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I have a circa 1920 push-button light switch which sticks occasionally. The push buttons move fine, but sometimes the blade switch inside doesn't flip unless the button is pressed very hard. I'd hate to replace this, because this antique switch has a more solid feel than replicas I've used. Is there a safe lubricant for mains power the switches?

And yes, I plan to remove the paint. :)

3-way push-button switch

Edit: I would take it apart to clean, but the screws have been sealed by some kind of resin.

3-way push-button switch back

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    It has a solid feel because it’s rated to interrupt DC. That means it snaps the contacts far apart very abruptly to snuff the DC arc. Since DC never goes to 0 volts, a DC arc is hard to stop. **So it’s necessary the “off” have a different action and feel than the “on”. To see something else like that, look at a modern circuit breaker.
    – Harper - Reinstate Monica
    Commented Jul 3, 2020 at 6:44
  • @Harper-ReinstateMonica, very cool tidbit about DC. Were these still being made with Edison vs Telsa designs? This being a 3-way switch, I suppose both directions needed to be very snappy.
    – zwiebelspaetzle
    Commented Jul 3, 2020 at 14:40
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    Possibly mineral oil, as it's non-conductive (it's what electric pole transformers are filled to the top with), and di-electric grease may be another option.
    – JW0914
    Commented Jul 4, 2020 at 20:33

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Oil, no. Lubricate, yes. Common oils have multiple problems for electrical devices, the worst of which is possible flammability. You can get specific electrical "contact lubricant" for this though. It is usually not sold in hardware stores, you may have to order it on-line and the smallest package will be a lot more than you need, but don't substitute. And to those who will tell you "WD-40", that is NOT a good lubricant, despite what people think. It's main purpose is as a water displacement agent, in fact that's what the "WD" stands for (Water Displacer, attempt #40 is where the name came from). As a lube, it only lasts a couple of weeks before it breaks down and evaporates.

And NEVER apply any lubricant to an energized device.

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I would use dielectric grease, which is widely available at auto parts stores. Apply to blades, contact points and pivot points with a toothpick, bamboo skewer or other applicator. Work the mechanism a few times and apply a little more. Power off, of course.

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    dielectric grease is an insulator, so wouldn't applying it to contacts prevent a proper connection/the flow of electricity?
    – Yorik
    Commented Jul 3, 2020 at 20:02
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    @Yorik Yes, dielectric grease is an insulator but at the microscopic level it promotes a smooth sliding metal-to-metal contact between switch parts, and that contact is conductive. Manufacturers use it in switches and other equipment. Next time you're in Home Depot, find the Square D circuit breakers and look at the contacts on the back of the breakers. You'll see a blob of dielectric grease.
    – MTA
    Commented Jul 4, 2020 at 2:00
  • @MTA - that grease may well provide some lubrication to assist sliding - but do contacts slide against each other? I thought they snapped together and apart.
    – Tim
    Commented Jul 5, 2020 at 9:14
  • @tim The "snap" always includes some sliding. Google "contact wiping action" for more info.
    – MTA
    Commented Jul 5, 2020 at 14:30
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I would spray it with contact cleaner. And then cycle the switch several times.

That should clean out any gunk interfering with the operation.

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Use switch cleaner spray to clean any gunk away, then use a silicon grease with a small craft paint brush.

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    Hello, and welcome to Home Improvement. Thanks for the answer; keep 'em coming. And, you should probably take our tour so you'll know the details of contributing here.
    – Daniel Griscom
    Commented Jul 4, 2020 at 16:41
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I wouldn't.

Most oils are flammable.

Those that are not are usually toxic.

Substances that are used to improve contacts don't generally deal with interrupting contacts. Expect soot buildup.

Any (organic) liquid may degrade the primitive plastic of the buttons.

And finally, you have a better course of action: Disassemble it and see where the moving parts have worn out. Some of these can be assembled with some part flipped and work 50 more years.

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  • Thanks for the tip about disassembling it. I'd do that, but the screws holding it together are covered by some kind of resin. I'm not so sure I could chip that off without breaking the ceramic housing. :(
    – zwiebelspaetzle
    Commented Jul 3, 2020 at 14:43
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    @zwiebelspaetzle Instead of disassembling it, remove and dunk in an ultrasonic cleaner for 10 minutes. No disassembly required, though you would want to actuate/operate the switch a couple times in the cleaner. Dry thoroughly too
    – Criggie
    Commented Jul 3, 2020 at 19:08
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That material that's covering the screws can be removed by putting a drop of acetone on it and letting it sit for a few minutes. Then simply unscrew whatever you're trying to take off.

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There is a type of dry lubricant that is easily accessible and can lubricate your switch.

A pencil (aka Graphite).

You generously write over the area where you need lubricated, use the switch a few times, and keep doing it until it starts working again. The graphite works great as a lubricate and doesn't "leak" everywhere.

Graphite does conduct electricity, but you have to pack the switch with graphite powder before this is an issue.

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    Is this safe, or just safe enough?
    – Criticizing Israel not allowed
    Commented Jul 3, 2020 at 18:08
  • just almost safe.
    – fraxinus
    Commented Jul 3, 2020 at 19:10
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    I would recommend avoiding graphite anywhere near an electrical switch. There's way too high a chance that it will migrate into the contacts and cause shorts.
    – CCTO
    Commented Jul 3, 2020 at 19:49
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    I support cooment of @CCTO. Graphite conducts electricity which is a good thing when it is restricted to parts intended to be electrically connected, but can connect other parts. I disagree with Nelson that "you have to pack the switch with graphite powder before this is an issue"; it can take only a few grains to make an unwanted connection.
    – user20637
    Commented Jul 3, 2020 at 21:50

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