Question about using fire alarm cable for 120v power supply;

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herding_cats

herding_cats

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Kansas
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Mechanical Engineer
Thanks everyone in advance:

I have a networking project inside a grocery store. I have multiple routers and other equipment all over the place. My question is:

I need 120v in about 15 different places in the grocery store, but they all need to be UPS power backed up. Is it legal to use fire alarm cable to power my routers and other computer equipment? By fire alarm cable I mean the classic red shielded solid core w/G (#16 or #18) that's in every building. I plan to have the 120v distribution from my battery UPS bank and switch.

The amperage loads on these router stations in mA. It's tiny.

I can't think of any commercial building code that says you can't do this? Or am I wrong?
 
It would basically be a 20A circuit? If I fuse it all to 5A would that be ok?. OCPD is upstream of the UPS batt bank/switch.
 
No, you must use a Chapter 3 wiring method. A bigger question is why do you have network equipment scattered all over the store? This would normally done in a central rack. And if you have some equipment that must be located outside the rack it would be POE powered from the rack.
 
yes i think it is rated to 600v like a lot of romex etc.

i'm running 120v just like the fire alarm guys do.
 
The routers cannot be PoE. We have a few devices that are PoE. Our network has a bunch of PLCs, CTs, temp sensors, etc. There are about 15-20 areas like this that need 120v backed up with UPS.
 
Not a subject I know much about, but Chapter 9 Table 11(A) on AC Power says that a 100 VA source at 120V can be Class 3 if it has overcurrent protection. So are there commercially available Class 3 120VAC power sources with overcurrent protection that would fit the bill for the OP?

Cheers, Wayne
 
Trying to avoid MC cable was the idea. FIre alarm cable cost much less and easier to pull. But yes thats the idea.

also I have never seen 16-2 MC cable.
 
If you were truly supplying art 725 items you may be able to do this. But sounds to me like you are supplying power to items that also have additional art 725 or even art 800 components that connect to them via separate wiring methods. Therefore these power circuits are covered by chapters 1-4.
 
herding_cats said:
The routers cannot be PoE. We have a few devices that are PoE. Our network has a bunch of PLCs, CTs, temp sensors, etc. There are about 15-20 areas like this that need 120v backed up with UPS.
Click to expand...
How big are the routers exactly? I have used some really useful PoE to 12 V adapters for numerous projects like this in the past. Getting everything possibly on a couple PoE+ switches really simplifies the management.

E.g. adapter: https://www.amazon.com/REVODATA-12V-2A-Surveillance-PlugPS5712TG/dp/B08HS4NT13
 
The power source for CL2 and CL3 must be listed. You can't just add an overcurrent device to a non listed power source.

If you want to distribute 120 volt branch circuits you need to use a chapter 3 wiring method. What you are suggesting is no different than a homeowner/handyman using zip cord for branch circuit wiring.

Why so many switches? Extend the network cables back to central switch or a couple central switches.

Do the switches supply PoE devices? Do the switches have an internal power supply or connect to a wall-wart/brick?
 
curt swartz said:
The power source for CL2 and CL3 must be listed. You can't just add an overcurrent device to a non listed power source.
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But are there commercially available listed CL3 120VAC power supplies (100VA maximum per channel) that you can use to power arbitrary 120VAC low power loads? Or must the load itself be classified as CL3? Is the typical wall wart CL3 when considered as a load (not as a power source)?

Seems to me if the equipment all has wall warts to convert the 120VAC down to DC, it might be better/easier to distribute DC. E.g. via POE or the like. Even if that requires bodging together a few different solutions to get the various voltages for different devices.

Cheers, Wayne
 
What is the marking on the fire alarm cable? Check the cable substitution tables in 725 and 760...or if you are using the 2023 in new Article 722.
 
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