Article 348.60 requires an equipment grounding conductor be installed "where flexibility is required" for the installation. I know that FMC is installed mainly for the ease of installation and not because flexibility is needed. If we need flexibility due to vibration is one thing but most time it's just easier to use "greenfield". The State of Michigan requires an EGC in all flexible wiring methods regardless. The only exception is FMT. What do other States require?
NC has not exceptions to the national code on this issue.
I on the other hand mostly do work under government specs. A ground wire is required almost everywhere. The only place you might not see one is between a tx and the first disconnect on a service enterance.
Re: Flexibility is required#99658 08/26/0607:12 AM08/26/0607:12 AM
Let's say that it does have secure support within 12" of the conduit terminations. What triggers your question?
In most installations of the type that you are talking about there is no support and the only way that you can install the raceway without such support is where flexiblity is required. Then you must have a bonding jumper. I think that even the normal motor vibrations are enough to trigger the bonding jumper requirement even if there is support within the 12"...it is just very clear that the bonding jumper is required when there is no installed support. Don
Re: Flexibility is required#99662 08/26/0607:09 PM08/26/0607:09 PM
Don- Fixture whips normally don't have any support other than the fittings and the FMC is installed in these cases for the ease of installation and to allow for the repositioning of fixtures if there is an office furniture adjustment etc. In these cases it's not a case of vibration and in Michigan we use an EGC for installation of this sort. Conduit length is not an issue nor is the ampacity of the circuit. I think this is an excellent requirement. Now with the cost of copper, I see this as a shortcut I need to watch for.
Re: Flexibility is required#99663 08/27/0611:20 PM08/27/0611:20 PM
I saw lots of FMC in the computer biz when they decided SO cord was not appropriate under the floor. The problem is I never saw a FMC connector that could actually hold FMC if there was no other support. It is clear they expect it to be secured within a foot of the connector. It was very common to pull up a tile and see a 60a Russell Stoll hanging on the THHN. You were sure happy to see a green wire in there.
Re: Flexibility is required#99664 08/28/0612:18 PM08/28/0612:18 PM
George, There are 4 exceptions for not having a support within 12" of the FMC termination. Two have to do with taps or whips to light fixtures, one with a "fished" installation and the last for where flexibility is required. In the case of motors or transformers the only one that would apply is flexibility, so in cases like that if there is no support within 12" a bonding jumper is required. Don
Re: Flexibility is required#99665 08/28/0603:48 PM08/28/0603:48 PM
Don- You might have miss read me, I agree with your interpertation and we understand it that way here in Michigan. HOWEVER the State of Michigan has an amendment to the NEC that says we need a EGC in ALL flexible wiring methods. And I think that is a good amendment. I think others who commented on this post agree. I merely wanted to know what other state were doing.