Thursday, September 22, 2011

What the heck are these old light switches and how do they work?

I am renting a house from a lady who inherited it from her parents. I don't think that they changed anything since the sixties, and she hasn't touched the place either. One of the many weird things about it is the wiring. Almost all of the light fixtures are controlled by switches I have never seen before.

They are tiny little square tabs. Some switches have two, some have four, some have six of the tabs. They always stick straight out (ie - they don't stay up or down when you use them). If you push up, it always turns the lights on. Always. No matter how many switches there are. Likewise, if you push down, it always turns the lights off. No matter which way you push it, it always returns to sticking straight out.

If you hold them either way, you can sometimes get the light fixture (in the ceiling, not the switch) to make strange noises. Sometimes buzzing. One light does a high pitched whistle.

Also, in addition from controlling lights in the normal, close proximity, there are switches that control things clear on the other side of the house! In the bedroom, for example, I can control the back porch lights from one of the six-tab switches.

I was wondering what they are and how they work. It seems like there must be a relay behind the light fixture. Mostly, I was wondering if they are some sort of safety hazard that should have been removed 100 years ago.What the heck are these old light switches and how do they work?Yup, that's a %26quot;Smart Home%26quot; (or some similar version, probably installed in the 60's or 70's) and those switches are low-voltage relays. The ones that cause the fixture whistles and humming are also probably dimmers. They were still selling replacement components for this back when i worked in electrical sales in the late 1980's but I doubt they are available now. They are not inherently unsafe but it can be a hassle to replace them since many were installed using a lighter gauge wire than is required for line voltage switching. I would not worry about it safety wise as long as they work. If they start to NOT work, it's the landlady's problem, not yours.What the heck are these old light switches and how do they work?The 'tabs' operate a relay which in turn switches the lights on or off. The buzzing you hear is the relay itself, there's on for each fixture. The advantage, or so they thought at the time, was that you could switch a light from anywhere, and run a low voltage control circuit to do the switching.

If the wiring and relays are in good condition, there's no inherent danger.What the heck are these old light switches and how do they work?Holy those are old. I have a 100 year old house. but all the wiring is upgraded. You probably have old Knob and Tube wiring..very old and potentially very dangerous.

Because the uses of electricity has changed so much in the past 60 years since it was last installed it is common to find circuits that were extended by home owners who may or may not have done a good job. Because knob and tube was installed without junction boxes people think they can still make connections without junction boxes when in fact this is not any longer allowed. Lastly since the wiring is typically quite old the chances of it having been damaged is higher and it has aged, meaning the sheathing may be brittle or broken.

As far as your's a mater of guess work ...There is no rhyme or reason or standard set in the day. It went with if it works...great. The days of shim it it will be fine.

Don't run the hair dryer and the curling iron at the same time and please stop trying to make it buzz.

Please call the old priest not the young one to look at it (Electrician)What the heck are these old light switches and how do they work?In 25+ years of home remodeling, I think I've seen this once, ever. If you have the same system as the one I saw over 10 years ago, here's my best guess.

This was built and sold as a %26quot;Smart House.%26quot; What little I saw involved a team of electricians tearing out every multi-button light switch in the house to be replaced with conventional light switches. It was an expensive and time consuming venture. And I believe vast numbers of relays were in fact the source of the trouble. Some worked, most had stopped working, and light control became erratic and spotty at best.

At the very least, get an experienced electrician to evaluate the currentt situation. Keep in mind, someone in their late 40s or early 50s would most likely have seen this before.

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