ECN Forum Forums General Topics of the Trade General Discussion Area Momentary switches/low volt lights

Was asked to look at an old (1950's) resi lighting system that the cust. says has
momentary rocker switches w/relays-transformer at the fixture. I have no experience w/ this.Any info will be appreciated.

Sounds like the good old 3-wire low voltage relay control system. Despard 1PdT center-off momentary rocker switches, load relays with low voltage control. It is still available today, but not too commom.

The relays are GE (there are probably others), the switching end goes in the outlet box, the low voltage control end is outside the box. The relay has an open coil and a close coil, both coils share a common return wire so the result is a 3-wire control.

A few years ago we installed some large 277/480 panelboards (GE) which had extra large wireway space which included a bunch of the exact same GE relays, only these relays were controlled by the buildings automation system. It actually was pretty cool.

We have a neighborhood nearby which was largly built in the 40's and these homes commonly have this type of switching. The local Ace Hardware store carries the relays and the switches and gouges badly for them (like $25 for a little despard switch and $50 a GE relay).

If I get time later I'll sketch out a schematic or find a link to more information. Who knows, maybe there is something here in the tech reference area.

Radar

Radar has it 100%, and here's some more.
GE still has the parts available.
GE Supply; if not at a local branch, the whse had stock a while back.

Some of the homes around here (Northern NJ) used these systems, & there's a lot still around.

Some houses have/had a "master" control to operate most or all of the LV switched lighting from the 'master bedroom' or other locations.

The reason for the system was that LV wiring was cheaper to install then BX or early NMC, and you could control lighting from as many locations that you ran the 3 wire LV to.

I still have a few parts in our shop, if you can't locate them.

John

Out here we have touch matic, sounds like the same thing. LV with lots of bell wire and relays. The biggest problems we have is someone tried to "fix it" an burned up all the relays. Parts are getting harder to find. Rod

General-purpose relays which will do the job are still easily obtainable. If all else fails, it wouldn't be hard to build a complete new control unit to use with the existing wiring and switches.

Might cost the customer a good few bucks though for the custom-made control box.

I was able to find some wiring information at this link:

http://www.dseymour.com/pdf/111-13.pdf

This is a pdf file that contains a schematic and a wiring layout plus some technical data - you can get a good idea of how this 3-wire LV control thingie works.

I made graphics images out of the schematic and the wiring layout by copying screenshots, but I am unable to figure out how to drop the images into this post. So the best thing to do is to follow the link and see for yourself.

Radar


[This message has been edited by Radar (edited 06-30-2005).]

Note: The link in the post above does not display correctly, but it works OK.

Thanks Radar-that schematic will be a real help.I'll be doing the call tommorow,I'll let you know how it goes.