Article 348.30(A)(ex.4) & 314.23(E) & exception

[Sandlapper]

Gentlemen,

Is it permissable to transition directly to FMC or for that matter LFMC utilizing a properly supported condulet fitting? Have recently run into a project where it was suggested that a short nipple was required to make this transition. Is a T fitting consider properly supported when it is supported on two sides, or an LB on one side as per 314.23(E)?

Feel free to ask a few questions as I know this is probably not enough info to get to the truth of the matter. I'm usually as clear as mud anyway.

 

[Smart $]

Gentlemen,

Is it permissable to transition directly to FMC or for that matter LFMC utilizing a properly supported condulet fitting? Have recently run into a project where it was suggested that a short nipple was required to make this transition. Is a T fitting consider properly supported when it is supported on two sides, or an LB on one side as per 314.23(E)?

Feel free to ask a few questions as I know this is probably not enough info to get to the truth of the matter. I'm usually as clear as mud anyway.

FWIW, I've never heard of a short nipple being required to make the transition, but...

There are those that oppose using a connector in the threaded hub of a conduit body (i.e. not made for this purpose), but you have the same situation if you use a nipple, coupling, then connector. Made-for-the-purpose transition fittings are usually stocked for EMT to FMC, but other types are not (that I'm aware of).

In general, I believe you are allowed the installtions you ask about... but there will always be controversy over the specifics...

 

[Sandlapper]

Smart $

Can you explain the exception to 314.23 (E)?

 

[don_resqcapt19]

I don't think that there is any issue with a single conduit supporting a conduit body of the same trade size. The real issue would be the required supports for the LFMC or the FMC. In general the flex terminations are not supports.

 

[Smart $]

Smart $

Can you explain the exception to 314.23 (E)?

The exception basically removes the restriction of size in excess of 100 in? imposed by the general requirement of 314.23(E) for enclosures under the scope of Article 314.

Without the exception, you could not raceway support (guessing here...) 3" and larger conduit bodies.

 

[Smart $]

I don't think that there is any issue with a single conduit supporting a conduit body of the same trade size. The real issue would be the required supports for the LFMC or the FMC. In general the flex terminations are not supports.

The general requirement does not prohibit the use of a conduit body larger than the largest conduit when the conduit body is 100 in? or less. It is only under the exception does the trade size of the conduit body and largest conduit have to match.

 

[Sandlapper]

Now with you Gentlemens' indulgence, I would like to explore how 348.30 (A) Exception 4 comes into play. Would a conduit body, such as a Tee or a cross, not more than 100 cubic inches in size, supported by at least two conduits as per 314.23(E) be considered as "the last point where the raceway is securely fastened" , and therefore allow a maximum of 6 feet of unsupported FMC for connections to lights or equipment.

 

[Smart $]

Now with you Gentlemens' indulgence, I would like to explore how 348.30 (A) Exception 4 comes into play. Would a conduit body, such as a Tee or a cross, not more than 100 cubic inches in size, supported by at least two conduits as per 314.23(E) be considered as "the last point where the raceway is securely fastened" , and therefore allow a maximum of 6 feet of unsupported FMC for connections to lights or equipment.

No. A conduit body establishes a raceway termination for all associated conduit runs... i.e. the FMC is a separate raceway. An unsupported 6' length of FMC is permitted under the conditons of the exception.

 

[Sandlapper]

Smart $,

So the "raceway" being referred to in the exception is the FMC. Is the exception implying that as long as the FMC was strapped and supported in accordance with 348.30, from that final support in an accessible ceiling, the FMC can be unsupported for a maximum of six feet? For example we could have a total run of 20 feet of FMC with only 14 feet suppported as per 348.30

 

[Smart $]

Smart $,

So the "raceway" being referred to in the exception is the FMC. Is the exception implying that as long as the FMC was strapped and supported in accordance with 348.30, from that final support in an accessible ceiling, the FMC can be unsupported for a maximum of six feet? For example we could have a total run of 20 feet of FMC with only 14 feet suppported as per 348.30

As long as the unsupported section is [measured] at the luminaire end of the FMC.

 

[Sandlapper]

Now, according to 348.30 exception 2, varying unsupported lengths of FMC are allowed, based on the (FMC) raceway size. Now since FMC fittings are not a source of raceway support, does that imply that the point to begin the measure of the unsupported length would be the last point on the raceway, or conduit body that would be considered supported by the Code?

Thanks for allowing me to ask a thousand questions. I'm just a kid at heart, especially at this time of year!

 

[Smart $]

Now, according to 348.30 exception 2, varying unsupported lengths of FMC are allowed, based on the (FMC) raceway size. Now since FMC fittings are not a source of raceway support, does that imply that the point to begin the measure of the unsupported length would be the last point on the raceway, or conduit body that would be considered supported by the Code?

Exception 2 is poorly worded in the sense the general requirement already permits unsupported, unsecured lengths up to 4.5'. So other than the 5' allowance of 2.5" and larger, the exception rescinds the securely fastened within 12" of termination requirement for all sizes, in the area where flexibility is necessary.