NMC question

[kurt]

I never see romex; all EMT in my world.

Did a summer home job over in Michigan this morning. You're not allowed to secure the stuff to a furnace like, are you?

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[Marc]

It isn't supposed to be there in the first place because it can be damaged too easily. A plug/cord or type SO cable would be ok.

Marc

[kurt]

thanx

[Richard Moore]

Although this is NM country, I don't think I have ever seen a gas furnace installed with anything other than hardwired armored cable for the 120-volt supply. No one, even in the worst of homes. An appliance cord set to a receptacle might be kosher(?), but I'm pretty sure I have never come across that. Kurt's exposed NM must be a Harry Homeowner install.

[Douglas Hansen]

It's funny how different things are from one part of the country to another. I did a seminar this last weekend in Reno and the inspectors there told me that they see nothing but cord-and-plug connections, despite the fact that the code prohibits it, and that UL has never listed a forced-air furnace with a cord-and-plug connection. Around here we see a few jack-leg installations with NM cable. Kurt's is relatively clean. Aside from the potential damage issue that Marc mentioned, usually the problem with NM is that it is not secured properly and that it is strung through the air, rather than following the building surfaces and framing.

Kurt, it isn't NMC - it is just NM. NMC is a special type of cable used in barns and rated for corrosive environments. Look on pages 246-252 for more than you ever wanted to know about NM, and on page 251 for the skinny on NMC.

[Chad Fabry]

That installation is so ubiquitous in our area it's become one of the things that makes every report like neutrals and grounds under the same screw and NMS issues under sinks. I don't think I've ever seen a furnace with compliant wiring.

[Greg Booth]

That installation is so ubiquitous in our area it's become one of the things that makes every report like neutrals and grounds under the same screw and NMC issues under sinks. I don't think I've ever seen a furnace with compliant wiring.

..........what Chad said. I can't remember when I've seen a furnace wired with anything other than NM.........Greg

[Jim Port]

Unless someone deemed that cable subject to physical damage it would be compliant if the strap was listed for the use.

Like Doug said, I too have never seen a furnace listed for use with flex cord.

[Douglas Hansen]

Since exposure to physical damage is not clearly defined, it seems that in some parts of the world inspectors are touchier about it than in other parts. Jim, in Maryland don't you folks routinely see it on basement walls? Looking at this photo of some fans in a basement, would it draw a correction notice in your part of the world? Around here, it would be written up as a violation of 334.15(A) & (B).

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[kurt]

Kurt, it isn't NMC - it is just NM. NMC is a special type of cable used in barns and rated for corrosive environments. Look on pages 246-252 for more than you ever wanted to know about NM, and on page 251 for the skinny on NMC.

Double thanx.

I'm learning whole big bunches of new stuff with the new book. It's really wonderful.

[Jim Port]

Doug,

It was typical to see the NM on furring strips, although sometimes I did see it run just on the block.

Couple of issues in the pics, one not secured within 12" of the boxes and IMO it does not follow the building surface closely enough due to the lack of being unsecured.

[rkenney]

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From an electrician's perspective diagonal wiring always draws attention. No clamp where it exits the wall.

[Jim Port]

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From an electrician's perspective diagonal wiring always draws attention. No clamp where it exits the wall.

Why do you think the cable needs a clamp where it exits the wall? What type of clamp is listed for that use?