LFMC in plenum alternative

[brackers]

I'm new to the forum and in real need of some help related to plenum rated liquid tight wiring. I'm trying to determine if there is a suitable alternative to LFMC that is plenum rated?

It seems that the code committee didn't take into consideration situations where a plenum, such as an air handler, is required to be constructed for wash down duty and the wiring needs to be liquid tight.

Can anyone help on this?

 

[jumper]

Maybe I am confused, but it seems alternatives are available. I believe some can be installed in wet locations with the right fittings.

300.22(B)

(B) Ducts Specifically Fabricated for Environmental Air.
Only wiring methods consisting of Type MI cable, Type
MC cable employing a smooth or corrugated impervious
metal sheath without an overall nonmetallic covering, electrical
metallic tubing, flexible metallic tubing, intermediate
metal conduit, or rigid metal conduit without an overall
nonmetallic covering shall be installed in ducts specifically
fabricated to transport environmental air.

 

[brackers]

Maybe I wasn't clear, I'm referring to situations where you would typically use FMC or LFMC, such as at a motor junction box. I'm not aware of any liquid tight flexible conduit products that are constructed "without an overall nonmetallic covering".

 

[Gregg Harris]

Maybe I wasn't clear, I'm referring to situations where you would typically use FMC or LFMC, such as at a motor junction box. I'm not aware of any liquid tight flexible conduit products that are constructed "without an overall nonmetallic covering".

There is non that I am aware of other than pvc covering and that does not comply. I have yet to find any product with the verbiage used. What does this actually refer to, impervious to what? The purpose would to prevent smoke being emitted into the air, but standard AC cable I do not believe it to be impervious

(B) Ducts Specifically Fabricated for Environmental Air. Only wiring methods consisting of Type MI cable, Type MC cable employing a smooth or corrugated impervious metal sheath without an overall nonmetallic covering, electrical metallic tubing, flexible metallic tubing, intermediate metal conduit, or rigid metal conduit without an overall nonmetallic covering shall be installed in ducts specifically fabricated to transport environmental air. Flexible metal conduit shall be permitted, in lengths not to exceed 1.2 m (4 ft), to connect physically adjustable equipment and devices permitted to be in these fabricated ducts. The connectors used with flexible metal conduit shall effectively close any openings in the connection. Equipment and devices shall be permitted within such ducts only if necessary for the direct action upon, or sensing of, the contained air. Where equipment or devices are installed and illumination is necessary to facilitate maintenance and repair, enclosed gasketed-type luminaires shall be permitted.

 

[don_resqcapt19]

You can use flexible metallic tubing (FMT) for that application. It is the required flexible wiring method for 300.22(C) spaces in the Chicago area.

360.2 Definition. Flexible Metallic Tubing (FMT). A raceway that is circular in cross section, flexible, metallic, and liquidtight without
a nonmetallic jacket.

 

[Gregg Harris]

You can use flexible metallic tubing (FMT) for that application. It is the required flexible wiring method for 300.22(C) spaces in the Chicago area.

Don AC and MC cable is also listed for 300.22(C) Other Space Used for Environmental Air

but not for 300.22(B) Ducts or Plenums Used For Environmental Air

 

[don_resqcapt19]

Don AC and MC cable is also listed for 300.22(C) Other Space Used for Environmental Air

but not for 300.22(B) Ducts or Plenums Used For Environmental Air

FMT is suitable for both (B) and (C) spaces. The question was an alternative to LFMC. I don't see any any cabling wiring as an alternative to a conduit. Not because they are not suitable, but because there may be an issue with the size and number of conductors needed for the application that would preclude the use of a cable other than a special order cable.

If the comment is directed at the use of AC or MC in the Chicago area, I am not sure what the current code is there, but in the past the only flexible wiring method that was permitted in 300.22(C) spaces was FMT.

 

[Smart $]

FMT is suitable for both (B) and (C) spaces. The question was an alternative to LFMC. I don't see any any cabling wiring as an alternative to a conduit. Not because they are not suitable, but because there may be an issue with the size and number of conductors needed for the application that would preclude the use of a cable other than a special order cable.

If the comment is directed at the use of AC or MC in the Chicago area, I am not sure what the current code is there, but in the past the only flexible wiring method that was permitted in 300.22(C) spaces was FMT.

Here's a product link:

http://www.garvinindustries.com/lig...num-flexible-metal-tubing-connectors-no-wires