Modernize Vintage GE 24v Lighting Control System?

Hi everyone,
I have recently purchased a home that uses a circa 1970’s GE low voltage lighting control system.
It consists of 24v power being run from a transformer (at the electrical panel) to various wall switches (which are momentary on/off switches), that in turn switch a relay installed up at the light fixture. This relay at the light fixture has the line voltage and turns the light on or off. The lights are all regular 120v fixtures.

I am looking to modernize and automate this system without replacing any wiring. I think my best bet is to either replace the existing 24v switches with a “smart” equivalent, or have a hidden wired-in module behind the switch or at the fixture to be able to control the light remotely. Any ideas on devices that would work for this? I haven’t been able to find anything.

Also I am wondering if there is a method to “sense” the status of the light, so I can know if a light is on or off?

Thanks in advance for any help you can offer!


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I can’t come up with anything that is ideal but here are some ideas…

ANother solution is to replace your central transformer with lots of e.g. aeon relays… THen you can use the existing switches to switch the relays but they would also work with SmartThings…

or you could replace all your esisting bulbs with Lfix or Hues (or similar)

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My home has this old GE control system for all switches. There are 56 circuits of this system for the house. I wanted to add automation but the available on/off controls aren’t directly compatible. I’m an electronics hardware designer by trade so I designed a small circuit board that connects directly across the existing GE switches and allows me to control the circuit with a “standard” on/off switch which is closed for on and open for off. I’m now using regular dry-contact Z-Wave devices for many of these circuits. So far I’m fairly happy with the system. The existing GE momentary switches still operate along with my SmartThings automation. The one flaw in the system is SmartThings doesn’t report the status of the circuit if I use the old GE switches but the GE switches, which have pilot lamps, do report the status correctly regardless of which control I use. I plan on adding more automation controls as time permits.

An alternate solution for operating the GE system is to use the Monoprice no-name curtain control. It provides a momentary dry contract closure for ON and a separate one for OFF. The contact closures last about one second in the default mode. I didn’t select this method because i feel the pulses are a bit long and, most importantly, you have to provide an external power supply for the Monoprice box. My solution doesn’t require an additional power supply because it “steals” its power from the existing GE circuit. The same lack of feedback would exist with this solution.

I’m fairly familiar with the GE system since I installed it in 1980. It certainly doesn’t offer the versatility of today’s Z-wave/Zigbee systems but it’s served me well since new and it allowed me to do some nice “tricks” as far as controlling the house goes.

DonArnold, I would be very interested in hearing more about your automation setup with GELV if you have time or a link to a write up if you have one.

I too have the GELV and have been messing around with tying it into my Smartthings network. I have the Monoprice curtain relays you mention set up inside of plastic enclosures triggering one of two separate SSR relays (one for on, one for off) to trigger the 24v pulse on or off to three different RR7 relays. I agree that they pulse for too long, in fact I am starting to notice some extraneous wear on one of the most commonly used relays (louder buzzing, sometimes will not ‘latch’), I am sure you know the symptoms). Also having to power them with a separate 12v DC transformer definitely makes it a little more cumbersome than I’d like. Additionally Monoprice apparently no longer sells the curtain module relays.

Im looking for something that I can hopefully tap off of one of the master switches that currently controls 8-10 devices, with option to tie to other switches throughout the house as long as I could get the 24v low voltage wire to it.

If my ‘pilot’ test of three relays did well, I had plans of one Monoprice relay and two SSRs per switch, all mounted inside of a large electrical enclosure and mounted on the wall in my garage (where one of the master switches are). This method would have been decently economical at about $20 to $30 per switch (depending on sale prices) if the relays didn’t pulse for too long, and if they were still available. It would have also allowed me to keep the rest of the system (switches, RR7 relays) in tact.

At $30-$40 per RR7 relay, I cant afford to blow them out at a higher rate than they are normally supposed to last.

Part of me wants to systematically remove the low voltage system and replace with modern wiring/switches but that would mean running 110 lines to all switch plates and I would lose the functionality of the ‘easy’ low voltage control.


It’s nice to hear from someone else who has the GELV stuff. MY house was built in 1980 and has 56 circuits of it. All of the relays are in one location which makes it easier to play with.

