Flexible metal conduit length?

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sparks27

Member
Location
Portland, Oregon
I was wondering when did the 6ft. length limit go into effect? I have a multi family dwelling run completly in steel flex. Some runs are 20 something ft. in length. I don't see a specific code for aluminum flex? bldgs. are 1960s era. thanks Brian,
 
John Valdes

John Valdes

Senior Member
Location
SC.
Occupation
Retired Electrician
I have been hearing that myth for almost 35 years. When I was an apprentice we had some fixture whips that were about 10' long. I asked the JW how we could do that and he straightened me out right there and then. I still hear it today on occasion.
 
tkb

tkb

Senior Member
Location
MA
The restriction is only for smaller than 1/2".

348.20 Size.
(A) Minimum. FMC less than metric designator 16 (trade size 1/2) shall not be used unless permitted in 348.20(A)(1) through (A)(5) for metric designator 12 (trade size 3/8).
(1) For enclosing the leads of motors as permitted in 430.245(B)
(2) In lengths not in excess of 1.8 m (6 ft) for any of the following uses:
a. For utilization equipment
b. As part of a listed assembly
c. For tap connections to luminaires as permitted in 410.117(C)
Section 348.20(A)(2) makes it clear that 3/8-in. flexible metal conduit is permitted to be used as the manufactured or field-installed metal raceway (11/2 ft to 6 ft in length) to enclose tap conductors between the outlet box and the terminal housing of recessed luminaires. Flexible metal conduit is also permitted to be used as a 6-ft luminaire whip from an outlet box to a luminaire.
Section 604.6(A) permits a smaller minimum size for manufactured wiring systems because the conductors are not as prone to physical damage when assembled under factory-controlled conditions.
(3) For manufactured wiring systems as permitted in 604.6(A)
(4) In hoistways as permitted in 620.21(A)(1)
(5) As part of a listed assembly to connect wired luminaire sections as permitted in 410.137(C)
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jetlag

Senior Member
Location
Eatonton, Georgia
sparks27 said:
I was wondering when did the 6ft. length limit go into effect? I have a multi family dwelling run completly in steel flex. Some runs are 20 something ft. in length. I don't see a specific code for aluminum flex? bldgs. are 1960s era. thanks Brian,
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If im not mistaken there is a 6ft limit that can be unsupported to a drop ceiling light fixture.
 
cowboyjwc

cowboyjwc

Moderator
Staff member
Location
Simi Valley, CA
sparks27 said:
You Sir are Correct, Nec 05' 250.118 (5-C) combined length not to exceed 6ft. also (B) says on cirs. not over 20A. So longer than 6ft. and or cir conductors over 20a. must have egc ?
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I would think that if you used Alflex or any other listed flexes, and went by their listing, you would not need to run an egc.
 
cowboyjwc

cowboyjwc

Moderator
Staff member
Location
Simi Valley, CA
Dennis Alwon said:
Why not? Doesn't 250.118 say you must if the flex is over 6'.
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Because I missed a code change.:roll:

In the 2002 there was no mention of 250.118 in article 348.60 and the tag on Alflex (I thought I had one here, but I don't) said that it was listed for grounding in lengths of 100' or 10 boxes or something to that effect though that may be an approval from the City of Los Angeles testing labs, which we accept.
 
kwired

kwired

Electron manager
Location
NE Nebraska
jetlag said:
If im not mistaken there is a 6ft limit that can be unsupported to a drop ceiling light fixture.
Click to expand...

That is an exception for a specific condition to the support requirements of 348.30

You can have longer lengths than that but must be supported according to 348.30.

It is a support requirement not a limit on length of raceway.

Other length restrictions are for using it as an equipment grounding conductor and not a limit on length of raceway - if longer raceway is desired you must install an equipment grounding conductor.
 
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