door bell transformer location

Status
Not open for further replies.
G

Greg1707

Senior Member
Location
Alexandria, VA
Occupation
Business owner Electrical contractor
Is it permissible to install a doorbell transformer within a non metallic 2 gang box? I have a customer with no doorbell that wants to ad the NEST Video doorbell. It would be convenient to install the transformer in a box near the front entrance door.
 
Greg1707 said:
Is it permissible to install a doorbell transformer within a non metallic 2 gang box? I have a customer with no doorbell that wants to ad the NEST Video doorbell. It would be convenient to install the transformer in a box near the front entrance door.
Click to expand...
Why not go for a wireless one? Problem solved at a stroke.........
 
Greg1707 said:
Is it permissible to install a doorbell transformer within a non metallic 2 gang box? I have a customer with no doorbell that wants to ad the NEST Video doorbell. It would be convenient to install the transformer in a box near the front entrance door.
Click to expand...

I had a customer ask me to do the same thing. I didn't end up doing the job, but I would have done it the same way you are proposing. The case of the transformer needs to be grounded. As long as the ground is installed I see no reason why a plastic box would be a violation. I don't think those transformers get hot so ventilation should not be an issue, but if it is, the blank cover can have a couple of slots installed.
 
Second reason but I think exception one means more than one metallic cable. I infer one would be ok but you are actually installing the trany in the box. IMO, violation

314.3 Nonmetallic Boxes. Nonmetallic boxes shall be permitted
only with open wiring on insulators, concealed knoband-
tube wiring, cabled wiring methods with entirely nonmetallic
sheaths, flexible cords, and nonmetallic raceways.


Exception No. 1: Where internal bonding means are provided
between all entries, nonmetallic boxes shall be permitted
to be used with metal raceways or metal-armored cables.


Exception No. 2: Where integral bonding means with a
provision for attaching an equipment bonding jumper inside
the box are provided between all threaded entries in
nonmetallic boxes listed for the purpose, nonmetallic boxes
shall be permitted to be used with metal raceways or metalarmored
cables.
Click to expand...
 
When I think 'doorbell transformer' I think of a small transformer that has a nipple coming out of it which goes into a metallic box to the 120V wiring. I don't think you could install one of these on (or in) a plastic box in a compliant fashion.

But there are alternatives that would work. The most common seems to be a 'wall wart' power supply plugged into a receptacle installed in a box. But I came across this nifty beastie that might work for you:

http://www.nutone.com/products/product/b0c1ef13-7109-4d18-bc10-74a04626a16a

-Jon
 
Dennis Alwon said:
You cannot install a trany in the 2 gang box where the line and load are mixed together, IMO....
Click to expand...

There are many installations of small control cabinets (including plastic ones) containing transformers. I don't see how this would be different.
 
Last edited:
winnie said:
But there are alternatives that would work. The most common seems to be a 'wall wart' power supply plugged into a receptacle installed in a box. But I came across this nifty beastie that might work for you:

http://www.nutone.com/products/product/b0c1ef13-7109-4d18-bc10-74a04626a16a

-Jon
Click to expand...

This device would be fine in a garage, but not in a front entry. It has wires sticking out the front.

A wall wart would not work either. The wires would be visible and would eventually have to go through the wall to reach the doorbell device.
 
Coppersmith said:
There are many installations of small control cabinets containing transformers. I don't see how this would be different.
Click to expand...


It depends on a few factors one being what class the trany is and what insulation is used on the low voltage

I still don't understand what you are doing. Are you installing the trany in the box or outside the box? What do you mean by slots in the cover?
 
door bell transformer location

Dennis Alwon said:
It depends on a few factors one being what class the trany is and what insulation is used on the low voltage

I still don't understand what you are doing. Are you installing the trany in the box or outside the box? What do you mean by slots in the cover?
Click to expand...

I would think OP is going to install an old work box inside next to the door and fish the bell wire up.

“Slots” would be a louvered wall plate. Before Legrand started making their LED devices with a louvered cover that uses a standard decora wallplate, I used louvered plates for night lighting in hallways with small incandescent lamps in the box. Leviton & Legrand both make a yoke with a recessed lamp holder that fits inside a standard wall box; or at least they used to. I’ve put the horizontal ones in baseboards also.


Sent from my iPhone using Tapatalk
 
winnie said:
But I came across this nifty beastie that might work for you:

http://www.nutone.com/products/product/b0c1ef13-7109-4d18-bc10-74a04626a16a
Click to expand...
Only issue is that the LV wires come out of the face. The blank plate may be deep enough to tuck the LV wires and wire nuts into the drywall cut-out, maybe before inserting the old work box.

If there is no receptacle near the door, and/or the doorbell wires have to be fished up (attic space) or down (crawl space), you might as well mount the transformer in one of those spaces.
 
I see this all the time. The doorbell transformer is shoved into a 2 gang box installed high up in the first floor hallway, with the chime doing double duty as a face plate. Im not saying it's the right way to do it, but it seems to be getting passed in new construction around atlanta. It might just be one of those things the inspectors are so used to seeing they don't even think about it.

For what its worth, i don't often come across one's with signs of heat damage to the wiring in that box, unless its got a lighted push button. In the case of the nest that transformer will be providing a continuous load (just like for the lighted push buttons)...its not going to have a chance to cool down.

Another nest note. A lot of the AHJs around me, there's tons in the atlanta area, are letting us use the nest smoke/ carbon detectors in leu of hardwired, interconnected smokes. The direct wire nests only have a hot and neutral in the harness, and they will talk with the "10 year" battery ones. Its saved me alot if trouble on service upgrade/ replacements

Sent from my SM-G950U using Tapatalk
 
Last edited by a moderator:
Dennis Alwon said:
I still don't understand what you are doing. Are you installing the trany in the box or outside the box? What do you mean by slots in the cover?
Click to expand...

I can't speak for the OP's situation, but I'll tell you about mine.

Two story house with no existing doorbell wiring. Currently they have a wireless video doorbell that they want to replace with a wired one because they don't like having to remove the wireless and put it on a charger.

There is an inside receptacle near the front door. My plan was to install a plastic two-gang cut-in box near the receptacle. The doorbell transformer would be installed inside this box and powered from the receptacle with NM run between the boxes. The box would have a blank cover possibly with slots/louvers to allow heat to escape. The low voltage cable would be fished to the doorbell location a few feet away to power the device. If an actual doorbell was desired/required in the circuit, it can be placed anywhere along the low voltage wire route.
 
Status
Not open for further replies.
Top