After testing the primary electrical cable with a volt meter I was able to determined that the output was around 120 volts. I then shut off the breaker and connected a low voltage transformer to be used for one door chime. Before connecting the secondary electrical, I turned on the power and notice a prominent buzzing sound emanating from the transformer. Less than a minute later a little bit of smoke came out of it. Needless to say, the transformer was really hot when I touched it. Fortunately I had 3 of the same transformers on hand and I tried another with the same result. I made sure the black and white wire coincide with each other on both ends, the primary cable and the transformer. The transformer specs are the following; input 120-volt AC, output 16-volt AC / 10-volt ampere MODEL Heath Zenith 122C-A. What am I doing wrong?

Transformer wire colors?

What colors were connected to 120 VAC?

What was the measured voltage?

A "trick" in this case is to use a 7W light bub (night light) in series with the 120 V input to the transformer. With no load, it should not glow. If you picked the wrong wires, it would glow and would not cause damage.

Since your capable of measuring the primary of 120 V, you should measure the secondary and get 16 V.

But first, what are the colors? And second
What side to they come from? e.g. black/white = side A, blue/blk side B

To KeepItSimpleStupid.

Thank you for the quick reply. I measured the secondary source and I'm getting around 24 volts on one of the wires and the other one is around 8 volts. I took a picture for your reference. Your help is appreciated.

http://j.imagehost.org/0562/wiring.jpg

Quote:

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Originally Posted by KeepItSimpleStupid

Transformer wire colors?

What colors were connected to 120 VAC?

What was the measured voltage?

A "trick" in this case is to use a 7W light bub (night light) in series with the 120 V input to the transformer. With no load, it should not glow. If you picked the wrong wires, it would glow and would not cause damage.

Since your capable of measuring the primary of 120 V, you should measure the secondary and get 16 V.

But first, what are the colors? and second
What side to they come from? e.g. black/white = side A, blue/blk side B

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Please take a look at your picture.

Questions:

Where is the 120 VAC coming from? Is it supplied at the door bell switch or is power supplied to the input of the transformer and then off to the switch?

A cursory look at the pic and it appears to be wired incorrectly.

Do you see the white conductor with the black tape on it. This means that that conductor is a "Hot" wire, it is not Neutral.

Normally, in a properly connected switch loop, this wire would be connected to the black feed and will carry power away from the source to one side of the switch. The return from the switch would normally be the black and it would connect to the primary feed on the transformer. The White on the transformer would connect to the white on the feed Neutral (White).

So I'm really not sure how this is wired. Is there a switch siting on the primary side of the transformer?

What do you have connected to the low voltage wire on the secondary conductors?

Yep, totally confused.

First, the primary. Basically what Donf said. Usually black taped white wires are part of a switch loop. In other words we would expect the blue cable to go to the two terminals of a switch and power would be supplied by another cable.

There is no Romex connector (Strain relief) on the blue cable.

So, what do you have on the what and blk wires going to the transformer. Are there any switches in ivolved.

The secondary:
Usually they have isolated outputs or they are multi-tapped.
One could be C 16 24, say for a 24 V transformer with 3 terminals.

Need a pic of the terminal side of the transformer.

Meanwhile connect a 120V lamp to the black and white wires of the green cable ans see what happens. No transformer.

Besides the other problems with what voltage the feed is, and is it a 120 volt feed, the blue cable needs a connector where it passes through into the 4 inch round box.

Before dealing the with output of the transformer, need to confirm that only 120 volts is feeding the transformer.

Sure is odd that white has been marked, as if a switch loop or a 240 volt feed.

Agreed, the black tape may be the other leg(240 volts) and be too high for the transformer.
Verify Voltage with a tester.
Need Connector for the blue cable.
Measure voltage on transformer, hook up secondary wires, and recheck voltage, low you have a short or a high load.
You should have more than 16 volts AC with no load.
I don't understand 8 and 24 volts, you have 2 terminals?
If measuring off ground, 1 of the secondary wires may be touching transformers metal case, Side Picture?