Help with old low voltage switches

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GerryB

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woodbridge, ct. USA
The HO has two lights in a dressing room controlled by 3-way touch plate switches. He said they died after a while of working where he would push the switch many times to get them to come on. I tried tying all the switch wires together and nothing, although I did see a little arc which I though I might not see if the relay was bad. He has 16 relays in a box in the basement. Would one relay be used for just two lights? Each 3way has a single pole in the plate with it for different lights that are working. Also is there an easy way to find which relay is for these lights. The bulbs are ok, I didn't take the fixtures down to see if anything came apart, but now I am thinking since I saw that arc maybe it has nothing to do with the low voltage. Thanks for any input ahead of time.
 
GerryB said:
The HO has two lights in a dressing room controlled by 3-way touch plate switches. He said they died after a while of working where he would push the switch many times to get them to come on. I tried tying all the switch wires together and nothing, although I did see a little arc which I though I might not see if the relay was bad. He has 16 relays in a box in the basement. Would one relay be used for just two lights? Each 3way has a single pole in the plate with it for different lights that are working. Also is there an easy way to find which relay is for these lights. The bulbs are ok, I didn't take the fixtures down to see if anything came apart, but now I am thinking since I saw that arc maybe it has nothing to do with the low voltage. Thanks for any input ahead of time.
Click to expand...

Since you saw that arc in the switch chances are the relay coil is still a complete functioning circuit -what is not happening is contact transfer in the power circuit. Still need to find the correct relay and replace it though. Having to push the switch many times to get it to come on makes sense also, it was failing to make contact then but has finally gotten to where it won't make contact at all for whatever reason.

Finding the right relay - maybe connect a circuit tracer but grab a "hot" from someplace else and connect to the neutral from the controlled light in question. Then you can at least trace the neutral back at the relay box find out which cable you are dealing with and trace the hot to the correct relay.
 
I would think its a possible contactor problem if you by passed the switch and still no lights. I would locate the contactor and see if power is passing through. Maybe the coil is bad.
 
yes it sounds like the relay

but if button is sticking it might do that. i would include taking button loose and touching wires together as part of standard troubleshooting on these.

and if controlled at more than one place, all buttons would have to be disconnected
 
readydave8 said:
yes it sounds like the relay

but if button is sticking it might do that. i would include taking button loose and touching wires together as part of standard troubleshooting on these.

and if controlled at more than one place, all buttons would have to be disconnected
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If you suspect that a button is stuck, wouldn't a simple voltage check at the relay coil be easier than disconnecting all the buttons?
 
When OP said: "I tried tying all the switch wires together and nothing, although I did see a little arc which I though I might not see if the relay was bad" that arc was because current was flowing in the switch loop when contact is made. Control circuit is likely good, control source and relay coil is likely good, just appears to be a problem with the power circuit side of things.
 
150819-2345 EDT

I posted a reply around 5 PM and it is not here. I will not try to reconstruct my previous comment.

There is a very logical procedure to troubleshoot this problem. But you must have knowledge of how this circuitry works. Go find an old discussion on GE RR relays, circa 1960.

It looks like it might be GE RR type relays, but a very sloppy installation. $60 is too much for a replacement.

A well designed installation can be very reliable.

.
 
gar said:
150819-2345 EDT

I posted a reply around 5 PM and it is not here. I will not try to reconstruct my previous comment.

There is a very logical procedure to troubleshoot this problem. But you must have knowledge of how this circuitry works. Go find an old discussion on GE RR relays, circa 1960.
Click to expand...
That's too bad. I would have liked to have read it.

It looks like it might be GE RR type relays, but a very sloppy installation.
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I have only worked on a few of them, but each of those few looked a lot like the picture.
$60 is too much for a replacement.
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'bout what I paid the last time I bought one.

A well designed installation can be very reliable.
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I agree. The one I have worked on have been in service for fifty years, and I don't get to work on them much because they keep chuggin' along without much attention.
 
Built own house 42 years ago, RR3 relays (53 of each) and a few hundred switches and more logic diodes than that. Many relays controlled by combination of up to 10 switches. Maybe one of these slow retirement days I'll convert the whole thing to USB control?

Every time (4 times in 42 years) I thought I had a bad relay it was the switch or the power source.

One was a switch above a counter top in my shop that had a signal generator shoved back against an outside light switch - spent 15 minutes finding why the outside light would not turn off

2nd was a loose connection of the rectifier on the class 2 xfmr output.

3rd was failed big electrolytic cap on the 24vdc control supply (put a 0.02F big cap on line and class2 can drive all the relays at once, no need for the old GE sequencing switch to turn all house lights on or off at the same time)

4th was when then teenage son threw a dart across the basement and missed big time, hitting a switch and shorting it out and not telling anybody - a case where light would not turn on.

The little arc you see in the switch is there when new, common and OK.

BTW, in 1972 RR3 were all of $2.59 each at Graybar. Last I looked the typical trade price (RR7) was over $20. The $60 OP saw is a real ripoff.

edit PS: I found at the time it was better for control logic and wire use to put the relays in the fixture boxes - bigger boxes but no big relay cabinet like OP photo.
 
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junkhound said:
Built own house 42 years ago, RR3 relays (53 of each) and a few hundred switches and more logic diodes than that. Many relays controlled by combination of up to 10 switches. Maybe one of these slow retirement days I'll convert the whole thing to USB control?

Every time (4 times in 42 years) I thought I had a bad relay it was the switch or the power source.

One was a switch above a counter top in my shop that had a signal generator shoved back against an outside light switch - spent 15 minutes finding why the outside light would not turn off

2nd was a loose connection of the rectifier on the class 2 xfmr output.

