Comment by xenadu02
17 hours ago
US style plugs and derivatives (and Australian, Japanese, Brazilian, etc) - all invented by Hubbell - are "good enough".
Are they objectively good? No. Do they regularly fail, cause fires, or shock people? No.
Even my kids when young understood how to grip the plug without touching the metal contacts and to this day still have not been shocked. In theory can something fall and hit the pins just right to cause a short? Sure. You could also get struck by lightning. In practice it just doesn't happen very often.
For the US/North American NEMA style there are some improvements and some clever things about them. Modern receptacles have shutter doors that stop you from putting anything into the holes unless the ground pin or neutral pin unlocks it first. Many plugs also cover the rear part of the hot/neutral with plastic so if the plug is not fully inserted there is no exposed metal.
The plugs also prevent mixing voltage and amperage. The typical two vertical blades (5-15) are for 15 amp circuits. 20 amp circuits (5-20) have one horizontal + one vertical blade. The receptacle has a T shaped slot to match - that way you can plug a low-amp device into a high-amp circuit but not the reverse.
Similarly the 240v version of this plug (6-15/6-20) has the same property: 15amp and 20amp versions. The 15 amp is two horizontal blades. The 20 amp is one horizontal + 1 vertical but swapped places compared to the 120v version. I do wish more builders installed the 240v receptacles in kitchens in the US. There is no technical reason we can't have higher power kettles and whatnot. If code required these in garages and kitchens more appliances would be available for them.
(I find it insane that Brazil continues to be dual exclusive voltage; all of North America is dual concurrent voltage. Every home/office has 120v and 240v available. In Brazil it depends on what state/city you live in - some get 120v, some get 240v. Even worse they use the same standard plug design for both so you'd better hope the plug is the right color or has the right sticker. And you can't be sure you can take electrical appliances from one city to the next! At least they should have adopted different plugs for different voltages.)
The huge advantage of these plugs is compatibility. We already have them. The cost to change designs is massive. The benefit extremely small. It just isn't worth doing.
Note: The 240v NEMA plugs I am referencing are not "dryer plugs" which are physically much* larger and designed for much higher amp loads in the 30-60 range. The 6-15/6-20 are literally identical to the standard 120v plugs but with different blade orientations. They were designed to support 240v appliances in everyday use since all of North America is dual voltage. In practice 240v is only ever used for large appliances like ovens so the 6 series doesn't get much use which is a bit of a shame.
> US style plugs and derivatives (and Australian, Japanese, Brazilian, etc)
Brazil no longer uses US style plugs (though you'll still find them in older installations), it nowadays uses a much safer EU-derived style.
> I find it insane that Brazil continues to be dual exclusive voltage; all of North America is dual concurrent voltage. Every home/office has 120v and 240v available. In Brazil it depends on what state/city you live in - some get 120v, some get 240v.
This is wrong; it's very common to have for instance both 127V and 220V in the same building, sometimes even side by side in the same wall faceplate; 127V is phase to neutral, 220V is phase to phase (on the common 3-phase system). Yes, it does depend on the city, some cities use 220V exclusively, and there are a few other variations, but AFAIK the 127V/220V 3-phase combo is the most common.
> Even worse they use the same standard plug design for both so you'd better hope the plug is the right color or has the right sticker. And you can't be sure you can take electrical appliances from one city to the next! At least they should have adopted different plugs for different voltages.
Yeah, at least it's better than the confusing mix of legacy sockets we had before (which already were mixed voltage - and yeah, we already used the "120V 5-15 NEMA plug" aka "computer plug" even for 220V).
> The plugs also prevent mixing voltage and amperage. The typical two vertical blades (5-15) are for 15 amp circuits. 20 amp circuits (5-20) have one horizontal + one vertical blade. The receptacle has a T shaped slot to match - that way you can plug a low-amp device into a high-amp circuit but not the reverse.
Alternatively you can just run everything at 230V and then you don't need a million different plugs as any wall socket can provide up to 3.5 kW, enough for any home appliance except for the most power hungry ovens and IH stoves.
Rewiring an entire country is a wee bit expensive. Even if the wires are rated to 300V (they usually are), transformers would have to be replaced, and they cost quite a bit. Also different sockets and circuit breakers, and a whole lot of billable hours by licensed electricians.
(But changing the voltage is easy compared to changing the mains frequency. Japan still has to live with 50Hz in one half of the country, and 60Hz in the other.)
The transformers are fine as they are. We already have 240VAC in the typical US home: Two legs of 120v, with one being 180° out of phase. That part exists and it works fine -- the big industrious parts of the infrastructure are already supplying 240v.
US 240v is a bit different than the way the rest of the world usually does it, where they have 1 leg of 240v and 1 neutral, but AFAICT that detail is not a big deal for the stuff that actually uses electricity.
The wire itself, broadly-speaking, is fine.
Suppose we decided that tomorrow at noon to begin the move to 240v.
We just refactor our breaker panels and update to some new objectively-good whiz-bang outlet format (because we would certainly never borrow existing designs from anywhere else on the planet; we in the States have a big problem with Not Invented Here when it comes to policy), and finally get rid of twist-in Edison light bulb sockets, and that part is done.
But then all kinds of stuff doesn't work anymore.
Fridges, garage door openers, microwaves, light bulbs, clock radios, natural gas furnaces, and anything else that doesn't work with 240v: That stuff is dead in the water without converting back down to 120v using an autoformer or something.
Sure, we'll eventually get things updated; when we don't count survivorship bias examples, it's plain to see that stuff just doesn't last all that long anyway (and never actually did).
But for a time: There literal mountains of stuff that just won't work without help. And that's a tough pill to swallow.
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What we could start doing is embrace our existing dual-voltage home wiring methods, and putting 240v sockets in some places where it's actually beneficial. Places like kitchens (for heating water and food), say. But broadly speaking: Nobody does this because nobody sells safety-approved residential appliances for the US domestic market, so it's a lot of money to spend to get it done for no benefit. It's a catch-22.
> The plugs also prevent mixing voltage and amperage.
There are Chinese suicide receptacles with T-slots on both sides allowing you to intermix all NEMA-5 and NEMA-6 variants.