I’m an electronics controls designer by trade and an electronic hobbyist the rest of the time. I started playing with SmartThings and wanted to integrate some controls into my house. As you know the real issue is ST stuff is constant on/off vs. pulses. My solution was to design a little circuit board that actually steals power from the GELV circuit it’s controlling and accepts a simple on/off switch for an input. When the switch closes the board generates an ON pulse and when the switch opens it generates an OFF pulse. I’ve used a number of the dry-contact Z-wave modules and I’ve also converted some of the standard hot relay modules to dry contact output. I’ve had these running for almost a year without issue.

The circuit has solid-state relay outputs for the on/off pulses so there are no moving parts. They also don’t care if the circuit being controlled is anywhere from 12-30 Volts AC or DC. Some people use 24 VAC on the GE relays but GE wanted you to use half-wave rectified DC because it makes the relays snappier. I made the input range wide so I could use it for other things if I want.

Here’s what it looks like:

It can be hooked up on the LV switch circuit anywhere because it only uses the on, off and common wires. There is a pair of wires for the dry switch contacts. I wanted to be able to stick it in a regular switch box with a standard switch anywhere I wanted to but so far I’ve only put them in my relay cabinet.

Nothing’s perfect and the down side of this is it isn’t aware if you turn the GE relay on or off with the normal LV switch. I get around that by simply switching to both states with ST and everything syncs up.

Let’s stay in touch. I’m not the sharpest on Z-wave so it’s nice to have someone doing the same thing I’m doing to consult with.



Wow that is very impressive. I am not savvy enough in electrical control to be able to do those or probably even understand them.

Having the relays all at one central location is definitely an advantage I think. My relays are all in the receptacles/boxes at the lights.

I would love to keep in touch to share ideas, even though I think you may be light years ahead of me in terms of understanding the electronics and what options there are to control them.

I was really upset that the curtain controllers did not work out for me. That would have been a fairly inexpensive solution to integrating into ST/Z-wave with somewhat of a compact footprint and little DIY wiring needed. I imagine that something could have been wired up to take that ‘long’ momentary pulse and turn it into something shorter that wouldn’t put so much stress on the relays, something similar to what you describe in controlling a simple momentary on/off switch maybe? Probably a moot point now since it seems they are unavailable anymore.


I’ve tried converting some of the dual modules, intended to go into a switch box with the regular switches, into two-output dry contact modules. It gives me two dry contact controls for a little over half the price of a single module and I can control my GELV using my little circuit board.

The dry contact conversion is quite successful but I’m not really happy with the procedures for using these dual modules as two separate controllers on ST. You have to create endpoints which are phony switches. The one in the picture controls two light circuits in my workshop ceiling. I’ve created an individual virtual switch for each output and used a smart app to give me a third virtual switch which controls both at the same time. I attached a picture of a converted module. You can see the two striped wires coming out of each of the “Load” holes. Each pair of striped wires is a single dry relay. It takes a bit of surgery on the board inside the module but that’s the type of work I do anyhow. Of course the moment you do this you have no warranty on the device.

Having all of my relays in one place is certainly convenient for many reasons. I attached a picture of one of my 24-relay cabinets. There are two of these stacked vertically and a smaller (8-circuit) cabinet just to the side of them. The relays are down the center with LV on the right and HV on the left. There’s stuff mounted in the HV side that technically shouldn’t be there but it’s convenient and there’s no room left to get more wires in or out, especially on the HV side. All the LV wiring is telephone wire, either 6-pair or 12-pair cable because I got it for free.

Tell me more about what you’re trying to do. Do you have any dry contact controllers, other than the curtain module? Maybe I’ve done something that can help you. At the moment I’ve got about forty devices on my hub. They’re not all lights or doors. I sense stuff and send alarms etc. I use geo-fencing from my phone presence detection to control stuff on ST. It’s all great fun and a learning exercise which is what I want.


Thank you for the reply and the pictures. At least it looks like the electrician who installed that did a halfway decent job of keeping things a little organized (I’ve seen worse rats nests when searching for GELV on the web).

My end game goal is to be able to get all of my house lighting incorporated into smartthings. Or at least the ones that make the most sense to be automated (for example my bedroom closet light is switched with GELV, but I don’t have an absolute need to control that with ST).

I currently have about 60 hard devices connected to smartthings, about half of those being lightbulbs or plug in/ in-wall switches/dimmers, and the other half being sensors (contact, motion, temp, humidity, etc).

Three of those switch devices are the curtain module relays – garage lights, hallway/steps lights, and whole house fan (my favorite application). They are set up as “Z-Wave Device Multichannel” in ST.

