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Discussion Starter · #1 ·
I took over a remodel and found the person before me used 3/8 FMC as a wiring method.
They kinda used it as MC in some places. With that, I mean that they have more than 360 deg of bends.
I have never concealed 3/8 and considered using it as a "raceway" with the same limitations as EMT would have.

Question:
Can 3/8 FMC be concealed with the 360 deg limitations and used like this or does it have to come out and be replaced with MC?
 

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jrannis said:
I took over a remodel and found the person before me used 3/8 FMC as a wiring method.
They kinda used it as MC in some places. With that, I mean that they have more than 360 deg of bends.
I have never concealed 3/8 and considered using it as a "raceway" with the same limitations as EMT would have.

Question:
Can 3/8 FMC be concealed with the 360 deg limitations and used like this or does it have to come out and be replaced with MC?
Chances are , you've already got 3 to 4 # 14's , 12's , or 10's in the flex now , which doesn't lend itself to adding new circuits down the line anyway . If it were 1/2" or 3/4" , you could pretty easily change things down the line , if you wanted . I wouldn't rip anything out unless the AHJ made me . Most of the inspectors I see around here would think it was mc anyway and not think twice about it .
 

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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)

(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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HackWork said:
I've used it to sleeve romex for protection. I assume 348.20 doesn't apply if used as a sleeve. But now that I think about it, 3/8" is probably too small for the romex.
I think it is too small for romex. The table in 348.22 only lists single conductors.
 

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The only place I ever used 3/8" flex was controls for HVAC. It would have never crossed my mind to use it on anything more than motors & control devices.

My old boss used to tell us that a roll of 3/8" flex was more expensive than 1/2". I don't know if thats true or not, but we tried to use 1/2" as much as we could.
 

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Discussion Starter · #8 ·
Complete fail. :laughing:

the last guy stripped Romeo and installed in in the 3/8" FMC. this also included the bare ground.
Inspector called it out.
I thought green or bare was acceptable, not that it mattered.

He wants arc faults in the existing panel.
 

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Complete fail. :laughing:

the last guy stripped Romeo and installed in in the 3/8" FMC. this also included the bare ground.
Inspector called it out.
I thought green or bare was acceptable, not that it mattered.

He wants arc faults in the existing panel.
The issue is not with the insulated vs bare ground wire. The issue is NEC 310.11.
The conductors inside romex are not marked thus they can not be stripped out of the NM jacket and used as separate conductors.
 
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