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If I need ~20A to power a device, but all the available circuits in the building are 15A tops, would I be able to power said device? Perhaps using a UPS and some tomfoolery?

  • What kind of device are we talking here? And on a regular basis? – Machavity Nov 6 '17 at 22:52
  • Consistent power draw ranging from ~1A idle to ~20A maximum (shouldn’t ever be reached) – Bakna Nov 6 '17 at 22:53
  • Can you be more specific on the device? Like a computer? Power tool? – Machavity Nov 6 '17 at 22:56
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    Are these universal voltage? Depending on your wiring you may be able to convert to 240v. This would require some rewiring. The safest method would be to pull a new dedicated circuit. Less electrical noise on the line better for servers. – Ed Beal Nov 6 '17 at 23:12
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    Is this a machine you are designing/buiiding for sale or distribution in several locations? Or do you possess this machine and are trying to make it work in your underpowered home? If the latter, can you definitively find a way to work within a power budget of 1440W continuous? – Harper Nov 7 '17 at 1:50
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Generally, nope. But...

Is this a commercial building, or in Chicago or a few other places? Most likely your wire is in conduit. Pull some 12AWG wire and breaker it properly.

Does the machine come in a 240V version? Is there a circuit in your building that you can knock out without falling below legally required minimum outlet and receptacle locations? Convert that circuit to 240V and use that. You will only need 10A at 240V.

Is it a machine capable of taking multiple power supply inputs? Many server-tier PCs or UPSs are capable of drawing from redundant power supplies, and current-limiting themselves. Internally they convert to DC onto a shared DC bus, which is the only electrical way to gang supply from multiple circuits.

Is it, or can it be broken into, several separate machines on a rack? Nobody cares if 2 servers on a rack are plugged into 2 different circuits.

Is it a welder? Special rules apply.

Is this an older air conditioner? Talk to your power company about whether they have an appliance upgrade program. Often they will buy you a new, efficient air conditioner because it will save X watts of power on the power grid, and that is actually cheaper than building X watts of additional power plant.

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[Can I power a 20A load when available circuits are 15A]

There is no way to provide a continous 20A from one 15A circuit.

This is due to

  • The principle of conservation of energy.
  • Safety rules aimed at preventing your house/building burning down.

Even if I can pull from two separate 15A feeds?

In most jurisdictions, there is no legal way to combine circuits to provide more power to a single load.

The correct way to deal with this is to run a new circuit back to the main panel using wire sized for the load.


See also:

All of which essentially say no.

  • Even if I can pull from two separate 15A feeds? – Bakna Nov 6 '17 at 22:59
  • @Bakna: see updated answer. – RedGrittyBrick Nov 6 '17 at 23:15
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There's no UPS battery that I know of that provides 20A off a 15A plug. There's a real safety issue there. So a UPS battery is not an option as a workaround.

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