Switches on appliances with unpolarized plugs

[moderneezer]

Hi, it's Moderneezer.

There's something that has gotten into my mind lately which relates to electric wiring. It's about switches on appliances with unpolarized plugs. Inform yourselves about the difference between polarized and unpolarized plugs, and also about the different plug shapes in the different countries on earth.

If an appliance has a polarized plug, then its switch would only need to cut the hot connection (also called active in Australia), but with an unpolarized plug, the appliance should have a switch that cuts both the hot and the neutral connections when turning off the machine. It said said, however, that appliances with unpolarized plugs used in the countries of mainland Europe generally have single-pole switches.

It is said in some websites (they're in French) that an appliance, with a single-pole switch, would generate some form of radiation if the hot connector is connected to neutral and vice-versa. American electricians are worried about other kinds of problems if a machine is plugged with reversed wiring.

The pictures are the wiring diagrams of canister vacuum cleaners. The canister represented in the first picture has a single-pole switch and is assumed to have an American plug with the neutral blade being wider than the hot blade. In the second picture, the appliance has a double-pole switch and is assumed to have an unpolarized European plug with cylindrical prongs. The machine in the third picture is assumed to have the same kind of plug as in the second diagram but with a single-pole switch. Notice the exclamation marks to warn us about some dangers?

So, in conclusion, an appliance with an unpolarized plug should have a double-pole switch but most of the ones in mainland Europe don't. What do you think of my opinion?

 

[n0oxy]

polarized plugs

I've wondered what the point is of having polarized plugs in the first place. If it was direct current, it would matter since direct current can have a center positive or center negative connection. But with alternating current, it shouldn't matter. I actually have a few older vacuums that have non-polarized plugs, it works fine either way you plug it in.
Mike

 

[madman]

There's no radiation - not even EMF - when the thing is off, unless it has some circuit board that is always powered on, and even then, there's only so much radio waves a tiny little circuit board can create. That's a non-issue either which way.

You're overlooking the actual problem with non-polarized appliances entirely.

In the US and Canada, we use 240 volts. Yes, you heard me. It's split into two 'phases,' each being a 'Hot.' Hot and Common are the somewhat antiquated North American terms, while Line and Neutral are European terms. With the two phases, the Neutral is in between the two (hence the name). Neutral is also connected to Ground. So in many cases it can be treated as Ground, but that subject is complicated.

Now consider why the Line (Hot) is preferred to be the switched wire. If everything is ok, it really does not matter at all which wire is switched. But like so much in electrical code, it's all laid out for when something is NOT ok. Take for example a vacuum cleaner, a canister with a power nozzle. It's plugged in, switched off, and it has a fault. A wire is exposed, not in the cord, but somewhere after the switch. Perhaps on the power nozzle cord. It doesn't matter which wire, because even with the switch off, the whole electrical circuit is still technically live, since it's a single pole switch, one wire is still connected to the circuit of the machine, only the circuit is not complete. That means the whole thing is live referenced to Neutral - because the plug is polarized, and the switch is (correctly) on the Line side. If for example, you touched the exposed wire, you would then be live referenced to Neutral. The easiest way for you to complete the circuit would be to also touch something grounded. A screw on a light switch plate or a plumbing fixture, for example.

Ah, but remember Neutral is Ground (for our purposes). So you wouldn't get shocked. Imagine if the plug was wired wrong, or the switch interrupted the Neutral side instead, or the plug was non-polarized and you lost the 50/50 chance of plugging it in correctly. Well, then you'd be referenced to the Line side, and you'd get 120 volts across you to Ground. Because Ground is Neutral.

That's the whole reason plugs are polarized. You will note that it is an extremely specific example. Because for the polarization of the plug to matter much, it really needs to be a very specific situation. In other words, polarization should be observed, but it really isn't that big of a deal if it's not. It's really just a matter of 'just in case.' It's like keeping a fire extinguisher. You're never gonna need it. Until you need it.

But, as I understand it, on the other side of the planet, homes do not get two phases. They just get 240v or 220v on a single Line and Neutral. And I don't really know if neutral is grounded. I think polarizing mattered in North America a bit more in the old days when it was more common to have metal appliances, especially radios and TVs with metal chassis that were actually live all the time normally. Then, the potential for touching a live chassis and also touching something else live meant there was a possibility that you would not just get the one phase (120v), but go from one phase to another (240v). In fact, I *think* the whole reason polarized plugs were introduced in America was because of radios and TVs.

