Today for the first time in my life i came accross a house that was low voltage switched. Never have I seen this before. All switching was done thru low voltage wireing to a large relay box in the attic. Low voltage actuated the relays and 120 volts went out.At first I did not know what to belive. I thought the wireing somehow was connected to bell wire. I was wrong. just wondoring how many of you have run accross this and when was it popular if ever? I was really spooked by this as I never even heard of this? Comments?
Last edited by steve ancient apprentice; 07/17/0707:48 PM.
Low voltage wiring had a brief 'moment in the sun' in the mid-60's ... as the latest word in safety. It was particularly aimed at bath and kitchen uses. It was believed to greatly reduce the risk of electrical shock.
Steve, my neighbor's house across the street from me was built in either '58 or '59 and the entire house has a low voltage lighting control system. My neighbor was building the house himself and was talked into the system as being the newest and greatest thing.
We installed a ton of it when I helped my brother build his house in '93. It kept us from needing several 3 & 4 ways and allowed us to do some On/Off/Time delay Off switching for outdoor lighting. Our relay panel went in the basement though. Joe
In the late sixties and seventies low voltage switching was popular in very high end housing because it could be used top control multiple areas or zones. One low voltage switch could be used to start a sequential relay control motor so that as it slowly turned, it would activate relay contacts that were in parallel with the normally open switches that controlled a specific room or light. I serviced a large estate in the mid seventies that had an extensive low voltage switching system. From a touch of three switches next to their bed, the home owner would start a sequence that would turn on every interior and exterior light in their home and on their entire estate. These were some very high profile people and they didn’t mind spending the money as they felt they needed the extra security. The system was comprised of at least 4 motorized zone controllers and at least 100 relays. Quite impressive for the day.
I remember a General Electric LV control system which was installed in a church built in 1970. The system was used to control the sanctuary lighting. There were 12 circuits, controlled from two locations - the pulpit, and a control room at the rear of the sanctuary (which also contained the Relay enclosure, two breaker panels, 480/277 - 208/120 transformers, dimmers, and the sound system mixer/amplifiers). The controllers had two 12-position dials, one for ON and one for OFF. turn the dial to a circuit number and push to operate - or else hold the dial in and turn it to operate a number of circuits quickly.
Quite a durable system. It still works perfectly, although the sound system had to have a major re-build - lots of hum and noise from all that power equipment nearby.
What would be a complex switching scheme otherwise, becomes a piece-o-cake in a low voltage system. Switching any number of loads on and/or off becomes a simple matter of using a diode matrix. The only limiting factor would be the additive currents of relay coils, exceeding the ampacity of switches or the power supply.
I remember building a couple of PCBs for outdoor lighting control. A tap on the off button caused a several minute off-delay while holding the button for 3 seconds turned the lights off without further delay. I could have just as easily put in a control to turn the same lights on if the dog barked. On a more practical note, those relay boards they sell that connect to a parallel printer port, and a few more diodes, would have added computer control to the matrix. Once you have 3 wires into a 2 switch combo, control possibilities are limited by your imagination instead of the number of conductors. Joe