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electrical grounding question

cutter Member Posts: 282
I am changing out my Wilo circulating pumps to Grundfos. The grundfos pumps Need flexible conduit from the pump to a box. What I am wanting to know is can I run a bare ground through the flexible conduit or do I need green coated #14 wire. Flexible conduit in my part of the world is called greenfield or was called that, maybe still is.


    EBEBRATT-Ed Member Posts: 10,355
    It still is "Greenfield" technically it's "flexible metallic conduit" according to the electrical code. The ground can be bare or green, either way is ok
  • cutter
    cutter Member Posts: 282
    I was thinking the bare would be ok but wanted to make sure, Thanks
  • mattmia2
    mattmia2 Member Posts: 3,991
    Depending on jurisdiction, sometimes the ground can be the flex itself if it is under a certain length. Michigan is not one of those jurisdictions.
  • pecmsg
    pecmsg Member Posts: 2,345
    Mechanical grounds are no longer allowed. 
  • ChrisJ
    ChrisJ Member Posts: 11,978
    edited August 24
    pecmsg said:

    Mechanical grounds are no longer allowed. 

    The NEC no longer allows the use of conduit as a ground?
    I thought EMT etc was still acceptable.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
    JUGHNE Member Posts: 8,972
    I haven't looked at the newest code book.
    I believe metallic raceway is still allowed as a grounding path.
    Personally I always run a green ground wire.

    Flex conduit, FMC (Greenfield), might qualify for grounding under 6' in length.

    Depending upon AHJ, again having seen flex connectors pulled apart and even loose locknuts on EMT, I personally do not trust the flex or EMT for safe grounding.

    In electrical trade magazines I used to read of challenges to the AHJ who wanted a green wire in the flex, as always there are exceptions in the "Book of Exceptions".
    AKA the NEC book.

    IMO, it was easier to just add the 6-10' of green wire than butt heads with your inspector who will remember you if you win the pi$$ing contest and his boss overrides him.
    Save your ammo for the big battles.
    EBEBRATT-Ed Member Posts: 10,355
    Mechanical grounds are still allowed

    EMT, rigid conduit, intermediate metal conduit can be used for grounding. BX (type ac cable) doesn't have a ground except for the armor and the aluminum strip so how can mechanical grounds be not allowed?

    Greenfield (flexible metallic conduit) can be used for a ground only if the circuit is 20 amps or less and the fittings are listed for grounding (most are not)

    Metallic sealtight can be used for a ground but only under certain circumstances .

    That being said it is always better to pull a ground wire bare or green

    and in this day and age most electricians do just that.

    That being said there are plenty of buildings wired with no ground wire....just the pipe. If installed properly it's not an issue.

    In fact some studies show the pipe being a better ground than a wire which surprised me.