Hi folks, anyone have an answer to this one.

What are the implications of miswiring a doorbell?

Specifically, our original chime unit did not identify the transformer contact so when I went to replace it, I had no idea which of the two wires heading to the chime unit was from the transformer. It seems to be working but every how-to I have read suggests it is very important not to reverse the wiring.

Would the system even work if the button wire went to the transformer contact and the transformer wire to the button contact? Would it be at all dangerous?

Thanks for any help you can provide.

--Matt

 

Read the voltage on the transformer side going to the chimes. If I am not mistaken the secondary of the transformer should normally be 24 volts ac.

 

Thanks for the tip. I will check the voltage today...what should the voltage of the button wire be vs. the transformer line?

Also, in the meantime, what's the worst that could happen if it is miswired?

Thanks,

--Matt

 

The "worst" that could happen would be if you connected the wires from door-button directly across the 2 wires from the transformer. Pushing the button would short-circuit the transformer but the buttonwould have to held pushed for a prolonged period to damage the transformer.

 

Power runs from one screw of the transformer to one screw of the doorbell button, then from the other screw of the doorbell button to the front or rear (depending upon button location) screw on the chime. The common screw on the chime completes the circuit back to the transformer. In other words, the chime is connected directly to one side of the transformer and the other side of the transformer runs through the buttons. If you describe the wires at each of the 3 locations (buttons, chime, transformer) we can tell you what you need to do.

The only damage you can do to the circuit is by making a direct connection between the two screws on the transformer (short circuit). If the connection is not momentary (only when button is pushed), the transformer would burn out fairly quickly.

 

Thanks folks.

Here's a more complete explanation of where I'm at with this and what my essential question is.

1. A wire currently runs from the transformer to the button.

2. A wire currently runs from the transformer to the bell unit.

3. A wire currently runs from the button to the bell unit.

So, I have two completely identical looking wires coming out of my wall that need to be hooked up to the bell unit.

The bell unit has two terminals...one for the button wire and one marked "trans" for the transformer wire.

I took a guess and attached one wire to the trans terminal and the other to the bell terminal on the unit and the system seems to work.

However, I am wondering if I could have made a mistake -- attaching the wire from the transformer to the bell terminal and the button wire to the transformer terminal.

My question is...what would the implications of this mistake be? Would the bell even work if the wires were attached to the wrong terminals at the bell unit? Would it be unsafe?

I understand that I could check the voltage of each wire heading to the bell unit but am unsure of what the voltages should be -- I believe the transformer is 16 volts.

Thanks for everyone's help on this one. I hope this is enough info.

--Matt

 

I'm suspicious of your wiring explanation. When you say "wire" are you referring to a single conductor or a cable? If you only have two CONDUCTORS at your chime, then I don't think you would hurt anything by switching the two conductors. If you had a second button (back door) which would require three wires then you then if you didn't have it wired exactly correctly one of your buttons wouldn't work but it wouldn't damage anything.

How many CABLES are there at each location. A button rarely if ever has more than one 2 or 3-wire cable at it's location. There is normally some sort of splice made at the transformer or chime location. I personally run a 2-conductor from each button to the transformer and a 3-conductor from the chime to the transformer. That way all my splicing is done at the transformer and there are only screw terminals to hook up at the other locations.

If your transformer is not buzzing or isn't hot to the touch then you probably don't have anything to worry about. Your chime would be making some sort of noise if there was a problem there as well.

Where is your transformer located. If it is under the house or in the attic, then you can probably follow the wiring and tell which wire is which. If you then tell us how they are hooked up at the transformer we can probably tell you if your connection is correct.

 

Thanks for the help mcjunk.

I'll try to be more explict with my explanation. Here's a diagram from the doityourself web site showing exactly my situation:

http://doityourself.com/images/tru/doorbell6.jpg

However, on my bell unit, there is one screw terminal dedicated to the "wire" coming from the transformer.

