Power Via Cat5e To Pan/Tilt/Zoom Cameras?

[Investigate.Laws]

Many manufacturers today offer interface baluns for classroom pan/tilt/zoom video cameras. Some of these interface baluns feature HDMI, RS-232 control and camera power ports. So one would plug a typical PTZ camera's RS-232, HDMI and power into the ports on one side of the balun #1, which would be secured near the location of the camera itself. Then, presumably, one would plug one end of a long, plenum-rated CAT5e cable into the CAT5e port on the that same balun and the single CAT5e cable would simultaneously convey 1) video, 2) control via RS-232 and 3) power to the balun #2 located in a control room located on the other side of the classroom. This single CAT5e cable would presumably run through conduit in the wall from the camera and then up over the drop ceiling tiles (via appropriate conveyance) and then down a conduit inside of the control room wall and then into the control room to the balun #2. (Balun #2 would be plugged into a typical wall outlet, which would be the source of the power to the camera.) It would be a point-to-point connection. An example of this type of balun is the Vaddio OneLINK for Cisco PrecisionHD 1080p 12x Cameras.

The idea sounds great. Cables are minimized.

But it's not clear in my mind how a flexible, CAT5e cable for power is any different (as far as code requirements are concerned) than a flexible extension power cord, which presumably would be illegal if it were running above a commercial ceiling grid.

Am I explaining my confusion with sufficient clarity? If so, can one of you kind souls please enlighten me?

 

[iwire]

But it's not clear in my mind how a flexible, CAT5e cable for power is any different (as far as code requirements are concerned) than a flexible extension power cord, which presumably would be illegal if it were running above a commercial ceiling grid.

Article 400 contains the section that prohibits cords above ceilings, but article 400 only applies to the types of cords specifically listed in article 400.

Your example of cat 5e would be covered under article 725 and / or another article in chapter 800 and not article 400.

 

[Investigate.Laws]

OK, thank you.

One more question: Some microphone manufacturers offer ceiling-mounted microphones that are powered via so-called "phantom" power. These types of microphones feature XLR style audio cables that are intended to be inserted through the ceiling and then conveyed over the ceiling tiles and into a control room where a rack-mounted mixer or video codec would be plugged into a typical wall outlet (source of power).

Would this type of flexible cable fall under the same section that you just cited?

 

[hbiss]

I think you are not seeing the forest for the trees. Any cable installed within a structure, whether it carries power or not, must be listed for the purpose and location. If you use the equipment manufacturer's designated wiring method and recommendations (in your two cases audio cable with XLR connectors and CAT5 cable) you can be certain that the wiring method is suitable for supplying any power that the equipment needs.

Your only concern then is choosing a suitable cable (audio or CAT5) for the environment. If for instance you will be installing the cable in a ceiling air handling space you would choose a plenum listed CAT5 or audio cable (CMP). Likewise, vertical runs between floors would require a riser or better listed cable (CMR or CMP). Otherwise for just running within walls you can use regular CM.

So to answer one of your original questions, if you can find lamp cord that is listed CMP, CMR or CM go for it.

-Hal

 

[Investigate.Laws]

Thank you. This has been very helpful.

I especially appreciate the reference to NEC Article 725 and its information about "limited-power circuits" and "class 2" power sources. That's key information.

Thanks again.

 

[Investigate.Laws]

One more question. If the above-drop-ceiling airspace of a hypothetical classroom had an air handling configuration such as this ("there is no plenum airspace") -- would that still be considered a "plenum" airspace in the eyes of some local jurisdictions?

 

[Investigate.Laws]

Or would this space above the ceiling tiles be considered what Article 300.22(c) describes as "Other Spaces Used for Environmental Air (Plenums)?" If this type of airspace is considered "Other Spaces Used for Environmental Air (Plenums)," then would plenum-rated cable be required in lieu of metal conduit?

My guess is: Yes, plenum-rated cable would be required in the absence of metal conduit.

But certain local associates dispute this when I discuss this question with them. (They seem to think no metal conduit is required and no plenum-rated cable is required.)

 

[GoldDigger]

It does not help that the NEC specifically requires plenum rated methods in "environmental air spaces" that it just as specifically defines not to be actual plenums.

Tapatalk!

 

[Investigate.Laws]

That's the heart of my question.

