Can I use some kind of plug in transformer to convert my 110V wall sockets to 220V to power a 30000 BTU air conditioner safely? The idea is to put in a 220V window unit in the same room as my central air conditioner and use the fan on the central to pull the cold air in to save electricity. If it gets too hot I can turn them both on.

  • 1
    \$\begingroup\$ (The way to save electricity with an AC is to use it to pump heat into the conditioned space instead of just dissipating the energy there. Check measures such as providing shadow, painting a more (IR) reflective colour, improving thermal isolation before upgrading your central AC.) \$\endgroup\$
    – greybeard
    Mar 7 at 7:07

1 Answer 1


No, because your 110 (actually 120) volt outlet won't produce enough power. A 30,000 BTU AC will draw around 2,500 watts of power.

A 120 volt 15 amp circuit (typical in US households) will only produce 1,800 watts. If you happen to have a 20 amp circuit, you still will only get 2,400 watts which might be just enough except that you will need to derate the circuit by 20% for a continuous load. Also, if you have anything else on the circuit, you will be over!

You just don't have enough power for the AC unit.

finally, even if you had enough power, the cost of a transformer of that size would be astronomical. You'd be better of buying a smaller AC unit that would run of 120 volts.

  • \$\begingroup\$ And what's more, a modern A/C will be significantly more efficient, and need less power for the same BTUs. \$\endgroup\$ Apr 5 at 6:14

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