Problems installing doorbell transformer
#1
01-28-17, 11:03 AM
Problems installing doorbell transformer
Installing a new 16VAC doorbell transformer. House only had a wireless doorbell before. I bought this one: Wired Door Bell Transformer-216597 - The Home Depot
I am mounting it to an existing box that has nothing in it yet, other than the incoming line. The line has a white, black and bare copper (ground) wire. The voltage between
white-black is 0V
black-ground is 120V
white-ground is 0V
The transformer has 3 wires, black, white and green. Instructions say to wire white-white, black-black, green-ground. When I do that and turn on the power, the breaker trips. I disconnected the transformer and tested the continuity on the transformer and the black and white lines are shorted. I went back to Home Depot and tested the continuity of the other transformers on the shelf, and all the whites and blacks were shorted. So I guess this is by design. But I can't wire this to my house because it is shorting my house black and white together and tripping the breaker.
Since there is 120V between the house black and ground, I tried wiring the transformer black-black, green-ground, white hanging loose. The breaker does not trip and the output reads 16V as needed. But the white neutral on the transformer isn't connected to anything, and it is not wired per mfr instructions.
What am I missing?
I am mounting it to an existing box that has nothing in it yet, other than the incoming line. The line has a white, black and bare copper (ground) wire. The voltage between
white-black is 0V
black-ground is 120V
white-ground is 0V
The transformer has 3 wires, black, white and green. Instructions say to wire white-white, black-black, green-ground. When I do that and turn on the power, the breaker trips. I disconnected the transformer and tested the continuity on the transformer and the black and white lines are shorted. I went back to Home Depot and tested the continuity of the other transformers on the shelf, and all the whites and blacks were shorted. So I guess this is by design. But I can't wire this to my house because it is shorting my house black and white together and tripping the breaker.
Since there is 120V between the house black and ground, I tried wiring the transformer black-black, green-ground, white hanging loose. The breaker does not trip and the output reads 16V as needed. But the white neutral on the transformer isn't connected to anything, and it is not wired per mfr instructions.
What am I missing?
#2
01-28-17, 11:15 AM
Is this a box and cable you installed. If so where does the cable come from. The white is obviously not a neutral. Ground can not (safely) be used as a neutral.
I doubt it. You have to check with your multimeter set to the lowest ohm scale. Reading should be between 50-200 ohms. Check the battery(ies) in your multimeter.
Main thing now though is full details on the cable you are trying to use.
and tested the continuity of the other transformers on the shelf, and all the whites and blacks were shorted.
Main thing now though is full details on the cable you are trying to use.
#4
01-28-17, 12:40 PM
Group Moderator
Be very careful.
I see it as the ground is possibly hot.
The transformer has 3 wires, black, white and green. Instructions say to wire white-white, black-black, green-ground. When I do that and turn on the power, the breaker trips.
#5
01-28-17, 12:41 PM
Is this a box and cable you installed. If so where does the cable come from. The white is obviously not a neutral. Ground can not (safely) be used as a neutral.
You have to check with your multimeter set to the lowest ohm scale. Reading should be between 50-200 ohms. Check the battery(ies) in your multimeter.
What should these line measurements be?
white-black is 0V
black-ground is 120V
white-ground is 0V
#6
01-28-17, 12:51 PM
Forum Topic Moderator
Black to white should be 120. Black to ground 120, White to ground 0. I would look for the last working outlet and the next one in line for a loose wire, either in wire nut or a backstabed wire. all backstabed wires should be moved to screws.
#7
01-28-17, 01:00 PM
I will replace all the outlets and report back. I already have the new receptacles (I am working on several upgrades currently). I will only use screw terminals.
#8
01-28-17, 03:21 PM
I will replace all the outlets and report back.
#9
01-28-17, 04:00 PM
I mean, I am replacing all my receptacles anyway (from brown to white), so any loose or broken connections will be found and fixed.
#10
01-28-17, 05:22 PM
so any loose or broken connections will be found and fixed.
I am mounting it to an existing box that has nothing in it yet
#11
01-29-17, 10:18 AM
A bit off topic but where is this box. You are saying it was already there? Could you post a picture of ut and the wires inside.
#12
01-29-17, 10:55 AM
Forum Topic Moderator
The transformer is not made to mount inside a box. They mount on the outside, typically on an exposed box.
You also need to keep the line voltage separate from the low voltage.
You also need to keep the line voltage separate from the low voltage.
#13
01-29-17, 11:28 AM
Now you know why I asked where the box was. As PCBoss wrote that won't work. In addition to the code violation there might be heat build up from the transformer.
Is there a near by receptacle box that the cable in the box comes from?
The chime transformer is often mounted on a box in an unfinished attic or basement. Sometimes to side of the breaker box if the breaker box is located inside. You could also place it in a closet using a recessed box and cover plate with a half inch knockout for the ½" nipple on the transformer.
Is there a near by receptacle box that the cable in the box comes from?
The chime transformer is often mounted on a box in an unfinished attic or basement. Sometimes to side of the breaker box if the breaker box is located inside. You could also place it in a closet using a recessed box and cover plate with a half inch knockout for the ½" nipple on the transformer.
#14
01-30-17, 11:13 AM
I am all set! I found the bad outlet in one of the bedrooms. Looked like it shorted out at some point because wires were burnt and brittle. Cut them back and replaced receptacle. All outlets working. Voltages at chime box measure per standard. Thanks all for the help 
#16
01-30-17, 11:37 AM
Are you talking about the mounting of the xfmr? A lot of people mount them to the outside of a box inside the wall. I ran it for a while on the counter and it hardly gets even warm under load. I am using the metal box with one side off to get the whole thing neater, better support, and be able to get to the xfmr easily if I need to (with the hybrid wall plate). What difference does it make if it's on the outside of the box, against insulation in the wall, or the way I did it? Also, I do not have the lv and hv lines together.
#18
01-30-17, 02:15 PM
I am using the metal box with one side off to get the whole thing neater, better support,
