FMC-Article 348

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ken44

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Austin, TX
I was not pleased to find that an electrical project I was in charge of had a 50' run of FMC from the junction box to the wall receptacle where the copier was going to be plugged in but in reading article 348, It only states the following as being limited to 6' in length:

(1) In wet locations
Listed flexible metal conduit (FMC) is no longer permitted for use in wet locations. Also, for this application, the conductors must be suitable for wet locations. Listed FMC 1/2 in. and larger may be installed in unlimited lengths, provided an equipment grounding conductor is installed with the circuit conductors. See 250.118(5) as well as 348.60 for specific requirements related to the use of FMC as an equipment grounding conductor.
(2) In hoistways, other than as permitted in 620.21(A)(1)
(3) In storage battery rooms
(4) In any hazardous (classified) location except as permitted by other articles in this Code
(5) Where exposed to materials having a deteriorating effect on the installed conductors, such as oil or gasoline
(6) Underground or embedded in poured concrete or aggregate
(7) Where subject to physical damage

Can I please get some input, even though the NEC may permit a 50' run, it does not seem to me that this is in keeping with "neat and workman like", I did not figure that the electricians need thousands of dollars worth of nice portable tools to run FMC all over the place.
 
I don't see why you would think a 50' run of FMC wouldn't qualify as neat and workmanlike. It is definely allowed by the NEC and I don't know any inspectors or electricians that would say it wasn't neat or workmanlike, unless the run wasn't supported properly or there was some other problem. I frequently use FMC and it is common in my area and don't see anything wrong with a 50' run.
 
I have been told that when runs of FMC get to be around 100', the FMC starts getting hot from an effect called the "transformer effect". Has anyone else heard of this?
 
ken44 said:
I have been told that when runs of FMC get to be around 100', the FMC starts getting hot from an effect called the "transformer effect". Has anyone else heard of this?
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Nope - haven't heard that one... But I assume this same 'effect' would also affect EMT... Since both/all conductors of the circuit should be contained in the conduit they should cancel out the induced electro-magnetic & heating effects that would be present if individual conductors were run alone.

But anyway -
it does not seem to me that this is in keeping with "neat and workman like", I did not figure that the electricians need thousands of dollars worth of nice portable tools to run FMC all over the place.
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Sounds liked there is an electrical design conflict between you and your guys - since there is no code violation if done correctly.
 
Neat and Workman like is in the eye of the beholder.

Roger
 
ken44 said:
Can I please get some input, even though the NEC may permit a 50' run, it does not seem to me that this is in keeping with "neat and workman like", I did not figure that the electricians need thousands of dollars worth of nice portable tools to run FMC all over the place.
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:confused::confused: Where did you get the idea the elect. needed thousands of dollars worth of tools to run fmc?
 
ceb58 said:
:confused::confused: Where did you get the idea the elect. needed thousands of dollars worth of tools to run fmc?
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I think that was just tool envy - and he didn't like that some guys in the field took it upon themselves to do something that was unspecified - and may have saved a dime or so in labor doing it.
 
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