Also, in America anyway, the only new appliances you'll find that are non-polarized will be double insulated things. Basically that stuff is usually made of plastic, and highly highly unlikely that there would ever be an exposed wire to touch. Like phone chargers.

And in Europe, you're getting 240v shocks no matter what. Funny that England knows that's bad, and so construction sites use transformers to take their power down to 110v, and even that's two phases of like 50v. So you can buy 110v power tools in the UK lol. Matter of fact, I'll bet you could buy a shop vac for 110v.

While we're on the topic, the European round pin plugs (schuko?) suck. In America, our antiquated plug design has evolved gracefully. They really just don't seem to know what to do with theirs. Add to that you have like 20 different countries all trying to make their own plug designs, yet still trying to keep backwards compatibility, and then inter-country compatibility. At least the UK decided to just do their own thing, and as ugly and bulky their plugs are, they at least do their job excellently. Gotta give them that.

Then you got Japan that uses American plugs... though I doubt they are polarized, and I think grounded plugs aren't really a thing there. Also they use 100v, and haven't decided on 50 or 60Hz.

 

[Deleted member 5000]

What's wrong with Schuko plugs?
I never ever had any problems with them (except on the sockets).

The recessed design of the socket means when using round plugs you have to insert the plug quite deep before it makes electrical contact so that means getting a electrical shock from touching the pins is quite a challenge. As for flat "euro plugs" they have isolating sleeves on the pins.

All of these plugs (except pic no4) are not polarized this adds to versatility alongside the wide diversity of different shapes & sizes of Schuko plugs this means they are very versatile.

For applications where polarization is critical Schuko plugs should probably not be used either in that case IEC60309 plugs exist (see pic no4).

They don't hurt when you step on them too.

As for sockets they have shutters that only open when both pins are inserted you can't open them with only 1 pin.

The only problem i can see is with the sockets the ground contact can bend or snap off on old or low quality sockets.

Pics sourced from plugsocketmuseum.nl

 

[madman]

Neat. I still don't like them. Too many different variations. Pins feel like they don't have a good mechanical grip in the socket. Plugs always feel like they're going to fall out. I'm clearly not the only person to feel this way, because those deep shucko sockets exist. Which, actually those seem like a good improvement.

I dunno, maybe it's just preference. What little experience I've had with schucko plugs has been disappointing. That, and your 50Hz PAL tv standard. It's painful to watch. At least modern tv's have fixed that, though.

 

[Deleted member 5000]

@madman

I think at the end of the day everyone's favorite plug is the one they use the most.

Regarding the strength of the electrical contact check out the provided link

 

[madman]

Like I said, the deep socket seemed like a good improvement.

 

[moderneezer]

In case you don't know, I'm trying to tell you that an appliance with an unpolarized plug, (which can be inserted in 2 different orientations in the socket and which is often the case in the countries of mainland Europe) should be designed with a double-pole switch that would cut the flows of both hot and neutral contacts, when turning off the machine, instead of just the hot one, to improve safety when when the hot prong is connected to the neutral hole and vice-versa.

 

[madman]

I mean... I guess. Aren't you in Canada? >_>

I was trying to explain the nuance of why, exactly, that even needs to be considered. It would only really be a very incredibly minuscule issue and that's only assuming that their Neutral is tied to ground like ours (which I don't know). And that's further assuming that it's some kind of appliance that is not double insulated. A lot of the reason it even mattered was (like I was trying to explain) because of metal body appliances and old fashioned hot chassis TVs and radios, neither of which are in common use anymore.

It's funny how America gets crap for our outlets / plugs, when it's really theirs that have problems. Case in point: non polarized plugs.

If their electrical... code... organization... people thought that appliances needed double pole switches, they would have mandated it. Have they?

 

[moderneezer]

MadMan,

Yes I'm in Canada and you have your own opinion about the electrical subjects, that's fine.

About the "crap" plugs that we use in USA and Canada, I came across some articles where it's said that our electric system is primitive compared to the ones across Europe, but off course, I doubt that the changeover of plug shapes across USA and Canada will be easy.