Many of my associates say we have classrooms with drop-ceilings and that the space above those drop-ceilings is not true plenum space and they point to the blue drawing at this Wikipedia Web page to show how our air returns are routed VIA DUCTs. In other words, the return air is not drawn up into a ductless space above the ceiling tiles. The return air is drawn into sealed ducts. So my associates say this is not a true "plenum" because the airspace above the ceiling tiles is "dead" and they reason that, because of this, no plenum-rated cables are required in the space above the ceiling tiles. And they reason that no metal conduit is required above the ceiling tiles (for audiovisual cables).

I'd like to find out if this is, indeed, true.

I do know that InfoComm (the professional association representing the audiovisual industry worldwide) states that it is "best practice" to run audiovisual cables through metal conduit EVEN IN LOCAL JURISDICTIONS WHERE NO CONDUIT IS REQUIRED.

But, of course, that's just a "best practice" defined by an industry association. It's not the NEC code.

I'm trying to find out what the NEC code says about above-ceiling-tile spaces such as this where the return air is routed through ducts.

 

[GoldDigger]

I'm trying to find out what the NEC code says about above-ceiling-tile spaces such as this where the return air is routed through ducts.

Mike Holt's presentations on the subject tell us that under the NEC such a space is neither a plenum nor an environmental air handling space. So code sections related to those two conditions would not apply.

However, the space is still above a dropped ceiling and so any code sections based on that alone would still apply in full.

Disclaimer: Mike Holt educational materials are darn good, and well researched, illustrated and discussed, but they are not enforceable any more than the Handbook is.

 

[Investigate.Laws]

Thank you so much.

OK. That does seem to suggest that my colleagues may be correct and that plenum-rated audiovisual cables would not be required and metal conduit would not be required in the space above our ceiling tiles.

However, I wonder -- in my own mind -- whether it's wise, in the long term, to not use either plenum-rated cable or metal conduit in these types of spaces. Because there is breathable air in these types of spaces. I know because I've been up there on a ladder and I've breathed the air many times.

In addition, people sit in seating below these types of spaces.

So... hypothetically speaking... I can see how non-plenum-rated cables might catch fire up there and toxic gas might be produced... even though -- technically -- such a space may not be a plenum nor any other type of space where plenum-rated cables or metal conduit are required.

What is the NEC thinking on this subject? Do they believe there isn't sufficient air up there to sustain a fire of significance? I'm not sure what they might be thinking. It seems inconsistent.

InfoComm training states: "In jurisdictions where the use of conduit is not required, it is still best practice to use it because of the physical and signal protection it affords." (Page 319 of 526, CTS Certified Technology Specialist Exam Guide by Brad Grimes, Second Edition, 2013)

When InfoComm points to "physical protection" provided by metal conduit, I assume that means physical protection for people sitting beneath cable that could become molten, if it were to catch fire and burn.

So that's why the NEC code -- if it doesn't mandate metal conduit or if it doesn't mandate plenum-rated cable in these types of spaces -- seems a bit puzzling (and perhaps inconsistent?) to me.

 

[mgookin]

Thank you so much.

OK. That does seem to suggest that my colleagues may be correct and that plenum-rated audiovisual cables would not be required and metal conduit would not be required in the space above our ceiling tiles.

However, I wonder -- in my own mind -- whether it's wise, in the long term, to not use either plenum-rated cable or metal conduit in these types of spaces. Because there is breathable air in these types of spaces. I know because I've been up there on a ladder and I've breathed the air many times.

In addition, people sit in seating below these types of spaces.

So... hypothetically speaking... I can see how non-plenum-rated cables might catch fire up there and toxic gas might be produced... even though -- technically -- such a space may not be a plenum nor any other type of space where plenum-rated cables or metal conduit are required.

What is the NEC thinking on this subject? Do they believe there isn't sufficient air up there to sustain a fire of significance? I'm not sure what they might be thinking. It seems inconsistent.

InfoComm training states: "In jurisdictions where the use of conduit is not required, it is still best practice to use it because of the physical and signal protection it affords." (Page 319 of 526, CTS Certified Technology Specialist Exam Guide by Brad Grimes, Second Edition, 2013)

When InfoComm points to "physical protection" provided by metal conduit, I assume that means physical protection for people sitting beneath cable that could become molten, if it were to catch fire and burn.

So that's why the NEC code -- if it doesn't mandate metal conduit or if it doesn't mandate plenum-rated cable in these types of spaces -- seems a bit puzzling (and perhaps inconsistent?) to me.

