Home wiring question, relay/low voltage system! [Archive] - Chevelle Tech

: Home wiring question, relay/low voltage system!

May 5th, 09, 3:51 PM
Ok guys, I have a question for the electricians in the house. I have a relay system in my house installed by an electrician that previously lived here. I have low voltage small gauge wire going down to the switches, and jewel boxes full of relays up in the attic.

Well as time goes by, the relays go out, and they always go out in the "closed" position, so whatever was switched by that relay stays on perpetually.

There are typically more than one of these relays in close proximity, and its nearly impossible to track the original wiring under the spray-in insulation that was added years after. These are Remcon R-115S type relays that use the momentary switch. All the switches you push in the house are up to turn it on, then it returns to the neutral position in the middle, of course down to turn it off.

Any guidance on the best way to track down which ones are out would be a huge help. I have 3-4 of these things that i have been dealing with for a while or just working around, but its getting to be a pain... The lights in a spare room, lights in a hallway, a garbage disposal outlet, and now my porch lights.

Thanks for any direction on this guys, the relays themselves are expensive enough to replace ($40 a piece) I want to make sure i'm replacing the right ones.


May 5th, 09, 5:22 PM
This would be a tedious process, but here goes. Pull/disconnect all relays but one. Try the various switches and see which light comes on. Repeat this for the others by installing on relay at a time. This low voltage switching system is new to me; what is the purpose of doing it this way?

May 5th, 09, 7:37 PM
No idea what the purpose is. Apparently its a common situation in industrial application where you dont want the full voltage of a huge system going through a manual switch someone is going to be throwing, so you have lower voltage system controlling a relay that handles the juice.

Now why someone would install that in a residential home, i have no idea... but its what i'v got.


May 5th, 09, 9:42 PM
First of all, someone sold you a bill of goods:yes:. Second of all, if they sold you said bill of goods, they should have had the foresight to locate the relay panel in an accessable location for maintenance and labeled the relays:sad:.
That being said, the best way to find the problem relays (as you explained, they fail to the on position) is to get two cell phones and unplug them one at a time and see what turns off. Does your Garbage disposal run all the time or have you disabled it?
You can also phone out the wires and label them and make life easier for future problems. Not going to be a pleasureable task in warm weather. Best of luck :beers:.

May 5th, 09, 10:25 PM
Oh my God. I don't know if that's how they do it in California, but I think if an electrical inspector saw a set up like that around here he would be licking his chops and running out of ink in his violation-writing pen. It sounds to me like a guy who had just enough smarts to figure out he how could reduce his electrical bill by a few bucks, but didn't plan out the whole thing too well. I don't envy you. I make a living out of creating and trouble shooting low-voltage electrical systems, and I sure wouldn't want to do it in my own house for free.

May 6th, 09, 3:10 PM
So J, you sound like you might be able to help me then. What is the best way to track down one of the blown relays? I have no idea when this was installed, for all i know its 20-30 years old anway. I'v had thoughts of rewiring the house with a new wiring system, but i would need to learn a few things before I could undertake that myself, and trust I wouldn't burn my house down.


May 6th, 09, 4:22 PM
I'll give it a shot. First of all, I found an instruction manual online for these relays. Look at page 6 for some trouble shooting tips.http://http://www.tequipment.net/pdf/Remcon/R-115S.pdf

The cool thing about this system is that the low side is very safe to troubleshoot because it carries very little current. Get yourself a multimeter and you can test away.

Probably the most direct way to find the relay you are looking for, is to go directly to one of the relays, disconnect the side going down to the switch (The low votage side), put your meter on the lines going down to the switch. We're going to check the continuity of the switch, so set up the meter for ohms (that's the funny little greek symbol. I don't mean to be elementary, but I just don't want to assume). The meter should read infinite ohms or out of range to indicate an open circuit if the switch is off. Have someone start flipping/pressing the light switches until the meter reads 0 ohms, or very close to 0 ohms. I guess this could work both ways. If you tap into a switch that is already on, you would show a dead short then it would show open when the switch was tripped again. With a digital meter, give it a second or two to register with each try of a switch. When the meter goes to 0, or vice versa, you found out which switch that relay is associated to. You can do this for each relay that you can find. I would write on or near the box with a sharpie what switch it is connected to for future reference so you don't have to do all this again.

Some multi meters (probably most) have a function for checking diodes that will actually give you an audible tone when the probes detect a short. I use this a lot so I don't actually have to watch the meter. The meter might have a symbol on it that looks like an arrowhead with a line going through it (the electribcal symbol for a diode) and maybe it might show some sound waves coming from it to indicate the tone.

Here's that link again in case I goofed it up above: http://www.tequipment.net/pdf/Remcon/R-115S.pdf

Good luck. I'll check back and see how you did.

May 7th, 09, 3:24 AM
I glanced at the pdf linked by J above but didn't read it too closely so don't listen too closely...

As a "quick" (depends alot on how many relays there are) check, consider having someone turn things on and off while you feel one or two relays to see if they engage/disengage. A relay typically makes a click noise that you should be able to feel with your fingers. Use both hands, each on a different relay. Initially, use small yellow office "stickies" to label the relays while the other person takes notes or uses similar labels. From this, build a map or table of which switches/relays control what.

This gets easier after each test, since the number of switches/relays/circuits is reduced after every test.

Make a sketch of the physical location of each relay and label it based on the stickies. Number the relays on the sketch and physically.

Once you've isolated the relays that do work, you can add the ones that don't to the table as unknowns. Then replace a nonworking relay and test the nonworking switches to see what circuit starts to work. Add the now working switch/relay/circuit to the map/table. Repeat until everything works and never lose the table.

If you can't feel the relays engage, you need to test them by for example measuring the voltage across the coil.

This is of course tedious but once done, its done forever until the wiring fails. X switch doesn't turn on Y lights? Table says Z relay.

Why the relays fail and leave the device/light on is a question. Were the relays wired to use normally closed or NC contacts, even though it makes little sense?

I've subscribed, so if you want to chew me out for such a simplistic approach, feel free :)

Good luck!

May 7th, 09, 7:57 AM
I thought of Kev's suggestion of feeling or listening for the audible "click" at first, but when I looked up the Relay online, I discovered that it is a solid state relay. You probably will not be able to feel or hear any sort of click when the relay trips. Mechanical relays have a coil and a wiper and there is no secret when one is energized. You would hear the click without a doubt.

Since these are solid state, you wouldn't be able to open on eup to check the voltage across the coil. There is no coil.

I agree with the mystery of a relay failing and leaving a light on. I would think if a relay failed, it wouldn't turn something on. Like Kev said, maybe the relay was wired NC (Normally closed as opposed to normally open). Maybe the problem lies in the switch and not the relay? The continuity check described above should pin it down.