I have some equipment that uses 8.5 amps and 1050 watts on a 110v. Any idea what the amperage would be on 208 three phase?

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    \$\begingroup\$ 8.5A at 110V is not 1050W. \$\endgroup\$ – Eugene Sh. Jan 16 '18 at 17:30
  • \$\begingroup\$ The watts fluctuate, ~1,000 watts \$\endgroup\$ – dzm Jan 16 '18 at 17:33
  • \$\begingroup\$ How are you going to connect your present single-phase equipment to the three-phase source? \$\endgroup\$ – Peter Bennett Jan 16 '18 at 20:39
  • \$\begingroup\$ Unclear what you are asking. It sounds like you have two computer power supplies, that presently are plugged in to a 120V outlet. And, perhaps they are "agile," switching PSUs that can handle a wide range of input voltages. And, perhaps you are asking how much current each one will draw when plugged in to a single phase of a 208V circuit. Is that what you are asking? Or, is it possible that your PSUs are designed for a server room, and can use all three phases of the 208V circuit? \$\endgroup\$ – Solomon Slow Jan 16 '18 at 21:01
  • \$\begingroup\$ @jameslarge Exactly, many data centers use 208v three phase. So I'm just trying to determine approx. amperage if I plugin into that vs a 110v. Like if I plug into 220v, then my amp. is halved (again, not an expert, but roughly), so just wondering what it would be on 208v three phase, but it sounds like I may just need to plugin and see. \$\endgroup\$ – dzm Jan 17 '18 at 18:42

A 208 volt 3 phase supply has line voltages of 208 volts and a phase voltage (line to neutral) of 120 volts as per this diagram: -

enter image description here

So, if your equipment can run from line to neutral and is just a passive load like a heater then the watts will tend to increase a little bit more as its supply voltage increases from 110 V to 120 V.

If the equipment is more sophisticated then it may be slightly more power efficient or slightly less power efficient at 120 V compared to 110 volt but this cannot be determined by the detail in the question.

Even if it were known what the equipment precisely is, there may be no data available that shows what power consumption it will have at 120 volts compared to 110 volts.

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  • \$\begingroup\$ Thank you for this explanation. Is there anyway to approximate the amperage used here? \$\endgroup\$ – dzm Jan 16 '18 at 18:03
  • \$\begingroup\$ I'm not going to get involved in a guessing game. The current may be more or it may be less than that taken from a 110 volt supply. There is no information that can lead me to conclude anything different. \$\endgroup\$ – Andy aka Jan 16 '18 at 18:12
  • \$\begingroup\$ Ok I see, I really don't know enough about this. Is there any other information that can be used to calculate this that I'm able to provide? \$\endgroup\$ – dzm Jan 16 '18 at 18:15
  • \$\begingroup\$ I have no idea what information you are able to provide about the equipment. I have no idea (that on further investigation of the equipment) if there is any new data that may surface that gives you a specific answer to your question. \$\endgroup\$ – Andy aka Jan 16 '18 at 18:18
  • \$\begingroup\$ The equipment is 6x RX 580 GPU's, using two 750 watt PSU's. Not sure if that's helpful. \$\endgroup\$ – dzm Jan 16 '18 at 18:22

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