Doorbell repair? Transformer not grounded?

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Anyone ever replace their doorbell?

Turns out mine has been dead for.. I guess a year now, but it's not like I would know since I never ring my own door bell.
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(I wonder how many people I missed because of this?)


The mains wiring to the transformer had 120V, but the transformer itself produced no voltage (should be around 16V).

I pulled the chime and the transformer off the wall, and one of the "plungers" that makes the noise was flat out MELTED. We had some bad storms about a year ago where the power cut on/off about a dozen times in a 5 minute period, so this probably did it.

Anyway it's weird -- the transformer has 3 wires (black, white, green) but the green wire was snipped off so that it couldn't be connected to the ground wire. (the junction box this was in has a bare copper ground) The builder of the home must have done this. But why? Wouldn't grounding the transformer have kept it from dying during a power surge?

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Originally Posted By: Reddy45
Wouldn't grounding the transformer have kept it from dying during a power surge?

I dont think so. I think grounding pertains to the metal part of the doorbell itself being "live" in case the live wires some how come in contact with the doorbell. If you can't fix it you may want to consider buying a wire-less doorbell.
 
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How old of a home?

Our transformer is ungrounded because it's plugged into a two-prong outlet in the basement. Has been this way for probably 50-100 years.

That ground is just a chassis safety in case a winding gets shorted to the case. It has no role in anything else. Asssuming its new construction, I'd have assumed the builder would wire it stratight to Romex, and it would be a no brainer to ground.
 
Originally Posted By: JHZR2
How old of a home?

Our transformer is ungrounded because it's plugged into a two-prong outlet in the basement. Has been this way for probably 50-100 years.

That ground is just a chassis safety in case a winding gets shorted to the case. It has no role in anything else. Asssuming its new construction, I'd have assumed the builder would wire it stratight to Romex, and it would be a no brainer to ground.


14 years old, so newerish construction.

The black and white wires were wired direct to romex with wire caps.

Anyway I found a replacement for around $20 shipped so no biggie.
 
Bad installers snip off wires so they don't have to connect them!!
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A ground wire on a device, does nothing for lightning, but provides a path to
ground to blow / "clear" the fuse so the faulty device no longer has power on it.

These transformers usually make 24V AC, but measure lower depending on the meter you use (AC true RMS,
AC average responding or just crummy!)

In your case, it's likely the chine faulted and melted and took out the transformer, they often
have a small thermal link inside the transformer winding.

If you're next transformer has a green wire, ground it, they provided a wire since the metal
core of the transformer is not connected to the outside housing, a 2 wire transformer will
have the core bonded to the housing per UL and CSA certification rules.
 
Originally Posted By: Reddy45

I pulled the chime and the transformer off the wall, and one of the "plungers" that makes the noise was flat out MELTED. We had some bad storms about a year ago where the power cut on/off about a dozen times in a 5 minute period, so this probably did it.


I had a melted plunger/striker when the house was about 5 years old. I got a kit with a mechanical bell from Home Depot for about $15. I just installed the bell, left the rest in the box.
 
The chime solenoid and the transformer are only designed for intermittent duty. If the solenoid melts and/or the transformer burns out, either the button is stuck or someone has been holding it down for several minutes at a time.
 
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