Lights turning themselves on (Ghost in the machine)?

[csr0831]

Gentlemen….
Have a slight problem that perhaps one of you can help me with. First, some particulars. The house is about 60 years old and the wiring is all in armored cable (Greenfield?). My outside flood lights can be turned on from 5 locations, which as I understand it means two three way switches and three four way switches. 20A circuit. I am powering about 3300 watts of lights. They are operated by a relay which is controlled by the switch circuit because the power requirements are too high for a 20A circuit. The switch circuit and the lighting circuit are on separate circuits each controlled by their own breaker.


Now for the problem... the other morning I was walking across the front yard and I noticed the outside lights were on. There was no one else in the house so I knew they had not been turned on either intentionally or unintentionally. I went back in and no matter what switch I throw, they stay on. If I kill the power to the switching circuit at the circuit breaker, they go out. Am I correct in assuming that one of the switches in the circuit has somehow gone closed. Maybe from wear and tear over the years something inside broke and it closed? If so, how do I determine which switch it is without replacing switches one at a time until they work? With the age of these wires some of the insulation has become frayed (seems to be some kind of woven or fabric material) and I have had problems in the past with it separating and the wire coming in contact with the metal boxes….which um…sometimes causes an issue…

Anyway, sorry to have rambled…..any suggestions would be welcome! Thank you!

Chris

[jadnashua]

If turning off the power that controls the contactor (i.e., it's coil control) de-energizes the relay, then, yes, you have a problem in the switching circuit. As to how to isolate it to a particular switch, that could get harder. First thing I'd probably do is flip each one and see if they 'feel' proper. On older switches, sometimes you can feel or hear that they are not switching properly.

I'd consider updating the switches to something from X10, or Insteon - i.e., one of the remote controlled type of switch. Also, Lutron's Maestro switches (I know there are dimmers, not sure if they make on/off in this series), uses a much simplified multi-switch wiring, and might be a replacement possibility. Those can handle up to 8 switches controlling the lights with just 12/3 wire running between them. It uses the third wire as a trigger that is tied to all of them in parallel. One master switch and up to 7 slaves.