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Thread: Engine Block Heaters and GFCI Receptacles

  1. #1

    Engine Block Heaters and GFCI Receptacles

    I am a loss control / safety guy that works with several municipalities. I am curoius about the proper method to power a block heater from a receptacle protected by a ground fault circuit interrupter. The electrician tied the ground connection in the block heater to the heater frame and then opened the female end of an extension cord and disconnected the ground. He then plugged the extension cord into the GFCI receptacle and block heater. This may allow the circuit breaker to trip under a short circuit, but it may prevent the GFCI from tripping under a high resistance fault, which is what a GFCI is designed to do. Also, altering the extension cord to function other than as designed by the manufacturer may be exposing municipality to a citation and liability claim, specifically if that cord is mistakenly used in some other application.

    To recap, if a block heater is properly installed and the ground fault circuit interrupter receptacle is of the correct amperage and properly installed, the system should work without having nuisance tripping. If there is nuisance tripping that is indicating a problem that should be resolved and not bypassed. Am I correct?

  2. #2
    Join Date
    Mar 2003
    Location
    Minnesota
    Posts
    392

    Cord is not listed for that use.

    Have them do it right.

  3. #3
    Join Date
    Aug 2007
    Posts
    424
    If they're dedicated to engine block heaters and not intended for general purpose use by personnel, why would they need GFCI protection? :smile:
    Pretend I hooked them up without GFCI protection...cite me. :smile: (why do I think I'm about to learn something here?) :grin:

  4. #4
    Join Date
    Mar 2006
    Location
    close to greenville sc
    Posts
    1,013
    We hard wire all block heaters.
    Military wives deserve the Purple Heart Medal. They are wounded every time their Soldier goes off to protect our freedom!

  5. #5
    Join Date
    Feb 2003
    Location
    Wisconsin
    Posts
    8,752
    Quote Originally Posted by Loss Control Consultant
    To recap, if a block heater is properly installed and the ground fault circuit interrupter receptacle is of the correct amperage and properly installed, the system should work without having nuisance tripping. If there is nuisance tripping that is indicating a problem that should be resolved and not bypassed. Am I correct?
    Yes you are.
    Just because you can, doesn't mean you should.

  6. #6
    Join Date
    May 2005
    Location
    Richmond, Virginia
    Posts
    21,838
    Quote Originally Posted by hockeyoligist2
    We hard wire all block heaters.
    How do they drive the trucks away? :-?
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  7. #7
    Join Date
    Feb 2003
    Location
    Massachusetts
    Posts
    48,734
    Quote Originally Posted by LarryFine
    How do they drive the trucks away? :-?
    Long cords? :grin:


    I guess he is a talking about generator block heaters. :smile:

  8. #8
    Join Date
    Aug 2007
    Location
    Rhinelander WI
    Posts
    1,573

    Smile Engine Block Heaters

    Welcome to the forum. You are correct. A good electrician does not alter extension cords. We usualy end up having to repair cords that some knat brain has removed the ground from. Make em fix it!!:smile:

  9. #9
    Join Date
    Feb 2003
    Location
    Massachusetts
    Posts
    48,734
    Quote Originally Posted by lpelectric
    If they're dedicated to engine block heaters and not intended for general purpose use by personnel, why would they need GFCI protection? :smile:
    Under the 2005 NEC if they are

    1) Located at other than a dwelling location

    2) Are outside

    3) Are accessible to the public

    4) Are single phase 15 or 20 amp 125 volt receptacles, either single or duplex, straight blade or twist lock...

    210.8(B)(4) requires GFCI protection.

  10. #10
    Join Date
    Mar 2006
    Location
    close to greenville sc
    Posts
    1,013
    Quote Originally Posted by LarryFine
    How do they drive the trucks away? :-?

    OOOOOPS, I am thinking generators.
    Military wives deserve the Purple Heart Medal. They are wounded every time their Soldier goes off to protect our freedom!

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