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Flexibility is required #99656
08/25/06 01:42 PM
08/25/06 01:42 PM
G
George Little  Offline OP
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
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?


George Little
2017 / 2014 NEC & Related Books and Study Guides
Re: Flexibility is required #99657
08/26/06 06:42 AM
08/26/06 06:42 AM
J
jwhite  Offline
Member
Joined: Dec 2005
Posts: 64
Trenton, NC, USA
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
08/26/06 08:12 AM
08/26/06 08:12 AM
R
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
George,
Does the FMC have supports within 12" of each termination?
Don


Don(resqcapt19)
Re: Flexibility is required #99659
08/26/06 08:38 AM
08/26/06 08:38 AM
G
George Little  Offline OP
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
Don- Let's say that it does have secure support within 12" of the conduit terminations. What triggers your question?


George Little
Re: Flexibility is required #99660
08/26/06 02:09 PM
08/26/06 02:09 PM
S
SolarPowered  Offline
Member
Joined: Jul 2004
Posts: 625
Palo Alto, CA, USA
Code aside, I've seen way too many conduit connectors hanging by the wires to trust any conduit system as a grounding path, with the exception of threaded RMC or IMC.

Re: Flexibility is required #99661
08/26/06 07:14 PM
08/26/06 07:14 PM
R
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
George,
Quote
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


Don(resqcapt19)
Re: Flexibility is required #99662
08/26/06 08:09 PM
08/26/06 08:09 PM
G
George Little  Offline OP
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
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.


George Little
Re: Flexibility is required #99663
08/28/06 12:20 AM
08/28/06 12:20 AM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,298
Estero,Fl,usa
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.


Greg Fretwell
Re: Flexibility is required #99664
08/28/06 01:18 PM
08/28/06 01:18 PM
R
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
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


Don(resqcapt19)
Re: Flexibility is required #99665
08/28/06 04:48 PM
08/28/06 04:48 PM
G
George Little  Offline OP
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
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.


George Little
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