Feeder cables wiring installation through block or concrete walls

[arscaribe]

I would like to know if is permitted by NEC to install feeder cables (let say a run of four single conductors THHN) from a MDP (main distribution panel) through the walls of a commercial building to a main disconnect switch on an equipment. The installation of the conductors are without any type of conduit (metallic or non-metallic) just the cables directly in contact with the wall concret or blocks.

Thank you

 

[chris kennedy]

No, see 300.3(A).

 

[arscaribe]

Feeder cables wiring installation through block or concrete walls

No, see 300.3(A).

Thank you!!

 

[petersonra]

I am inclined to agree, but whether it is a hazard or not is something else. It seems like a fairly common practice to chop a hole in a concrete wall and feed conductors through between two enclosures mounted on either side.

 

[GoldDigger]

I am inclined to agree, but whether it is a hazard or not is something else. It seems like a fairly common practice to chop a hole in a concrete wall and feed conductors through between two enclosures mounted on either side.

If the conductors are supported clear of the concrete by the bushings on the two enclosures, that is very different from laying a longer run of conductors into place supported by the concrete or able to rub against the concrete. Although an inspector still may not allow even that.

 

[petersonra]

If the conductors are supported clear of the concrete by the bushings on the two enclosures, that is very different from laying a longer run of conductors into place supported by the concrete or able to rub against the concrete. Although an inspector still may not allow even that.

why is it different? it is still not a chapter 3 wiring method.

 

[GoldDigger]

why is it different? it is still not a chapter 3 wiring method.

It is no different in terms of the applicable code, just in the underlying safety hazard that led to that code requirement being made.

I was trying to address the "fairly common practice", even though it is not code compliant.

 

[PowerSupportElec]

It seems like a fairly common practice to chop a hole in a concrete wall and feed conductors through between two enclosures mounted on either side.

I've never seen that. Usually they will either stub conduits or install a piece of trough between the two enclosures.

 

[petersonra]

I've never seen that. Usually they will either stub conduits or install a piece of trough between the two enclosures.

I can't say I recall seeing a trough in such a case, but I have seen a fair number of conduits of various kinds, along with just holes the wires run through.

I just do not see it as that much of a hazard that I would worry about it all that much despite not being code.

I see EMT and various kinds of flex that have come loose pretty regularly that bother me more.

 

[PowerSupportElec]

I can't say I recall seeing a trough in such a case, but I have seen a fair number of conduits of various kinds, along with just holes the wires run through.

I just do not see it as that much of a hazard that I would worry about it all that much despite not being code.

I see EMT and various kinds of flex that have come loose pretty regularly that bother me more.

I've seen people run loose #14 THHN out of a receptacle box behing their stove up through the wall into the JB on the vent fan above. This is ok too? It's only a few amps in those conductors, not like a feeder. And it's only drywall that the conductors are running through, not abrasive concrete block.


:thumbsup:

 

[petersonra]

I've seen people run loose #14 THHN out of a receptacle box behing their stove up through the wall into the JB on the vent fan above. This is ok too? It's only a few amps in those conductors, not like a feeder. And it's only drywall that the conductors are running through, not abrasive concrete block.


:thumbsup:

There is a difference between "not to code" and "hazardous".

I have seen stuff wired in 2 wire lamp cord. Not to code and no EGC so actually hazardous, where as the same thing wired in 2c/g SO is perfectly safe but not to code either.

I have gotten to the point where I worry less about things that do not actually present some hazard than actual hazards in existing work.

 

[PowerSupportElec]

There is a difference between "not to code" and "hazardous".

I have seen stuff wired in 2 wire lamp cord. Not to code and no EGC so actually hazardous, where as the same thing wired in 2c/g SO is perfectly safe but not to code either.

I have gotten to the point where I worry less about things that do not actually present some hazard than actual hazards in existing work.

I agree with you on that.

But feeders running through a block wall like described is not something I would consider safe or professionally installed. I think it's hack work, and IMO it's more dangerous than the THHN running in a wall like I described above, which most people would also consider hack work.