Flex Conduit as ground

Discussion in 'Electrical Forum discussion & Blog' started by M3, Feb 24, 2009.

  1. M3

    M3 Member

    Messages:
    42
    Location:
    Minnesota
    I have a 1970's home that has all aluminum wiring running through flex conduit, and the flex back then "was and still is" the grounding conductor to the main panel. I know the aluminum is "ok" if it is tied in properly with the use of proper outlets and switches... but I've noticed none of the outlets have grounding ties, and many of them are not even in contact with metal junction boxes (except the screws), thus cutting down on the grounding capability. I've also seen that new flex conduit is now marked "ok for grounding in uses of 6' or less.

    My question is: Has the material changed over the years making it only good as a ground for up to 6'?

    Secondly: What if I want to change out the aluminum wiring (potential buyers are leary of it); does the NEC state that a grounding wire has to be pulled through the system or can I just pull copper neutral and hot wires and tie in ground leads to the metal boxes?

    Any information would be helpful.
  2. drick

    drick In the Trades

    Messages:
    392
    Flex conduit? I assume you mean MC or BX metal clad cable. If this is the case it is not conduit and you will not be pulling out the old wiring through the cable as this is not possible. You are looking at a total rewire.

    And yes the you have to run a ground wire UNLESS the MC has a grounding strip the length of the cable. In that case you can use the MC cable as the the ground.

    -rick
  3. M3

    M3 Member

    Messages:
    42
    Location:
    Minnesota
    YES, it is flex conduit. See http://www.alliedtube.com/electrical-raceways/conduit/flexible-metal-conduit-ew.asp It was and is commonly used; it just doesn't have the wire included running through it.

    I know in a new construction (if it were to be used) the ground should be there. I'm just wondering why the change in not allowing the use of it as a ground, as it was years ago. And if any "grandfathering" applies. My guess is no, but I'm not sure.
  4. Alectrician

    Alectrician DIY Senior Member

    Messages:
    689
    Flex, longer than 6' has not been approved for grounding since I've been in the trade (73)

    Also, individual AL conductors are very rare around here.
  5. drick

    drick In the Trades

    Messages:
    392
    MC looks exactly like that, but includes the conductors. Your there, I'm not but I've never seen a house wired with flex conduit. Why would you when you can buy the same thing with conductors included? Either way I doubt you'll be able to pull out the existing conductors.

    Generally, as a rule, if you touch something you need to bring it up to existing codes, so no grandfathering.

    Years ago grounding of electrical devices was not required. Some of the early romex did not have a grounding conductor. As I mentioned earlier I think a former homeowner swapped out the ungrounded receptacles for grounded ones. That doesn't mean it was ever a permitted grounding method.

    -rick
    Last edited: Feb 25, 2009
  6. M3

    M3 Member

    Messages:
    42
    Location:
    Minnesota
    Maybe MN didn't adopt the newest NEC code back in 73 because my house was built in 73 and it's all powered by aluminum conductors encased in flexible aluminum conduit without any grounding wires. Every circuit is 12 gauge aluminum wire and there are some 20 amp circuits on it, which is a no, no...

    It really gets confusing looking back in time at the year of codes were issued, especially when individual states can or cannot adopt them.
    Last edited: Feb 26, 2009
  7. rgsgww

    rgsgww New Member

    Messages:
    53
    Location:
    Ia
    If there is paper or plastic in this "conduit" than I can assure you it is not conduit.

    It might be possible, but not easy.
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,265
    Location:
    Cave Creek, Arizona
    conduit

    I cannot imagine why someone would go to the expense of using flexible conduit, and then cheapen it by using aluminum wire. All you can do is try to pull a wire and see if it moves. If it does then you can use one of the old wires to pull the new ones in, and once you do that, why would you then go "cheap" and not pull a ground wire?
Similar Threads: Flex Conduit
Forum Title Date
Electrical Forum discussion & Blog ground wire in flexible steel conduit - and a de-rating question Jul 26, 2013
Electrical Forum discussion & Blog Flexible Conduit? Sep 17, 2010
Electrical Forum discussion & Blog Long flex metal conduit instead of rigid pipe? Jun 17, 2008
Electrical Forum discussion & Blog flexible metal conduit/greenfield Mar 21, 2008
Electrical Forum discussion & Blog Straps for 1/2" Flex Jul 30, 2007

Share This Page