Flexible metallic conduit above false ceiling

[TMMB]

I have an issue regarding the flexible metallic conduit as follows:

1-What is the maximum permitted length of the flexible metallic conduit FMC above false ceiling as per NEC?
2- There is coaxial cable for GSM system, can we use the FMC as main raceway for long length above false ceiling or there is limited length can not exceed it ?


Please advise

 

[infinity]

In general for FMC there is no length limit if 1/2" or larger and properly supported.

 

[Dennis Alwon]

One thing most people don't think about is that fmc is limited to 360? just as emt. 348.24

 

[Dennis Alwon]

In general for FMC there is no length limit if 1/2" or larger and properly supported.

To add to this an equipment grounding conductor is needed if the conductors are protected over 20 amps and more than 6'

 

[TMMB]

but as per NEC 348.3 A as follows:

Exception No. 3]:Lengths not exceeding 1.8 m (6 ft) from a
luminaire terminal connection for tap connections to luminaires
as permitted in 410.117(C).

Exception No. 4": Lengths not exceeding 1.8 m (6 ft) from
the last point where the raceway is securely fastened for
connections within an accessible ceiling to luminaire(s) or
other equipment

it is limited to 1.8 m , or no limited length?

 

[roger]

The exceptions are pertaining to 3/8" FMC.

Roger

 

[Little Bill]

but as per NEC 348.3 A as follows:

Exception No. 3]:Lengths not exceeding 1.8 m (6 ft) from a
luminaire terminal connection for tap connections to luminaires
as permitted in 410.117(C).

Exception No. 4": Lengths not exceeding 1.8 m (6 ft) from
the last point where the raceway is securely fastened for
connections within an accessible ceiling to luminaire(s) or
other equipment

it is limited to 1.8 m , or no limited length?

That should be 348.30

The exceptions are pertaining to 3/8" FMC.

Roger

No, the exceptions are for securing and supporting.

It is saying that the maximum length that can be unsupported if flexibility is needed is the lengths that are listed in the exceptions according to the FMC size.

But to the OP's question, there is no length limit if properly supported/secured.

 

[roger]

That should be 348.30



No, the exceptions are for securing and supporting.

It is saying that the maximum length that can be unsupported if flexibility is needed is the lengths that are listed in the exceptions according to the FMC size.

But to the OP's question, there is no length limit if properly supported/secured.

I guess I should have looked, I was replying from memory and thinking of the exceptions to 348.20(A)


Roger

 

[Little Bill]

I guess I should have looked, I was replying from memory and thinking of the exceptions to 348.20(A)


Roger

So, am I still on your Christmas list?

 

[don_resqcapt19]

One thing most people don't think about is that fmc is limited to 360? just as emt. 348.24

And you need to include all of the sags between supports when you count the 360?.

 

[Dennis Alwon]

And you need to include all of the sags between supports when you count the 360?.

I bet that does not happen. :happyno::happyno: I can't remember the last time I used flex.

 

[roger]

So, am I still on your Christmas list?

Of course.

Roger