Aircraft Hanger & Low Voltage

[starbright28]

I have a question for you all. This is a direct from the field question. This question is also important that I recieve replies right away as he is looking for the answers.

My dad wired up a new airport hanger. There is overhead garage door motors (to open the door) that is mounted approximately 18 feet from the floor.

He went by all rules in how to wire the aircraft hanger per NEC Code. Low voltage wiring is what came in to question from the Electrical Inspector.

He ran the low voltage wire seperate from the power wire, but he did not put the low voltage wire in any conduit. You can say it is pretty much strapped to the conduit going to the garage door opener motor to the door openers pushbutton.

First Question: Does the low voltage have to be in conduit? Where does it state that in the NEC?

Second Question: 513.7 specifies all fixed wiring in a hanger but not installed in a Class 1 location shall be installed in metal raceways or shall be Type MI, TC or MC cable. What is TC cable?

Third Question: (one he want's clarified, like the question above): Article 501.10 (B) 3 nonincendive Field Wiring. Nonincendive field wiring shall be permitted using any of the wiring methods permitted for unclassified locations. Nonincendive field wiring systems shall be installed in accordance with the control drawing(s). Simple apparatus, not shown on the control drawing, shall be permitted in a nonincendive field wiring circuit, provided the simple apparatus does not intercoonect the nonincendive field wiring circuit to any other circuits.

He wants to know what the heck is nonincendive Field wiring.

Now I decided (because this just popped into my head when I was writing this) to look at the Class 1,2,& 3 remote control, signaling, and power limited circuits. I'm looking at article 725.11(B). Does this apply to my dad's situation, or am I not looking in the right section?

725.11(B) states: where damage to remote-control circuits of safety control equipment would introduct a hazard, as covered in 725.11(A), all conductors of such remote-control circuits shall be installed in rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, electrical metallic tubing, Type MI cable, Type MC cable, or be otherwise suitably protected from physical damage.

Let me know if I'm onto something with that code article.

the final question: Basically does he need to put his low voltage wire in a protective raceway, or can he let his current installation be (no proctection.)

He's not fully "wrote up" on this yet, but if he can do the reaserach on it and ask the head inspector over the local inspector, and he approves the means and method of installation, then he doesn't have to change it.

Thanks for the help!

 

[RayS]

First Question: Does the low voltage have to be in conduit? Where does it state that in the NEC?

Second Question: 513.7 specifies all fixed wiring in a hanger but not installed in a Class 1 location shall be installed in metal raceways or shall be Type MI, TC or MC cable. What is TC cable?

Third Question: (one he want's clarified, like the question above): Article 501.10 (B) 3 nonincendive Field Wiring
He wants to know what the heck is nonincendive Field wiring.

the final question: Basically does he need to put his low voltage wire in a protective raceway, or can he let his current installation be (no proctection.)

He's not fully "wrote up" on this yet, but if he can do the reaserach on it and ask the head inspector over the local inspector, and he approves the means and method of installation, then he doesn't have to change it.
Thanks for the help!

1. not generally, not sure about this location
2. TC=tray cable, installed in cable tray instead or pipe.
3. circuit of a low enough energy that a spark will not ignite the atmosphere in question

one question I ask myself in disputes, is "what is the quickest way to my money" if this is just for one door, I'd pipe it & get paid. I'm all for clarity and understanding, and appreciate the question for learnings sake

 

[thinfool]

The last hanger that I wired was similar....all I did was sleeve the 18/5 thermostat cable (for lv controls) in a full joint of 1/2 emt (properly bushed at the open end). That protected the cable to "above" any height where exposure to damage was likely.

I think that would have been under the 99 code rules.

The only inspector issue that I had was that he decided that a hanger was a 'garage' and required that I install gfci receptacles. I did so under the 'how fast can I get my money' view.

 

[starbright28]

I'll pass this info on. If there is anything else that can be of help for this situation, I'll be sure to pass it along in the next few days!

My dad is still awaiting to know for sure though about the low voltage in conduit. Is the inspector right?

 

[starbright28]

According to what I am hearing/reading: it sounds like everythign must be installed in some sort of protection regardless, and the wire just cannot be stapped along the conduit, correct?

Has many of you dealt with aircraft hangers and this sort of thing?