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HOWEVER: these are NOT 180 degrees out of phase. It is more like 120 degrees. I am taking it that America also has 3 phase supplies, rather than 2.

I liked your article. It had a lot of good pointers for others. It may be a good idea to add a red indicator between neutral and ground for the two incoming 120v lines. That way, if the hot and neutral are reversed, the light will come on.

I suppose the other point of note is that compared to 220/230/240 Euro voltages, residential 240 is not 240 to ground. The only things that have such high voltages to ground are either corner-grounded 240 deltas (which are exceedingly rare) and 480/277Y systems (which admittedly I do a lot of work with). I also really like how in the US we have such an extensive system of completely non-interchangeable, unique connectors for all the different voltage and phase combinations that one might find (thanks, Harvey Hubbell!)

After a long, bitter, loud argument with the plant “electrician” I finally got him to check the distribution board, when we opened up the “big grey box” first thing I saw was all the earths, bundled together with tape and just hanging there. From where I was standing I saw a fuel tanker driver hooking the earth lead to his truck, which came into the same box.

When potential EV adopters ask me how long it takes to charge my i3 I don’t have to say “ugh… like 22 hours for a full charge…” Instead I get a much different reaction by saying: “after a normal day of use I plug in my cell phone and my car at the same time and usually the car gets to 100% first… but DC fast charging stations can go substantially faster”

I understand it’s only about 20hz, which is why it gives you that interesting jiggly feeling instead of a good Wack like mains power at 50/60 Hz does. When I was still a young buck in my early 20’s I worked in a mid-sized company and one of my duties was to maintain our POTS lines; my boss who might have been a sadist would often have me remap the phone lines mid day while the lines were in use and insist that I was not to busy any lines out. I can only amagine my coworkers delight at the inventive array of profanity that would come out of the wire closet when the reception switchboard would light up during these sessions. Sti got my lines man’s handset stashed somewhere…lol

After checking to make sure the outlets are wired correctly, a 220v light bulb with light up across the two hots if they are opposite phase and not if they are the same phase.

Alternatively, the stillborn 42V automotive power standard is another solution. http://en.wikipedia.org/wiki/42-volt_electrical_system

Yes, agreed, actual power supply design must take into account the allowable possible range of input. My house nominal “240V” supply routinely hits 252V, for example, and is allowed to go as high as +6% (254V).

I don’t approve of that design. It lacks the third relay, which means that if you plug into two circuits on the same phase, you get 0 volts between the two hots, but both are still 120 volts away from ground. That means that the equipment doesn’t work, but it’s not safe to poke at. I prefer to insure that the 240 volt outlet is guaranteed to either be completely dead, or properly powered.

Of course in this case, there’s less heat per length of track, but the tracks are longer. So it cancels itself out in the end.

The outlet on your wall is likely on a 15 amp circuit, so in many cases, the Smart Plug can handle as much power as the breaker or fuse can. To see what the power requirements of many electrical devices are and what type of load they create, you should visit Electrical Safety First. It’s a site based out of the UK, but the power ratings for products are the same no matter which country you use them in and the charts here are an invaluable tool.