US 220V 20A TO CHINA 220V 10A MAHJONG MACHINE

[gfretwell]

Transformer power supplies are not that forgiving unless you have taps on the input. Even then. they run hotter on 50hz unless they were wound for it.

[James Wilkinson Sword]

My house is a lot simpler. 240V and 0V. All the 240V lines have a FUSE on them, none of this namby pamby circuit breaker shit causing false positives. I don't have to worry about crossing between circuits, there's only one 0V line, and it's the same as "earth". Both are wired together at the meter, then go back as the shielding on the armoured cable from the utility transformer. I often use earth instead of neutral, because having no circuit breakers, it's doesn't matter!

[gfretwell]

I think it is just a clever way to wind the current canceling transformer in the GFCI

[James Wilkinson Sword]

I never had a problem with non-switching supplies which just used a transformer. They were rated as wide as 200-260V. There was regulation (crudely - as in throwing away excess voltage as heat) before switching.

[Jeff Wisnia]

Ralph you just reminded me that about 63 years ago when I was a student living in a dorm room at MIT. I acquired a 240 volt window air conditioner and wanted to use it to cool our toom. It turned out the wall outlets in the room next to ours were on the other side of the 240 volt line so we ran a single wire out our window and into the window in the next room. Presto, problem solved.

The next year I moved out of the dorm and rented an apartment across the Charles river in Boston. Shortly after I hauled my stuff over there guess what? I found out that building was one of many there still on DC power and none of my beloved stereo equipment would work. I managed to talk my way out of the lease because of that and found another place that had already moved to AC power.

Lots of other funny things happened back then, like I went to try phone sex but found out the holes in the dial were too small.

Jeff

[James Wilkinson Sword]

Who knows, safety really doesn't interest me. To me, you install a fuse to prevent overload and fire, who cares about anything else?

[James Wilkinson Sword]

Direct current? Oh my god how old are you?!

[Ralph Mowery]

My dad was born in 1920 and for a good number of years serviced home appliances. He always said 110 and 220 volts. I picked that up and often use 110, 220 and when talking 3 phase like I often worked on will often say 440 instead of 480.

Lots of things from the 1950s or so was listed at 115 volts. The voltage does seem to be creaping up in the US. I have one of the inexpensive meters that stays plugged into a socket that usually is 123 volts. It seldom goes over that, but will sometimes show as low as 118 during times the line heavy loaded. I did calibrate that meter to a Fluke that the calibration was checked by a certified calibration company, so it should only be off the + or - of one digit.

High quality tube equipment may have taps for the line voltage as the filiment voltage is critical to how long they will last if it goes over

5 % high.

[Mark Lloyd]

[snip]

These might have been what we had in the apartment I when in during 2nd grade. I just remember my father saying you can use only half of each plug. These apartments belonged to the university, and there were a lot of foreign students. Maybe that explains the 240V receptacles.

Would each half be on a different circuit?

[Sparky]

Why didn't you simpletons just go with 480v?  Think of all the money you'd save on copper wire.

[trader_4]

A 240v gfci breaker with neutral provides ground fault protection just like any other gfci. It sums the current in all 3 conductors. You can have both 120v and 240v loads.

[Jeff Wisnia]

Nine squared plus one as of February 10th.

Jeff

[gfretwell]

I suppose we could go dig up Thomas Edison and ask him why he wanted to use 110v but we seem to be stuck with it now. It could have been worse. Old Tom wanted 110v DC.

[gfretwell]

Yeah but when your RCD trips, the whole house goes dark. Then you are on an easter egg hunt looking for the cause.

[gfretwell]

It is all one circuit with one of the 240 legs going to the 5-20 receptacle along with the neutral You bring 2 ungrounded conductors a neutral and a ground to that box normally. You could even make it more interesting and put that in a 4" box with another 5-20 or 5-15 duplex on the other ungrounded leg.

[Bob]

I suspect you'll prolly have to give jws another hint.

[trader_4]

se namby pamby circuit breakers, you just had -110V, 0V, +110V. You could take 110V from either of the 0V and 110V wires, or 220V from the two 110V w ires. Do the circuit breakers think there's an earth fault if you try to r un a 220V device off two 110V wires?

linked and run off a dual breaker which would accept a 220V device?

240v and through 0V, and if they differ, some must have escaped to ground a nd it cuts the power.

tween -110V and +110V, or from one of the 110V wires to 0V? You'd have to have a very clever mechanism that monitored THREE currents and compared the m all somehow.

Why do you think it's so hard to measure current in 3 wires, versus 2? It' s not.

[trader_4]

On Thursday, February 15, 2018 at 4:17:54 PM UTC-5, James Wilkinson Sword w rote:

e:

those namby pamby circuit breakers, you just had -110V, 0V, +110V. You cou ld take 110V from either of the 0V and 110V wires, or 220V from the two 110 V wires. Do the circuit breakers think there's an earth fault if you try t o run a 220V device off two 110V wires?

ere linked and run off a dual breaker which would accept a 220V device?

gh 240v and through 0V, and if they differ, some must have escaped to groun d and it cuts the power.

between -110V and +110V, or from one of the 110V wires to 0V? You'd have to have a very clever mechanism that monitored THREE currents and compared them all somehow.

about a twin 120v GFCI breaker. Would it care if some current didn't go t hrough neutral? I guess it can't, as two equal 120v loads would mean it ne ver went into neutral at all.

're electronic, I can't begin to imagine how else that would work.

All gfci breakers or receptacles are electronic.

[Jeff Wisnia]

Go to this page:

Where you will find this:

Remnant and existent DC systems

Some cities continued to use DC well into the 20th century. For example, central Helsinki had a DC network until the late 1940s, and Stockholm lost its dwindling DC network as late as the 1970s. A mercury-arc valve rectifier station could convert AC to DC where networks were still used. Parts of Boston, Massachusetts along Beacon Street and Commonwealth Avenue still used 110 volts DC in the 1960s, causing the destruction of many small appliances (typically hair dryers and phonographs) used by Boston University students, who ignored warnings about the electricity supply.

See?

Jeff

[James Wilkinson Sword]

I've got several multi-adapters - they've got a UK plug on one side, then weird shaped holes on the other side that you can fit anything into.