I'm looking at buying some of these smart light switches. They say max 300W per gang, but my bathroom has two heater lamps which combine to 550W.

On a scale of "eh it's well within safety margin" to "you will definitely burn your house down you idiot", how unwise would it be to run that 550W through this switch?

No need to be worried, I'm not planning on doing this unless something 100% convinced me, this is mostly just curiosity about typical safety limits etc. Current plan is to replace with weaker bulbs.

  • I doubt you'll burn your house down. But the switch likely won't last very long. Switching to weaker bulbs is not going to be very satisfactory - unlike light bulbs, where they keep getting more efficient, with heat bulbs you are putting 1 kWh in and deliberately getting 3,412 BTU out. Fewer kWh ==> fewer BTU ==> won't heat up the room as well. Find a switch rated for higher capacity. – manassehkatz-Moving 2 Codidact Apr 29 '20 at 4:55
  • 3
    Too many fires are caused by this type of action. Get switches rated for the total task or change the lamps. – Solar Mike Apr 29 '20 at 5:29
  • That's really complex design and a diversity of products for a company that can't build a competent web site. No, this is a motley collection of Alibaba finds. I also found your company's smoke detector once again identical to an Alibaba staple. So no, it's dirt cheap junk, to answer your safety question. No safety certs that I can see (except for China Export CE , of course). – Harper - Reinstate Monica Apr 29 '20 at 6:12
  • I'd have to say, I'm leaning towards the "Idiot" side. You're considering running this thing at nearly 200% of it's rated power (and, therefore current), on the say-so of the some strangers on the internet. That'll go down well with the insurers, when you're claiming for the fire damage - "but, Stack Exchange said it would be OK". Just don't. – SiHa Apr 29 '20 at 8:21
  • It's hard to say. 550W of heat lamps is much easier to start than 300W of incandesscent. but it's harder to run, there's a probability of overheating the smart switch. – Jasen Apr 29 '20 at 10:41

Part of the switch' rating includes being able to break the current repeatedly. Turning off the lamps will create a spark internal to the switch which create a burst of heat. The more current the bigger the spark. Large sparks can damage the housing or contaminate the contacts, either of which can result in fires should they be let unchecked.

You can instead use a relay rated for the voltage and current (and from a trustworthy source) and have the smart switch control the relay directly which in turn switches the lights.


I checked out the company's product lines. All very handsome products, but with conflicting design language, and they can't seem to run a competent web site. Instead of PDF spec sheets, they have low-resolution images of them. (a sign they didn't pay the artist).

Anyway, I spot-checked some of their products on that spewmonster of Chinese junk, Alibaba.com. Yes indeedy, every one of their slick designs is offered for sale by several companies on Alibaba.

Nothing like that should ever be connected to mains power. It is unsafe junk. It either has no safety stamps, faked safety stamps, or the dreaded CE mark (China Export, but designed to look just like Conformité Européene).

Now I've been known to use that junk for low-voltage low-current projects, like 12V LED lighting. Whatever they claim, you derate that by about 2/3, so a "30W" power supply can be trusted for 10 watts (but not really even). Asking it to perform double-spec is out of the question.

Not the answer you're looking for? Browse other questions tagged or ask your own question.