View Full Version : A question for those living in 120v/240v countries

August 9th, 2019, 04:06 AM
for those of you living in counties with the the 3-wire dual voltage system that has 120 volts and 240 volts (or 208 volts when tapped off 3-phase or 127v/220v in Mexico) ... who connects their 100-240 volt capable computer power supplies to 240 volts?


computer continues to run when there is a serious brownout (some can go to half voltage).
voltage is balanced so there is no 60 volt phantom voltage that can mess with digital voltage meter readings.
some power supplies are more efficient at higher voltage up to their max.
lower current on building wiring means more efficiency (why the power company uses 12000 volts and higher).


requires wiring in a new circuit if one was not already there.
uses 2 slots in the breaker panel instead of the usual 1.
may not be allowed in some places (may not pass inspection if one was done).
UPSes are more expensive (need commercial/industrial grade versions).
fewer power strip and surge protection options (but some do exist).

August 9th, 2019, 06:50 AM
which countries are that?

we have 220 V but the oven is hooked up on 3 wires.

August 9th, 2019, 07:34 AM
i know for sure that USA and Canada have the "Edison style" 3-wire split voltage system that was originally 110/220 volts when he ran his service with DC. AC used the same voltage and system. the official voltage was increased to 115/230 during world war 2. sometime shortly after the war it went up to 120/240. you may have 120/240 even if people still call it 110/220. but in Mexico they are doing things a bit different. they set up 3-phase transformer sets with each phase at 127 volts. between phases that get about 220 volts (sqrt(3)*127) instead of doubling the 127 to 254. these voltages are close enough that it works with most things, though incandescent light bulbs do run a bit bright and a bit shorter life. i think Belize and Central America have the same system as Mexico.

where are you located? do any of your "220" plugs have 4 prongs? do you have a voltmeter to measure the exact voltage with?