A Merry Christmas to all!
Anybody have experience with old (like close to 50 years old) low voltage lighting control systems?
I recently got a call to troubleshoot a light fixture in a church (built in '57). There are six fixtures, switched in pairs (front, middle, and back, with the back switch also controlling several 4' lay-ins in the choir loft). One of the two back hanging fixtures doesn't work. I'm told that it gradually quit working. Jiggling the switch would get it to go on, then it wouldn't work at all.
The fixture is a huge hanging lantern, with 8 CFLs (4-pin base).
I first checked the switch, mainly because it's at ground level and the fixture is 15 feet up and the canopy about 32 feet up.
Switches for the three banks are despard-style, three in a SG box. Open it up and lo! despard switches, all right, fed by a 19-conductor, 20 gage cable (marked "Bryant control cable"). Voltage across the switch (when off) is 27 VAC. Current in the circuit for the operating banks fo fixtures with switch on is about 0.2 amps. I'm thinking that there's a good old ice cube relay somewhere that's failed.
O.K., so my mission is to find the bad relay somewhere. I look everywhere for a control panel and can't find anything.
I get the church maintenance man to move some pews and bring in the scaffolding w/tilt-up ladder w/tiny platform at top.
Up I go. No power at the fixture. So, it's up to the ceiling, at 32 feet. The platform is very moving around like a leaf in the breeze. I'm hoping that the parishoners in the church are including me in their prayers.
There's no relay in the j-box, and also no power present. As long as I'm up there, I re-make the splices of building wire to fixture wires.
Back down at the switch box, I bypass the switch for the non-functioning fixture and get no results. I re-make the splices on both sides of the switch (four conductors on the load side of the one switch, and 11 spliced together with a pigtail to each of the three switches, on the line side).
Operate switch--and lo! All fixtures come on, including the one that wasn't working!
I figure it was a bad splice, so turn off switch, turn on again, and nothing!
I figure it's a failing relay. When I get back to the site, I intend to find the circuit supplying power to the system, cut power, and use a Harris T90 (poor man's TDR)tto find length of wire from switch to relay and to power supply), and a wire tracer to try to find the relay.
I'm wondering if the relay might be in one of the other fixtures (maybe the lay-ins?), but the distance measurement ought to help sort that out.
Anyone have any experience with this sort of system?
Do you think I'm barking up the right tree?
Any suggestions?
Best regards,
Cliff