Each of the curtain modules are wired into the GELV system as follows…

12v wall wort adapter powers the curtain module. The curtain module has three different commands. The first is an “Open” command. The second, “Close”. The last is what I believe is to tell the curtain controller to “turn on” (I listed this last, however it fires every single time either the ‘open’ or ‘close’ command is triggered). Each of these inputs triggers a momentary but not instantaneous output.

Since the GELV relay needs a 24v momentary signal from each the “on” and “off” sides of its switch, I have a separate SSR relay for each (one for “on”, one for “off”), that is triggered by two of the curtain module commands as follows:

The “turn on” command set to turn the lights on.

The “Close” command is set to turn the lights off.

I did it this way since the module runs the ‘turn on’ command every single time (no matter whether “open” or “close” command was sent). If I turned the lights on with the “open” (or “Close”) command, there would be a minimal (yet very noticeable, especially by my wife) delay before the lights turned on.

The disadvantage of this is that even if the lights are already off, If ST sends an off signal (e.g. I have a routine that shuts all lights off at 1AM), they will actually flicker on for a split second before shutting back off Not a big deal in the garage or hallway, but wouldn’t work out in the kids bedrooms). Plus this adds extra wear on the GELV relays on top of the already long pulse that the commands send. I’m sure there is a work around flow for this with a simulated switch that can act as a ‘pilot light’, but I havent dug into it too much (plus I don’t think it would be applicable if the manual switches were used).

Note that for the whole house fan I didn’t wire them this way, and instead just tied to the open and close commands. I don’t care if that takes a split second to turn on.

I have all of the components for each switch crammed into a plastic project enclosure (actually an electrical box) with only the 12v power and the on/off/common lines coming out of it. It’s somewhat clean but I would love it to be more well integrated in a single location/large electrical box where I could share the same power supply (and maybe even 24v common wire) so that I would only need to tap into the GELV switch wires. I have probably 15 to 20 additional GELV lights that I would ultimately like to control.

The hallway/steps light is the one that has ended up with a bad RR7 relay (which I had previously replaced not too long ago). It was the one that was fired the most from ST (I had it set to turn on anytime someone came home, anytime motion was sensed in the hall, and anytime the top of steps door was opened, and off after 5 minutes). I have the other two still hooked up that way without noticing any issues yet.

Sorry if that was all too rudimentary of an explanation. Like I said, I am not an expert on this stuff, part of the reason I wrote it all out was so I could understand it as I was typing. Actually after re-reading it I wonder if I could modify the ST device type code to tell it to pulse quicker and also not to run that ‘turn on’ command every time…


I’m confused as to the need for the solid state relays. The Monoprice curtain control has two wires out for each open, close and start. These are isolated relays that can connect to the 24 Volt GELV switch circuit directly, using only three wires. Why use the SSRs?

As for the failed RR7, my experience over the last 37 years is that 10% of those relays fail early in their life. Once you get a few years on them they tend to last forever. I’ve still got lots of original relays in service after 37 years. Actually I use the RR8 (which is discontinued) or the RR9 in my system. These have an extra set of LV contacts for controlling a small light in the switches. The RR8 had an extra (yellow) pilot wire and the RR9 has two extra (yellow) wires. I use the RR9 by connecting the extra pilot wire to the blue coil common. I buy whatever I can find on eBay because they’re too expensive to buy new. Most of the relays that go bad fail either in the ON or OFF position. They turn ON and won’t turn off, for example, because the OFF coil is open. I’ve successfully repaired a few of these.

Your scheme, with the stuff in a box and only the 12 Volt power and relay controls coming out, is a clean solution. The way I run mine requires I power the dry-contact modules from line voltage. I usually put a cord on it and plug it in. The two contact wires simply go to my little PC board, wherever it need to be located. My little board has three wires to connect across the GELV switch and two LV wires that come from the Z-Wave module. The LV side doesn’t require a power supply because it steals operating voltage from the GE relay.

I attached a PDF drawing that I made for one of the guys I work with who also has some GE stuff. He was curious about pilot and locator lights and making switches interact, for example one switch turns several things off but not on. Since I built my own LV cabinets my 24 V supply has a center-tap so I can pick off 12 Volts to make the pilot lamps glow dim as locator lights. When you walk into a room the glowing switch will turn the lights on.

If you find a dry contact Z-Wave module, I’d send you one of my boards to play with. You might find them useful. You can actually use it to hook the LV switches wires to a standard toggle switch.

I have several automations that use a motion detector to do something, like ring a Z-Wave doorbell when someone walks in the garage. I also use the ST phone presence detect function to turn my water leak prevention valve to away mode when no one is at home and turn it back to home mode if any one arrives. That sucker operates quit a lot.

