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Arthur,
Here in N.J. on new jobs low voltage permits have to be pulled. You either have to have an electrical license or low voltage exemption issued by the state. A job I did two years ago the inspector checked to make sure the cable was plenum and that I had grommets in the aluminum top plate. I was told I hade to move my wall phones down from 52 inches to 42 inches.

Must have been a short person area.

Some local areas around western PA require low voltage inspection. Every job I have been on that required the inspection was a joke. The town or borough was ONLY interested in the money. The people that show up (if they even do show up) are clueless. On one particular job, the female inspector was looking at the main electrical panel and inquired if the phone and data wiring were located in the main panel. I said "No. That would be a violation of the NEC." "What is NEC?" She asked. The towns and boroughs view this as a new source of revenue and they don't have to do anything to get it.

Rcaman

As a LV contractor you are supposes to KNOW how to tell or where to find out when the space above a hung ceiling is used as an air handling space. Depending on the size of the job this can save you a lot of money if you don't have to use a plenum listed cable.


In NY it all depends on the jurisdiction since we have neither statewide licensing or, in many cases inspectors that work for the jurisdiction. Here in this town you don't need a license but you do need to have your LV inspected (rough and finish) by an electrical inspector. We have a choice of inspection companies that we can go to to provide an inspection and if you ask them to come out and look at LV work they are going to look at it.

One common way hacks get around this is to come in after the final inspection when everything is closed up.

In this business, it's the honor system. Yes it can be. Even when your work is inspected, after awhile inspectors get to know you and your work and don't scrutinize because they trust you. That's not to say that as a professional you should take advantage of it. Whatever work you do, whether or not it's going to be inspected, should be done in compliance with the Code and customary workmanship standards. So if you have a ceiling that requires plenum listed materials it's on you to do it that way. It's what separates us from the hacks.

-Hal

Yes, you are correct and as an LV contractor, this is a constant discussion I seem to have with people who should know better and think all space above a drop ceiling is plenum yet they don't think space below a false floor can be a plenum.

The trick is whether the inspector knows the difference or not. Most commercial buildings here require the electricion to use BX so to avoid conflict I use only plenum. As they say you might be right but you can't fight city hall.

"BX", as in type AC cable, is a thing of the past. The new industry standard is type MC cable since the 80s. True, people still use the misnomer "BX". National codes require metallic wiring systems in structures over three stories, with some residential applications being exempt from this requirement.

By the way, I hear that Southwire and several other manufacturers are bringing back "BX" cable, but it now includes a #10 aluminum bonding conductor instead of the original flimsy aluminum strip.

As others have mentioned, never, ever, assume that an installation requires plenum rated cable. This can make or break a deal by thousands of dollars in material cost. Plenum cable isn't better, and non-plenum cable isn't inferior. It's all about what is required for the application.

NM (Romex) is prohibited above ceilings (except in some residential) even if they are not air handling spaces. Interesting what you said Ed about the "new" AC, probably going to cost about the same as MC but there is a slight labor savings by not having grounds to terminate. As far as I'm concerned everything should be MC, you treat your green grounds just like Romex grounds. If we did away with Romex it would put yet another nail in the fake science of arc-fault breakers, the biggest fraud on homeowners of all time.

-Hal

Ed,
You are right I just say BX because that's what it was called when I started out. You are also right electrically there is no difference between pvc and plenum. The difference is the burn rate and toxic fume output, so I'm told. Yet alarm companies mount panels with lead acid batteries above drop ceilings?

So I spoke with the electrical inspector. He said he was fine with this approach and it didn't matter if patch panels and a backboard were above or below ceiling height as long as there are no devices above the ceiling.