Conduit in ductwork?? 4

[klubie]

Is it a code violation to route conduit through ductwork?

 

[rbulsara]

Did you ask your mechanical engineer? or checked mechanical codes?

Rafiq Bulsara

http://www.srengineersct.com

 

[klubie]

mechanical engineer says it is not a code violation in his return duct.

 

[Overvoltage]

I'd start with 300.21...

 

[rbulsara]

I am not the one to stop you from shooting in the foot either. You are free to ignore my response.



Rafiq Bulsara

http://www.srengineersct.com

 

[dpc]

See 300.22. Anything not allowed there is prohibited.

 

[EEJaime]

klubie,
Your mechanical is correct. Per NEC 300.22(B), you can run conduit in environmental air ducts or plenums as long as it complies with the list of items this code provision allows. That means basically that it needs to have an exterior metal finish, MC, MI cable, EMT, flexible metallic conduit-(up to 4'in length), IMC are all ok. Just don't use anything with a non-metallic covering.
Regards,
EEJaime

 

[waross]

It has to do with developing and conducting noxious gases to other areas of a building through the duct work in the event of a fire or a destructive fault in a cable.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[rbulsara]

Air plenums (eg. above ceiling spaces) are not same as metal ductwork.

Check with local AHJ.

Rafiq Bulsara

http://www.srengineersct.com

 

[alehman]

I see EMT and FMC in big air handling equipment and associated ductwork frequently. As Rafiq said, check with the AHJ.

Alan
----
"It’s always fun to do the impossible." - Walt Disney

 

[EEJaime]

The title of NEC 300.22 is "Wiring in Ducts,Plenums, and Other Air-Handling Spaces" I think that would include metal ductwork.

 

[raithrovers1]

Sometimes we all need help in our line of work no matter how experienced we are.
I find it sad that some people are using this forum to make people feel inferior compared to themselves by making comments that are not condusive to helping the person who has asked the question.
I must congratulate the majority of users for giving positive responses to all questions no matter the complexity and long may it continue!

UPS engineer

http://www.powerups.co.uk

 

[PHovnanian]

Another part of 300.22(B):
"Equipment and devices shall be permitted within such ducts or plenum chambers only if necessary for their direct action upon, or sensing of, the contained air."

The AHJ may interpret this as only permitting conduit within ductwork that is directly associated with that duct's air handling, sensing or other associated functions.

 

[DRWeig]

I'm in with PHovnanian -- I'd avoid the duct unless it's wiring associated as stated in 300.22(B). If so, conduits as EEJaime said.

Good on ya!

Goober Dave

 

[EEJaime]

Phovnanian,
I believe that passage in 300.22(B) is specifically referencing the equipment and devices which are allowed to be connected using the 1.2m(4ft) of flexible metal conduit. The sentences prior to it read:

"Flexible Metal conduit shall be permitted in lengths not exceed 1.2 m (4ft), to connect physically adjustable equipment and devices permitted to be in these ducts and plenum chambers. The connectors used with flexible metal conduit shall effectively close any openings in the connection. Equipment and devices shall be permitted ...."

It does not limit conduit at all except specifically flexible metal conduit connecting said equipment and devices.

Regards,
EEJaime