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I have a eTopxizu 12v 30a DC Universal Regulated Switching Power Supply. The power inputs are marked Ground-Neutral-Load. It has a switch on the side that adjusts it from 110 volts to 220. When I adjust it to 220 volts does this change the inputs to the USA standard for 220 volt where it is Ground-Hot1-Hot2 OR does it still require a neutral with a 220 load on the single L input? The reason is I would like to use this power supply to convert a USA 220 three prong output to 12 volts.

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  • \$\begingroup\$ It more likely changes some of the internal circuitry (i.e. the rectifier - from voltage doubler to full bridge) rather than changing the pinouts, I doubt the pin order would change. \$\endgroup\$
    – Sam
    Jun 9, 2016 at 6:04

2 Answers 2

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When I adjust it to 220 volts does this change the inputs to the USA standard for 220 volt where it is Ground-Hot1-Hot2

It will almost certainly be fine to connect one of your hots to the "L" terminal and one to the "N" terminal and set the switch to 220V. What matters is the voltage between the "L" and "N" terminals not where that voltage happens to be in relation to earth.

Note that a 120/240 switch is a sign of an older power supply design that will almost certainly be inefficient and have poor power factor.

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  • \$\begingroup\$ The unit is a brand new Ham radio power supply. All I need from it is approximately 6 amps at 12 volts. The important thing is the line in is a 3 cable American 240 volt, 30 amp line. If I can reduce the other 12 volt power converters this would be the ideal solution. A single plug would be such a wonderful thing! Right now I have 8 wall warts so those would go away. \$\endgroup\$ Jun 10, 2016 at 3:11
  • \$\begingroup\$ Like I said it will almost certainly be fine to connect one of your hots to the "L" terminal, one to the "N" terminal and set the switch to 220V mode. Given that your supply is 30A I would also suggest fitting a pair of fuses in the supply to your PSU to limit the current in the event of a fault. \$\endgroup\$ Jun 10, 2016 at 12:49
  • \$\begingroup\$ Thanks, Peter! I will take your suggestion on the fuses. \$\endgroup\$ Jun 13, 2016 at 3:13
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As neither current-carrying conductor (L or N) should be connected to ground in the power supply, it can be used on a US 220 Volt circuit when set to 220 volts.

However, why would you want to do this? - 360 watts is an easy load for a normal 120 Volt outlet.

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  • \$\begingroup\$ Great question! In this project I have a 240 volt, 30 amp line in to run the Silicon Controlled Rectifier using zero-crossing to make a variable heating element. Then I have 8 12 volt adapters to power everything from the thermoelectric cooling modules to fans, sensors and the various microcontrollers that run the system. I am in power cable hell and I wanted a single power source to run the whole kit. In theory there is enough juice left over in that 240 line. This unit seemed to answer that problem and so before I blow myself up I thought I'd ask. \$\endgroup\$ Jun 10, 2016 at 3:04

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