 

[madman]

It's completely unnecessary. There's nothing wrong with our plugs. Changing plugs would be the same as converting to metric, it would cost hundreds of billions of dollars, cause a lot of problems, and ultimately accomplish nothing of value.

Shucko plugs have problems too, but they've been gradually improved, same as our plugs. That seems a much better solution to a 'problem' that's barely a minor inconvenience to begin with.

 

[n0oxy]

comparing electric systems

I think each system has advantages and disadvantages. When it comes to voltage, the rest of the world uses 240 volts and this is more efficient because it requires less current than 120 volts does. On the other hand, many other places use 50 HZ instead of 60 HZ and apparently motors require more windings to work at 50 HZ.
Mike

 

[madman]

Indeed, induction motors, light ballasts, and transformers - including all of the transformers in the power grid, need more windings. Meaning more copper is used, more expense, and they are heavier for 50Hz.

I guess this is offset in North America, those things can be a bit smaller, lighter, and cheaper, but then our user-level wiring (in your house, not on the poles) have to be twice as thick copper.

 

[fan-of-fans]

One thing I've noticed, especially with collecting fans. The older molded on plugs that came out in the 1950s and 60s were very thin and rather hard to grip compared to the newer plugs. They also didn't have any sort of divider from the prongs like newer plugs do.

Also the zip cord that used to come on fans and other appliances back then was much thinner than the stuff they use now. Today's zip cords have much thicker insulation than they did before the 1980s or so. My GE fans from the 50s-70s mostly have their original plugs and cords. I have an electric GE alarm clock and its cord is even thinner than on fans.

Also those dome shaped plugs that were used very early on (probably 1940s and earlier) were very hard to unplug from the wall. There's practically nothing to grip. I do like the looks of them, especially the ornate ones. They look nice on antique fans with the appropriate braided cloth wire. I have a 40s Emerson that has I think the original plug on it.

But in general I try to keep the original cords and plugs on all my fans if at all possible. Some of them I find have replacement plugs put on them, but a lot still have the original ones and I won't change them unless they are cracked/frayed or otherwise a hazard.

 

[fan-of-fans]

Wanted to add

I think few if any American small appliances had polarized plugs prior to the 1980s. Maybe electronics and other more sensitive items did. Although I think polarized wall outlets were around in at least the 1950s, so SOMETHING must have had those plugs back then.

Grounded wall outlets were mostly common througout homes by the early/mid 1960s here. I think they started showing up in wet areas like kitchens, bathrooms, and outdoors in the late 1950s. So some homes had grounded outlets in those areas only at first.

 

[madman]

Yes one of the problems with American plugs was simply the plug designs. Those tiny, skinny fan plugs like you say, had the problem that you could very easily roll your finger and thumb over while pulling them out and touch both prongs. (Which, incidentally, would only piss you off.) You'll notice on modern molded plugs on appliance cords, that there is a high ridge to stop that from happening. A simple improvement.

If I'm not mistaken, TVs were required to have polarized plugs in the 70s, maybe earlier. As I said, TVs and radios were most of the reason polarization was important to begin with. The idea of polarizing had to be much, much earlier, though. I still have some original outlets from a 1927 apartment I had lived in when I was little, and they are polarized. Not grounded, but still polarized. To be fair, even back then, Chicago had very stringent building codes. In the 20s, houses here had to have metallic conduit for the wiring. Still need it. Which is good, imo, romex sucks. In the 20s, it probably would've still been knob and tube wiring, in other locations.

My grandpa's house built in the late 60s, was wired with that old ungrounded romex. Not one outlet in the house had ground. Apparently, it was (and even is still) up to code to simply have non-grounded outlets, and if they were not themselves grounded (like the box they are in is not grounded), you had to use plastic wall plates, with plastic screws. Which they had. But, as I mentioned none of the outlets had ground. That included the 'grounded' outlets in the kitchen for the refrigerator, washing machine, and wall oven. Original 'grounded' outlets, but there was no ground connection at all. Unscrupulous builders, I say. Cookie cutter subdivision houses. We wondered why the roof decking was sagging, and then I discovered that it was 3/8" thick plywood on 24" centers.