Window air conditioner with extension cord safe?

Question

Is is a big safety hazard to plug a 5000 BTU air conditioner into a heavy duty 6 ft or 12 ft extension cord and then plug that extension cord into the wall?  I know the manufacturers do not recommend this, but I was wondering if anyone has done this and did it work out well for you?

I have an Indiana rental home where the central air conditioner just  quit working and I have decided to give the tenants some window A/C units instead of replacing the old one due to cost.  They prefer 3 small units (one for each bedroom) rather than a large unit in the living room and one in the kitchen. I just discovered one of the bedrooms does not have an electric outlet next to the window.  So I'm trying to figure out a solution, and I think it would take at least 2-4 weeks to find an electrician to do a small job like adding one electric outlet to this room.  Plus might be several hundred dollars. Thanks for any input!

Nathan Gesner · Answer

Look at the air conditioner label or user manual. It will tell you how many AMPS the A/C unit uses. Then go to the hardware store and ask for an extension cord rated for the number of amps required, or better. These tend to be shorter (10 feet or less) and heavy duty (12 - 14 gauge wire).

Richard F. · Answer

You would need to check the manufacturers specs for a specific unit, as it certainly will vary based on size from one manufacturer to another. Also, the age of the unit comes into play. Expect 500 watts additional surge, or starting load, above the "running" load. To get perspective, a typical blow dryer for hair is usually 1600 watts or more. Most average computers are around 5 watts, but Gaming computers can get quite high with the video hardware. Clock radio and night lamps are minimal. Generally, anything that creates heat is using a lot of wattage...curling irons, coffee pots, microwave oven, crock pots, etc. Every device should have a tag on it that shows watts or amps. google a conversion calculator to convert amps to watts.

The limitation for your existing circuits is primarily the actual wire leading from the panel to the outlet. You may need to completely rewire or deal with the limitation. You should be aware also that a typical home wiring is not organized neatly, room by room, with regard to individual circuits. They usually each cover PART of multiple rooms. AC's in adjacent bedrooms could end up on the same circuit, which will cause problems!

TOTAL panel capacity can be increased, and additional new circuits can be added, depending on exactly how old and what condition the existing is in. You should only seek a licensed and properly insured electrician for this type of work. They may find that the only safe option is complete rewire, or they may be able to add a sub-panel for additional circuits. It will take some investigation on their part to determine this. Permits should be obtained for most, if not all of these options depending on your locale.

Tricia O'Brien · Answer

@ Richard F.

Thanks for your reply!

What is the typical starting Watts for a window air conditioner? If ,for example, the starting watts for the window air conditioner was 2,500 watts and there's also a computer , a clock radio and two night table lamps on the same circuit how do I determine the total load the tenant wants to put  on that  circuit?  Can an electrician do some work on the electrical panel to increase the capacity of a circuit ( say to 6000 watts) without digging into the walls?

Window air conditioner with extension cord safe?

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