I think you're getting off course there. Let's look at why we use plenum rated cables. A plenum is a return air stream. If there is a fire in that area, we don't want to draw that air containing products of combustion into a return air stream and eventually to a supply air stream. The plenum rated cable will produce less toxic products of combustion. It's not about the cable catching fire and falling on someone.

And you still have to deal with "above ceiling tiles".

You have a choice - code minimum or best practices. You have information to make an informed decision.

 

[Investigate.Laws]

It's not about the cable catching fire and falling on someone.

Then somebody had better correct the information published in this December 1, 2007 article published by "Security Distribution & Marketing" magazine. According to the article (entitled What Technicians Need to Know about Cable & the NEC), "When installers lay cable on top of a drop ceiling, as mine did, it is not permissible by the NEC because the drop ceiling is not part of the true building structure. 'That?s a fire safety issue, because if there?s a fire and that ceiling drops down, you?re going to get hot molten cable dropping down, too. That ceiling will eventually give way and all that heavy copper cable will drop down,' McLane explains."

To give you some background, a project manager for the construction firm that remodeled my building once advised me to secure audiovisual cables to the wire that supported the drop-ceiling.

But I agree it boils down to a choice between "best practice" and "minimum code requirements."

 

[hbiss]

Then somebody had better correct the information published in this December 1, 2007 article published by "Security Distribution & Marketing" magazine. According to the article (entitled What Technicians Need to Know about Cable & the NEC), "When installers lay cable on top of a drop ceiling, as mine did, it is not permissible by the NEC because the drop ceiling is not part of the true building structure. 'That?s a fire safety issue, because if there?s a fire and that ceiling drops down, you?re going to get hot molten cable dropping down, too. That ceiling will eventually give way and all that heavy copper cable will drop down,' McLane explains."

Well, about all I can say is don't believe everything you read. A lot of these authors that write for these magazines think they are experts. They are not and the readership doesn't know any better and will never call them on the wrong information.

The main reason cables are prohibited from laying on the grid is because they hinder access to the ceiling space above. Ever tried to push up a tile with 100 cables lying on top of it? There is a concern about what will happen in the event of a fire but it's hardly what that guy asserts. Firemen will pull the ceiling down looking for hot spots so you don't want a rats nest hanging down in the way. Matter of fact all ceiling mounted items like light fixtures must also be independently supported to the structure to keep them from falling if the ceiling is pulled down.

To give you some background, a project manager for the construction firm that remodeled my building once advised me to secure audiovisual cables to the wire that supported the drop-ceiling.

That's wrong too! You cannot attach to the ceiling support wires. You must install your own.

-Hal

 

[Investigate.Laws]

Well, about all I can say is don't believe everything you read. A lot of these authors that write for these magazines think they are experts.

The molten cable remark is not from the magazine author (Ms. Laura Stepanek). That molten cable remark, if you read closely, was a quotation from Mr. Bryan McLane, vice president at the Las Vegas National Training Center, which develops and conducts training for National Institute for Certification in Engineering Technologies (NICET). That organization focuses on mechanical and electrical systems. The National Training Center writes and publishes professional references which are used as the standard for the fire protection and low voltage industry. Just saying.

 

[Investigate.Laws]

You cannot attach to the ceiling support wires. You must install your own.

The project manager -- the self-proclaimed expert -- advised me to attach the audiovisual cables to the drop-grid ceiling. That's why I mentioned it: to point out there are many people in the building industry who don't understand fire safety. I had already read the article in the magazine cited previously. So I knew that attaching cables to the drop-ceiling support wires didn't make sense. The problem in many of these types of circumstances is the lack of planning and lack of attention to detail by senior administrators. In the circumstance to which I pointed, that meant there was no metal conduit (because nobody in the senior ranks wants to approve the cost). So what happens in these situations is that technicians are left with no resources and are then forced to come up with cable installation options. If it were up to me, I'd opt for metal conduit installed by a licensed electrician for all audiovisual cables. Period.

 

[hbiss]

?That?s a fire safety issue, because if there?s a fire and that ceiling drops down, you?re going to get hot molten cable dropping down, too. That ceiling will eventually give way and all that heavy copper cable will drop down,? McLane explains.

That's a stretch of opinion for sure. I've never heard of that concern. I would think that if a fire got going that good that's the least of the problems. Besides, even if the cable is supported it's going to melt and plenum listed cable (I don't believe) will drip.

-Hal