci breakers being used. Frankly I dont get it. But we use them to keep the figure pointing to a minimum. The conduit in the house can become a PIA in finished interiors but I think you will be happier with this type install. Nothing wrong with the other suggestions either and I dont believe any of the methods provide any degree of greater safety.

    Roger
    Last edited by Roger; November 3rd, 2006 at 07:48 PM.

  10. #10
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    Yeah, we run conduit all the way--forget the rest!
    Learning brings success. While you are waiting, I'm getting better!

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