Unfortunately, I do not know which of the two "wires" coming out of my wall is from the transformer and, therefore, was forced to guess which wire goes to which terminal. Essentially, I had a 50/50 chance of getting it right the first time.

I hope this diagram sufficiently explains my situation. The transformer is not hot and while it is mounted in the garage on the other side of the wall with the bell unit, it would be difficult for me to follow the "wires" through the wall to determine which is which. The bell sounds when the button is pressed. So it appears I gambled correctly but I am just trying to figure out if there are consequences to miswiring at the bell unit. I suppose I could reverse the wires at the bell unit and see what happens but I'd like to avoid that if I can.

Thanks again.

 

Do you have a VOM (volt ohm meter)? They don't cost that much and come in very handy in situations like yours. Set the meter to the ohm scale and tie two wires together at one end of the circuit (at the doorbell button). Touch the VOM probes to the wires at the other end (at the transformer) The VOM needle will deflect upscale when the probes touch the two wires that are tied together at the doorbell button.

http://www.eatel.net/~amptech/elecdisc/vomillia.htm



God Bless the USA! Pray for and support our troops and POWS!

 

According to your diagram, you cannot mess up the wiring. Reverse the two wires at the switch and they still complete the circuit. Reverse the two wires at the bell and they still complete the circuit. The only way you can mess up is to connect the high-voltage side of the transformer to the bell/switch circuit, and you'd know in an instant if you did that.

Now, if it was a 24vDC circuit instead of a 24vAC circuit you'd have some problems with polarity. But that's another discussion.

My question is, what happens in that wiring scheme if you ever wanted to add a second switch at the back door?

 

In answer to rick's question, there is another terminal for the backdoor on the bell unit. But we don't have a back door that needs a bell.

What I don't understand is why the instruction manual and every how-to I read (including the one on this site) tells you to be sure to mark the wires that go to the bell system so you can attach the correct one to the transformer terminal.

Does it really make no difference which wire gets attached to which terminal?

--Matt

 

The diagram you displayed showed a "bell" with two wiring terminals. You apparently have a "chime" with 3 wiring terminals. As I tried to explain before (I think, but I'm not going back to reread the thread), with a 2-wire bell it makes no difference which wire goes where. The button simply "breaks" one of the wires to the ringing mechanism - it doesn't matter which wire you break. The output on your transformer is 16 volts. When you apply 16 volts to the bell it rings. If you applied 16 volts to the bell all the time it would ring all the time (until it burned out because it's not made for continuous ringing). Pushing the button merely completes the circuit. If you had a 2-wire bell (as shown in your diagram) instead of a 3-wire chime, you would not have one of the terminals marked "T".

When you have a 3-wire chime, one of the terminals to the "chiming mechanism" needs to be directly connected to the transformer. The other side of the transformer is run through the buttons. When the Front Button completes the circuit, the chiming mechanism is "excited" in a way to provide a ding-dong. When the Rear Button completes the circuit, the chiming mechanism is excited in a way to provide a ding.

Since the "T" terminal is required to allow both functions to operate it is important to wire the chime correctly. If it is not wired correctly, nothing will be damaged but the chime would work only for one function. I.E. if you put the direct wire on the "F", the front button on the "T", and the rear button on the "R", then you can only complete the circuit with the Front button. If you are only using one of the two possible functions of a 3-way chime as you are, it doesn't matter how you hook it up as long as you use the "F" and "T" terminals OR the "R" and "T" terminals. Move the wire from the "F" to the "R" and you will have a different ring.

Sorry to be so long-winded in my explanation. Maybe you can muddle through it.

 

This is exactly the explanation I was looking for. Indeed, I do have a three wire chime but as we do not have a backdoor that needs a bell, it will only be used for the front door.

According to your explanation and given my use of the chime for the front door only, it appears not to matter which wire is attached to the "T" terminal.

Thanks so much for muddling through this with me.

--Matt