Identifying Old Doorbell Wiring

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  #1  
Old 06-17-12, 07:39 PM
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Identifying Old Doorbell Wiring

Our home currently has a wireless doorbell which we hate. In re-siding the house and replacing the front door, our contractor found doorbell wiring for the button. We subsequently also found a transformer in the basement. However, we can't figure out where the chime used to be installed.

The wires in the door are reading hot with a non-contact voltage tester, so I believe that the prior owners tied the wires together in the wall before they patched over the old chime. From what I can figure, with what we've found so far, we could probably install a bell in the basement and have a wired doorbell, but I don't think I'll be able to hear it from the 2nd story. What I really want is to figure out how to install the chime in my entry way, where it used to be installed.

Does anyone have any suggestions (other than ripping apart my newly painted walls) for identifying where the chime used to be installed?

Thanks in advance.
 
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Old 06-17-12, 07:59 PM
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Run all new wire to the front door, the transformer, and the chime. There is a very good chance that the insulation on the old wiring came off and shorted the system. That's probably why they installed a wireless.
 
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Old 06-17-12, 08:32 PM
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Yeah, it definitely hadn't occurred to me that there might be a short. The prior owners did some weird things with electricity (installed a switch without a box, removed a ceiling light fixture and plastered over it while leaving a hot connection in the box, made most of the junctions in our attic without bothering with junction boxes) so I just assumed they didn't like the doorbell and didn't want to do the work of installing a new wired one. I guess I'm back to square one with this...

Thanks so much for your help!
 
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Old 06-18-12, 05:24 AM
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You can test for a short with a multimeter and test if the button wires run to the transformer then just run new wire to where you want the chime.

The wires in the door are reading hot with a non-contact voltage tester
Meaningless given their unreliability of that type of tester. Sometimes you will get false positives. You need a multimeter for meaningful testing. With the meter set to ohms between the wires from the button there should be ~0 resistance (continuity) with the button wires connected together at the door and infinity with them not connected at the door. In both tests they would not be connected at the transformer during tests.
 
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Old 06-19-12, 06:15 AM
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A long wire with clips on both ends (which you can stretch across the floor or up stairs) can come in handy for testing continuity of a wire hidden in the wall or for testing voltage.

Always turn the power off before testing continuity (resistance; ohms).

Also, for testing continuity, at least one of the two items you touch the meter probes to must not have anything else connected to it. For example when testing continuity from a terminal screw to some other object or wire, label and remove all the wires from that screw before testing.
 
  #6  
Old 06-19-12, 01:25 PM
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As always, photos are helpful. How many conductors are in the cable at the door? How many cables do you see at the transformer? How old is the house? Is it lath on plaster or drywall? Is there a side door or back door that might also have had a doorbell button?

What is the type of cable, i.e. 18 AWG thermostat wire, twisted pair communications cable?

I've had luck using a low-voltage tone tracer with a split pair or thermostat wire, to locate subsurface wire at a depth of up to 1-1/4".

Have you removed any grilles, looked in the attic? How far from the transformer can you trace the cables?

Whenever someone says "short" I figure they might mean "open". A sustained short would probably burn out the transformer, but an open would just cause things to stop working.

You need a $10 meter and some basic understanding of logic and circuits to troubleshoot this.
 
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Old 06-19-12, 02:40 PM
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Whenever someone says "short" I figure they might mean "open". A sustained short would probably burn out the transformer, but an open would just cause things to stop working.
When I suggested that the wires were shorted, I didn't mean from from hot to ground, but from one side of the switch to the other. That would make the bell ring continuously.
 
  #8  
Old 06-19-12, 03:23 PM
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When I suggested that the wires were shorted, I didn't mean from from hot to ground, but from one side of the switch to the other. That would make the bell ring continuously.
That is possible however I have seen it twice with different symptoms and results. I suspect it happens often but is rarely analyzed carefully.

In both instances, there was an electromechanical chime. The solenoid remained energized, presumably holding the plunger against the chime plate continuously but making no noise except a faint and not troublesome buzzing for a while, as reported by occupants. I found the insulation on the solenoid windings melted, and the transformers dead.
 
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