One last comment… You can write your own device handlers. I’ve borrowed a couple off of GetHub but I’ve not invested the time to really learn the programming, though I’ve successfully modified a couple. I write in Assembler and imbedded C so Groovy is another language to learn. You’re supposed to be able to set the time periods for the Curtain module. It defaults to one second but, as I understand it, you can set it to whatever you like. I’ve not investigated how to do that. I also want to learn how to pass values to my Aeon doorbell so I can have different switches announce events. You’re supposed to be able to have 100 sound files and select what you want to play from the Z-Wave input. It’s just another goal I don’t have time for.

I enjoy the chats.



Sorry for the delayed response. I truly enjoy the discussion too.

The curtain module I have has only one wire each for open close stop. The wiring diagram is as follows:

From the manual these wires can only handle 100ma max. I think I have read that the GELV pulse is about 300ma. Plus the module runs at 12vdc and I need to be at 24vac for the GELV. That’s the reasoning I went with SSRs. The curtain module closes a loop on the 12vdc input side which triggers the 24vac loop to close. If there is another way to do it I would appreciate your input (even though it may be a moot point since it seems I cannot find these anymore).

Regarding the 10% bad relays, that actually makes a lot of sense in my situation. The relay that is now bad has been “loud” ever since I put the thing in (even before ran with the Z-Wave device). I’m sure you know what I mean when I say loud. It is now failing in the ON position, as you describe, the off coil will latch only every once in a while (I tell my wife it needs to ‘charge’ up). Maybe I will give it a shot with another relay, and lesson the amount of automated on/offs it runs.

I think the pilot light GELV setups are great and you could do some real cool things with them if you could figure out the z-wave coding side of things and/or found (built?) the right device. Feedback to ST of whether switches were turned on/off manually is one. Unfortunately my system is not set up with pilot switches. My house was built in 1954. From my research GELV was just beginning to be used at that time in high-end residential applications and maybe the pilot set ups just weren’t around yet. The original owner of my house was a successful doctor and I can see that he made decisions to go ‘all in’ on GELV so I would be surprised if he decided against the latest and greatest technology. I am pretty sure that every switch that was originally installed in the house was GELV (even closets, garage, exterior lights). But none have pilots and they weren’t even wired with an extra pilot wire for future compatibility.

I am not sure how to find or open the PDF you mentioned, maybe it did not upload?

I appreciate the offer on you sending me one of the boards. I will let you know if I get the gusto to get back into tinkering with this project some more and get a hold of some dry contact switches. Right now, the money just isn’t right for me to go all in on these things. I’d like to be below $20 total per switch (ideally closer to $10-$15), and preferably it needs to be something that is a bit more ‘out of the box’ ready. ST has been fairly reliable but the times that it is down or not working correctly has me really questioning how much I’ve already put into my smart home. I buy the devices when I can find them at deep discount (clearance racks, online sales, etc). To me the retail prices are just too much right now. At least with the light bulbs and switches I could sell them off for what I have into them (or maybe more) if I wanted to. When I start homebrewing devices they are basically instantly sunk costs unless I can get them to a ‘plug and play’ level that can be used in the future by others.

I have glanced at the device handler code in the past for the “ZWave Device Multichannel” to see if I could modify the time periods and maybe even get rid of the “turn on” (its actually referred as “Stop” in the manual, Ive been calling it the wrong thing this whole time) command when I want the lights off, but I am admittedly not up to snuff on understanding the code enough to be comfortable modifying it. I took C++ in high school and that was a long time ago.

In regards to the voice feedback, have you taken a look at LANnouncer? Its a little bit of a workaround but I have my house set up to speak through an Amazon Fire tablet whenever any of the exterior doors are open/closed, the alarm setting is engaged/disengaged, and whenever our presence sensors come home (my oldest gets a kick out of “The greatest dad in the whole world has arrived” notification when I get home). It could easily be used to do what you want in terms of announcing different switch/sensor events.

I have the Fire tablet mounted to a wall in between our kitchen and dining room and leave Smarttiles website (another thing to look into if your going to do the tablet thing) running all the time. It comes in handy when we have to have a babysitter at the house so they can control the lights (although they usually just end up turning them off from the hard switches in frustration or calling me and asking if I can turn the lights on for them via my smartphone).

Hey guys you seem to be a lot smarter than me. Could we replace the expensive RR7 relays with this from wish.