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I am reviewing a remote-control appliance switch on Amazon. (Edit: this is a plug-in switch. Switch plugs into outlet, appliance plugs into switch.) I find that toggling it off breaks the neutral side but the hot slot on the outlet is always hot. I know it’s unsafe, but how best to explain it in terms a non-electrical-savvy person can get it in just a few words? A realistic scenario where someone could get hurt would be good. It seems otherwise a good product. How many stars should I dock it for this?

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    For some people the only way is for them to test it. With switch neutral, having the switch off and touching hot and ground hurts. With switch hot touching neutral and ground does not hurt. They get the lesson better if they use their tongue. If product only switches neutral off then dock every star as product is dangerous and probably not legally listed for use in North America.
    – crip659
    Nov 9, 2022 at 22:41
  • I think maybe you could edit your question for a better explanation. It seems as if you want an explanation on if it is harmful for the system/circuit. It will not do the circuit any harm or damage and the circuit will work as expected. It can hurt and/or kill people because the fixture is always hot/live with the switch off.
    – crip659
    Nov 10, 2022 at 12:40
  • recommend that folks buying this file down the wide plug prong (if it has one) and install it upside down. That sounds wacky enough most folks will choose another of the 1000+ options in this market.
    – dandavis
    Nov 11, 2022 at 21:38
  • @dandavis it has a grounding plug so I can’t flip it over. I think I will just rewire the receptacle with hot and neutral reversed and advise people to do that. Is that wacky enough?
    – raygard
    Nov 13, 2022 at 15:33

3 Answers 3

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The switch in question is not UL Listed, and has counterfeit CE. Stop right there; that's all you need. See bottom.

How to describe it

When you arrange a switch to interrupt neutral, it means everything past the switch is energized when the switch is off.

The hot wire is energized because you do not disconnect it ever. The disconnected neutral is energized because it is connected to the hot wire via the bulb.

Worse than that, if it's still a fixture with replaceable bulbs, the shell of the light socket is energized too. You might say "it's disconnected when you take the bulb out" but that's only true if there's only one bulb.

There is no way to de-energize the light socket, and no way to remove a broken bulb safely.

This is ever more important, since many LEDs use a cheap capacitive dropper that energizes the heat sink of the LED. That's a problem on a broken LED where the manufacturer has shielded the heat sink as UL and CE require. But if the user is buying cheap Cheese smart switches, they are probably also buying cheap Cheese LED bulbs. Those aren't UL Listed, and their CE is counterfeit. Big Clive has many teardown videos of those having exposed, energized parts from the factory.

So yes, cheap mail-order LEDs + cheap mail-order switches are a recipe for disaster.

How did this happen?

All the first world countries have consumer protection. The apparatus that protects the supply chain from dangerous products only works on items sold at reputable bricks-n-mortar stores. Mail-order does an end-run around that apparatus by forcing the enforcement over to Customs, and they have other priorities, understandably.

Amazon Marketplace is probably the worst for this since these are the same cheap Cheese crud that you find on eBay, yet it has feel of safe reliable Amazon. Plus Prime shipping. Note: On that link, don't go looking for the "skip ad" button, that ad is what I'm trying to show you. It neatly explains why this junk is so insidious.

Thus, the only way to reliably buy equipment is at bricks-and-mortar sellers, or mail order operations run by those bricks-and-mortar operations which only offer items sold in the stores (e.g. wickes.co.uk or lowes.com). Beware of places like Walmart (blending in Amazon items) or Sears (blending in eBay items).

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  • The multi bulb lamp is exactly the example I needed. And I have mine plugged into this switch right now and didn’t think through the implications <embarrassed />. I’ll try to update my review with this example. BTW the video is an eye-opener. If I weren’t retired and lazy, maybe I could be an Amazon marketplace millionaire too.
    – raygard
    Nov 10, 2022 at 15:06
  • There are plenty of trustworthy suppliers who sell mostly or entirely by mail order and there are plenty of physical shops who buy stuff from questionable sources and resell it. Amazon's blurring of the line between retailer and marketplace site is definitely a problem though. Jul 21, 2023 at 20:04
  • @PeterGreen Wrong, and the reason is, enforcement is civil, and relies on the person having assets within reach of enforcement. Bricks and mortar shops can't afford to be caught with a store full of dangerous trash because the government can walk right in and catch them. Whereas the Amazon Marketplace model is specifically designed to thwart interception by Customs (free trade zone) and to shift liability to untouchable actors. Yes, what you say is possible, but it isn't what happens at scale. Jul 21, 2023 at 21:22
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The problem is that the hot line is still energized inside the appliance so if anything goes wrong with a bad connection or broken wire, the appliance, let's say a toaster can become energized and touching it while turning on the kitchen faucet could be deadly because the faucet could be grounded.

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  • thanks but I’m aware of the dangers in that scenario. This is a remote-controlled plug-in switch, not in-wall. The switch plugs into the outlet, the appliance or lamp plugs into the switch. I know it’s dangerous but what’s a realistic scenario for trouble? Not likely someone is servicing the appliance or rewiring the lamp with it plugged in.
    – raygard
    Nov 9, 2022 at 22:55
  • @raygard edited answer. does this help?
    – JACK
    Nov 9, 2022 at 23:10
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    @raygard You don't check the Darwin Awards that much do you?
    – crip659
    Nov 9, 2022 at 23:18
  • Yes @JACK that’s a better answer, though if the toaster has e.g. a hot chassis, it will be deadly when it’s supposed to be on anyway. (And most toasters are plugged into always-on outlets, and they’re supposed to have GFCI protection on a kitchen counter…).
    – raygard
    Nov 9, 2022 at 23:58
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    @raygard GFCIs in kitchens is a recent(20 to 30 years) thing. Quite a few older homes do not have them installed yet.
    – crip659
    Nov 10, 2022 at 0:06
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The classic example for problems with "switched neutral" or "hot/neutral reversed" is the traditional Edison light bulb socket. Neutral is connected to the outer part and hot to the button in the very tip of the bulb. If everything is done correctly, this means that:

  • If the switch is off, the socket is 100% "dead" and safe to touch.
  • If the switch is on and you change the light bulb, it would be hard (though not impossible) to touch the hot part of the circuit.

If neutral is switched but not hot then even if the switch is off there is hot lurking inside the socket - touch it when grounded and zap.

If hot and neutral are reversed then not only do you have the "switched neutral" problem, but you also have a situation where changing a light bulb would get your fingers awfully close to the hot.

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