Prepping for eventual hot tub

Discussion in 'Electrical Forum discussion & Blog' started by peaks, Feb 19, 2014.

  1. peaks

    peaks New Member

    Messages:
    1
    Location:
    California
    Hello,

    I've been doing quite a bit of researching on this, but wanted to run by the board my plan and a couple of questions.

    Background: House is a 1950s mid-century modern in San Diego; house is concrete block construction. I want to prepare for a hot tub at some point. Hot tub location would be near a 90A subpanel that has capacity (I did the load calcs). With some other remodeling going on, I have ok access to the panel and to where I'd exit the house with the wiring. Basically, it's a good time for me to run the inside of the house part of the wiring now and I"ll complete the outdoor portion later.

    I plan to run a 50A GFCI circuit with 6/3 w/ ground NMB from the subpanel to where I'd exit the building (top plate above concrete block) and mount the spa disconnect (which is greater than 5 feet away from where the hot tub would be located). From the spa disconnect, I'd run 1" PVC conduit to where the hot tub would be located and eventually pull 4-wire 6AWG THWN.

    My questions:

    1) I know it would be better to run conduit even inside, but it's going to be pain to make that work. Can I use the NMB inside? There seems to be debate about whether this is acceptable due to whether to classify as a branch circuit or feeder given insulated ground issue.

    2) Assuming I can use the Romex inside, what's the best way to transition from NMB to outside? I know NMB can't be used outside (even in conduit), but does the code that allows NMB to be inside of conduit for a short distance for protection allow me to take it down the spa disconnect inside a piece of 1" PVC conduit off a LB? Otherwise I assume that I'll have to put a big 6x6 waterproof junction box where the cable exits the house and splice to THWN there before going down to the spa disconnect - I'd rather avoid those splices if I can.

    Thanks for the help.

    peak

    Read more: http://www.************.com/forum/e...-prepping-eventual-hot-tub.html#ixzz2tmvvw4ct
  2. Homeownerinburb

    Homeownerinburb New Member

    Messages:
    525
    Location:
    Los Angeles, CA USA
    1) I'd certainly have a word with your local inspector. I find they are generally pretty reasonable, and might let you bend a rule slightly as long as you are not obviously doing anything dangerous.

    That said (and btw, please don't use the trademarked name of NM here) I don't understand why you need to exit the house and then run down to the disconnect,(which should have a gfi breaker in it, just saying)? Why cannot you bring the NM out at the same height as the disconnect, or place the disconnect at the same height as you come out the wall, such that the NM enters directly into the back of the disconnect?

    Either way, while I cannot say as a flat out fact, I am pretty sure that you would be allowed to run the NM down conduit. You could use thin wall metal or non metallic, either one. Metal conduit needs to be bonded to the grounding wire. Classically one needs a specific coupling at one end of the EMT that clamps to the EMT and crimps the NM. This is both an anti-chaffe and an anti-tug tool. You gotta clamp the NM down somewhere.

    This is the sort of thing you could use:

    http://www.homedepot.com/p/Halex-1-...0ubboZ1z0uetqZ1z0ugmeZ1z0ugndZ1z0ugnqZ1z0v4pe
  3. Homeownerinburb

    Homeownerinburb New Member

    Messages:
    525
    Location:
    Los Angeles, CA USA
    And why is it an issue to run conduit inside? Remember that if you really want to, you can cut notches in the face of studs just deep enough to take conduit, and cover it with a nailing plate and then the wall board.
  4. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,531
    Location:
    North Carolina
    680.42 addresses hot tubs that are installed outside. .42(A)(1) allows for as much as 6 feet of flexible raceway such as LFMC or LFNC on the outside skirts of the tub. .42(C) allows a covered equipment grounding conductor on the interior of a dwelling but the key to the EGC is interior.

    NM-B cannot be installed in a wet location, 334.12 and the interior of a raceway installed in a wet location is a wet location, 300.9.
    NM-B can be installed on the interior of a dwelling for a hot tub at which point it should be changed to a conductor that contains a “W” in its title.
    680.42 also states that a hot tub installed exterior comply with Parts I and II of 680.
    680.21(A)(1) tells us the type of raceways that are allowed to supply the branch circuit to motors associated with pools, rigid metal conduit, intermediate metal conduit Sch. 40 or 80 PVC. Everything except the heater of a hot tub is driven by a motor, the jets as well as the bubbles.
    680.21(A)(1) also tells us that which ever of the four raceways we decide to use it shall contain an insulated copper equipment grounding conductor no smaller than a 12 AWG.

    As a code enforcement official those things pointed out above are going to be some of the but not limited to those things I will be looking for when doing my inspection.
  5. Homeownerinburb

    Homeownerinburb New Member

    Messages:
    525
    Location:
    Los Angeles, CA USA
    Can he have the disconnect where the NM-B comes out of the house, transition to rigid conduit of some sort, and then transition to no more than 6' of flex conduit?

    It is a matter of line of sight from the disconnect to the equipment, yes?
  6. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,531
    Location:
    North Carolina
    That would depend on the inspector that is doing the inspection. If I am the inspector the NM will have to end on the interior because 680 only allows the covered EGC for interior and not exterior, on the exterior it has to be insulated

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