All, I replaced my doorbell transformer and got 22V (which was odd since it is supposedly a 16V transformer) with no wires connected to the transformer. As soon as I connect the wires to the transfomer that run to the chime the voltage drops to 2V or so. What would that indicate?
Electrical – Doorbell Voltage Drops at Transformer
doorbellelectricaltransformer
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Generally the chime will have a solenoid that gets pulled or pushed when the circuit is completed. The solenoid bangs against the metal and you hear the nice chime. [I thought these were 24V circuits - so be sure you check your door bell system out and verify that first.
Check your voltage on the solenoid - you can check resistance with no power attached (should be some low ohms around 4 ohms probably.) When your door bell button is pushed voltage will flow from the Transformer into your solenoid - so checking the voltage at the solenoid will provide an answer as to what is working and what is not working.
You should be able to measure your 'voltage drop' at the solenoid when the doorbell circuit is made. Use Ohms Law - the voltage you know is 16V, the ohms is the resistance of the solenoid. Your solenoid even though it is an inductor has resistance - so it is your equivalent to a resistor in the example link.
Here is a quick link: http://www.wikihow.com/Calculate-Voltage-Across-a-Resistor
Some things to keep in mind: 1: Solenoid sticking - clean it and use graphite lock type lubricant. 2: Solenoid open or shorted.. 3: Transformer not working or "Overloaded" - too much current draw causes the voltage on the transformer to drop and it will not be able to pull in the solenoid. This indicates either something shorted - or a wrong doorbell chime, or a transformer that is simply worn out. 4: Doorbell switch bad .. or too much resistance - simply put one wire to the other and see if the thing works - if it does the switch is bad.
It's OK (desirable, actually) if the new transformer's VA is higher. The transformer VA rating indicates how much load the transformer can safely support. The doorbell VA rating indicates how large the doorbell load may be. It's important for the voltages to match and for the VA rating of the transformer to be higher than the VA rating of the loads (the sum of the chime and the Ring device). This is analagous to payload capacity of a vehicle: the actual load should not exceed the carrying capacity.
Since tracing the low-voltage doorbell wire back to the transformer isn't working, maybe you can work the other direction. Turn off all circuits in the building except the one that powers the doorbell. If the circuit isn't marked, turn off circuits one at a time until the doorbell doesn't work anymore.
With the supply circuit identified, and with only that circuit powered, you could trace that circuit with a the tone pickup tool you've been using, a non-contact voltage tester, the live wire warning in a stud finder tool, etc. "In theory" by inspecting every connection along that circuit's path you'd eventually find a pair of light-gauge stranded wires spliced into the circuit somewhere. Those would be the leads of the existing bell transformer.
Even if the transformer is mounted somewhere awful, like on the back side of a steel outlet or light junction box behind a finished wall or ceiling, at least its mains power junction should be accessible and therefore disconnectable.
Best Answer
Assuming you have a full mains voltage going into the transformer, then there is a short-circuit in the wiring (or, much less likely, the transformer is vastly underrated for the current drawn).
"Bell wire" has thin insulation, compared to mains wiring. A staple may be pinching the wires, or wires could have rubbed together, tearing the insulation. Sometimes mice or squirrels can cause this. Such a short could have burned out the old transformer.
Another possibility is a short in the chime, which then caused the contacts of the doorbell switch to fuse together.
Also, inspect your connections to the transformer. If there are multiple wires, e.g. from both a front and a back door switch, they could be misconnected.
If you can, check the resistance between the bell wires going to the transformer secondary. The resistance should be greater than 16 divided by the current rating of the transformer, or (16 x 16) divided by the VA rating. For example, if the transformer is rated 10 VA, then circuit resistance should be greater than 256/10, or ~26 ohms. (Not to worry if it's just a bit lower, though: you're measuring DC resistance, while AC reactance across a coil is higher.)
Don't be concerned about the 22 VAC open circuit output because the nominal voltage, 16 VAC, is at the rated load.
BTW, my compliments on checking the voltage on installation! Had you not done so, the transformer would have burned out again, or there is a small possibility of fire if a "short-circuit" is a few ohms and is by something flammable.