Power inlet fro xfr switch

Discussion in 'Electrical Forum discussion & Blog' started by homer777, Oct 16, 2010.

  1. homer777

    homer777 New Member

    Messages:
    13
    Location:
    nh
    Hi,

    I didnt get around to putting in the xfr switch last year, so let’s see if I can get it done.

    A couple of quick questions, maybe more later. (I got the pic online and is just for reference.)

    My switch will be 30 away and I will be using 4 #10 thhn in sch 40.

    1. What height should the power inlet be installed at..?
    2 My outside wall between the garage doors looks like the pic. The conduit will come down the wall and I will put some type of pull elbow where it makes the 90 to go through the wall....Can I just go in the back knock-out or do I have to go in the bottom knock out? If the back one, do I just cut a piece of sch 40 to go through the outside wall and put on some type of male fitting with some type of water proof washer?? ..and what would be the proper way to go from the pull elbow to the bottom knockout if that is by code? (I’d rather go in the back, so it won’t be seen (no jokes)).

    Thanks in advance,
    Homer

    Attached Files:

  2. Jim Port

    Jim Port Electrical Contractor

    Messages:
    156
    Location:
    Maryland
    You can mount the inlet at whatever height you like.

    Pull L's cannot be used inside the wall. You need access to the cover plate.
  3. homer777

    homer777 New Member

    Messages:
    13
    Location:
    nh
    I thought there might be some type of height requirement because of snow, etc.... I d like to mount it at least 24".

    That pull elbow I mentioned will not be in the wall, it will be on the garage side of the wall.

    Thanks,
    Homer
  4. Furd

    Furd Engineer

    Messages:
    446
    Location:
    Wet side of Washington State
    [​IMG]

    [​IMG]

    Steel nipple through the back of the power inlet, through the siding and sheathing into the 4-inch J&P box and then flexible conduit to the transfer switch. I cut back the siding so the inlet box is slightly recessed and caulked the top and both sides.

    Don't forget to add equipment grounding pigtails to all metallic parts that may not be bonded by the conduits.

    Keep the bottom of the inlet box about a foot (or more) above the normal snow line for the location. Since snow is rare in my area I put mine about 30 inches above grade.
  5. homer777

    homer777 New Member

    Messages:
    13
    Location:
    nh
    Thanks Furd,

    I like the idea of cutting the siding, but I'd rather not mess with the vinyl. I think I might use one of the mounting blocks that are used on vinyl. I already bought all the sch 40 pipe, so I'm looking for the proper connector for sch 40.

    Thanks,
    Home
    Last edited: Oct 19, 2010
  6. Furd

    Furd Engineer

    Messages:
    446
    Location:
    Wet side of Washington State
    My previous house had vinyl siding but it was before the availability of the mounting blocks so I can't offer any advice there. You could cut back the siding and use J channel to make a vinyl "box" around the inlet box.

    The proper way to use the PVC conduit includes using threaded adapters on the ends. If you have sufficient room in the wall I would suggest the threaded adapter into the back of the power inlet box, conduit through the wall and either into the back of a J&P box, a "pulling elbow" or a PVC LB fitting.
  7. homer777

    homer777 New Member

    Messages:
    13
    Location:
    nh
    When putting cable into a metal box, you use a cable clamp. Is anything needed when putting sched 40 into the back of the power inlet (there will four 10ga wires) ?...also my xfr switch has what I think is liquid tight that houses the wires that are to go into my electrical panel....is anything needed there in regards to protecting the wires?

    Thanks.
  8. Furd

    Furd Engineer

    Messages:
    446
    Location:
    Wet side of Washington State
    You need to use a threaded adapter on the end of the PVC conduit where it goes through the back of the power inlet box and use a locknut (steel) on the inside. A plastic threaded bushing, while not required for 1/2 or 3/4 inch conduit is not a bad idea in addition to the locknut.

    Liquid tight conduit has special fittings to adapt it to threaded connectors. These are available in straight, 90 and 45 degree models.
  9. homer777

    homer777 New Member

    Messages:
    13
    Location:
    nh
    This is the male adapter that I will get. Steel locknuts fit sch 40 fittings like this? Not sure what you meant about a bushing. Would you thread that on the male adapt. after the steel locknut?

    Thanks again..

    Attached Files:

  10. Furd

    Furd Engineer

    Messages:
    446
    Location:
    Wet side of Washington State
    Yes, that's the adapter and yes again, steel locknuts work on those fittings. The bushing would screw on after the locknut although it technically isn't necessary on 1/2 or 3/4 inch conduit.

    I suggest using a pair of channelok pliers to tighten the lock nut rather than a hammer and screwdriver. Using the latter tools can break the plastic fitting. Remember it only needs to be tight enough to not loosen afterward, you're not trying to make a ground connection.
  11. homer777

    homer777 New Member

    Messages:
    13
    Location:
    nh
    Once again, thanks.

    One more question. To make this exterior power inlet water tight, would I put some type of gasket between the back of the power inlet and the male adapter or between the inside of box and the locknut?

    Thanks again.
  12. Furd

    Furd Engineer

    Messages:
    446
    Location:
    Wet side of Washington State
    You could smear some silicone caulk around the fitting after tightening it to the power inlet box. Sealing from the inside is futile. Be sure to caulk around the top and sides of the box after mounting but leave the bottom of the box unsealed to allow any moisture that may get behind the box a place to drain.
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