3rd was failed big electrolytic cap on the 24vdc control supply (put a 0.02F big cap on line and class2 can drive all the relays at once, no need for the old GE sequencing switch to turn all house lights on or off at the same time)

4th was when then teenage son threw a dart across the basement and missed big time, hitting a switch and shorting it out and not telling anybody - a case where light would not turn on.

The little arc you see in the switch is there when new, common and OK.

BTW, in 1972 RR3 were all of $2.59 each at Graybar. Last I looked the typical trade price (RR7) was over $20. The $60 OP saw is a real ripoff.

edit PS: I found at the time it was better for control logic and wire use to put the relays in the fixture boxes - bigger boxes but no big relay cabinet like OP photo.
Click to expand...
What do you do in your spare time?
 
ActionDave said:
What do you do in your spare time?
Click to expand...

You mean the 5 or 6 hours I wasted in 1986 going to the last time I was in a movie theater see 'Dune' with the kids and the last 'lost cause' Mariners ball game I went to in 1992 ?

Actually, when in 20's never could figure out why everybody did not save themselves lots of $$ and design and build their own house or do it just to get what they wanted at an affordable price. Took me till 20 years later to finally realize 95% of people are either 'lazy' or not too bright ?

The electrical was the easiest part of that house <G>
 
150826-2345 EDT

GerryB:

If you have the defective RR7, then check to see if either coil is burned out. A simple resistance measurement will tell you. I measured about 50 ohms per coil.

If both coils are good, then try a momentary 24 VDC to see if you can change the relay state. Do not apply continuous power to either coil. 24 V and 50 ohms is about 12 W. The coil can not stand this amount of power very long. Minimum DC voltage to change the relay state may be less than 18 V. Minimum voltage on AC will be somewhat different than DC.

If you find that one or more coils were open, then it is because there was a stuck closed controlling switch causing a coil to burn out.

Proper circuit design can prevent coil burn out even with a stuck switch.

.
 
gar said:
Proper circuit design can prevent coil burn out even with a stuck switch.
Click to expand...
Can you elaborate? I can imagine a device upstream responsible for changing a constant signal to a momentary signal, but couldn't it get stuck too? Or maybe such a device would be more reliable than a switch.

Cheers, Wayne
 
150827-1223 EDT

wwhitney:

There are probably many ways to do this for "one skilled in the art" (Patent Office term).

How I would perform the function today is probably different than what I did 50 years ago. In my home I have about 50 RR relays, and I have had a few switches get stuck, but never a failed relay coil. My old method used a resistor and capacitor. This was extremely simple and reliable.

I have had a few relay failures where the relay would fail to remain latched, or where this problem was temperature sensitive. Some of my relays are in the attic, and some in the garage where there are extreme temperature changes, from over 120 F and below -10 F. But these extremes are very unusual. More typically the extremes would be 0 and 110.

.
 
gar said:
150826-2345 EDT

GerryB:

If you have the defective RR7, then check to see if either coil is burned out. A simple resistance measurement will tell you. I measured about 50 ohms per coil.

If both coils are good, then try a momentary 24 VDC to see if you can change the relay state. Do not apply continuous power to either coil. 24 V and 50 ohms is about 12 W. The coil can not stand this amount of power very long. Minimum DC voltage to change the relay state may be less than 18 V. Minimum voltage on AC will be somewhat different than DC.

If you find that one or more coils were open, then it is because there was a stuck closed controlling switch causing a coil to burn out.

Proper circuit design can prevent coil burn out even with a stuck switch.

.
Click to expand...
You know the HO called me last night and said one of the switches wasn't working in the on position. There are two switches controlling these lights, one working fine the other will just turn the lights off. Tech support says it sounds like the switch and I can easily check it by touching each wire to the common (3 wire system) and one should be on the other off. But maybe as you say the switch could have been stuck in the first place and burned out the relay. (He said before it stopped working completely he would hit it ten times to go on). I do still have the old one so when I have time I will try yo check it out. I just called the HO and told him try not to use that switch, it might burn out the new relay.
 
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150827-2236 EDT

GerryB:

A GE low voltage switching system that does not have some sort of energy limiter will almost certainly burnout a relay coil if a switch is stuck closed. The GE RR relays are quite good, but the switches were sort of junk when I bought mine. Spring return to center was too weak, and for what was in the switch it was way over priced.

This type of system is logically great for any application where you need multiple switching locations. I have five locations from which I can control my kitchen lights. My orientation of switches is such that UP is always ON, and OFF is always OFF. Thus, I don't need to go into my garage to make sure the lights are off, same for the attic and basement. I just push the switch down, but also one can use an RR relay with an auxiliary contact to indicate its state.

.
 
two switches controlling these lights, one working fine the other will just turn the lights off

that says it is NOT the relay. I have had switches in the basement where it is higher humidity that get enough of an oxide coating on the RR type switch contacts (simple phosphor bronze strips touching each other) that the 'switch doesn't work'. Pressing harder sometimes works, but easiest is new switch;

OR, if you are really cheap or if it takes longer to go get a switch, take 3 minutes to pop the switch apart and sand (clean) the contact area clear of the green oxide. (assuming you have emery cloth or steel wool or wire brush or small file handy, or even a few drops of ferric chloride?)

The case I mentioned with the shop equipment leaning on a switch was at least overnight till I got around to trouble shooting - no relay or switch damage -- my 24V supply is a small 30 VA doorbell transformer - with a diode bridge after it and a 100,000uF cap to supply the oomph for more than 2 relays at a time. The RR relays work for either ac or dc.
 
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