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ThreeTaps · 09-30-2009, 03:11 AM

Hi all,

I know the rule is to not use either of those to power a window A/C unit, however there are no power receptacles within 20 feet of where my A/C unit will be for my fermentation chamber. So I picked up a 25' medium duty extension cord and a good power strip today, and want your opinions on using them. I figured as long as the ratings for the strip and cord surpass what the A/C unit uses, it would be fine.

A/C unit: 500W, 115V, 4.6A
Extension Cord: 1625W, 125V, 13A
Power Strip: Way above both of those (200A and something like 500V)

I can skip usage of the power strip, or get another extension cord for it if that would be better. I need one however for the light inside the chamber and a mini fan to help circulate air.

TheBelly · 09-30-2009, 03:52 AM

The power strip probably has a 15a cb.
The 500V rating is probably the maximum spike it can take. a 200A power strip would have like power cord the size of the power lines you have running to your house, about the same diameter as a penny.

I would suggest plugging in the extension cord and running the unit for a while under load. Checking it periodically for heat, especially near the outlets.

I have had extension cords burst into flames while running heavy loads for extended periods like my compressor.

Edit: Most house hold outlets are 15AMP. See if you have a 20AMP maybe in your garage.

ThreeTaps · 09-30-2009, 04:22 AM

Quote:

Originally Posted by TheBelly

The power strip probably has a 15a cb.
The 500V rating is probably the maximum spike it can take. a 200A power strip would have like power cord the size of the power lines you have running to your house, about the same diameter as a penny.

I would suggest plugging in the extension cord and running the unit for a while under load. Checking it periodically for heat, especially near the outlets.

I have had extension cords burst into flames while running heavy loads for extended periods like my compressor.

Edit: Most house hold outlets are 15AMP. See if you have a 20AMP maybe in your garage.

I think I'm just going to buy an A/C or appliance extension cord at Home Depot tomorrow. Not worth the risk using this one, even though it "should" do the job fine. I'll then use this one for the power strip to power my fan and light.

Thanks for the input!

Sawdustguy · 09-30-2009, 03:25 PM

Quote:

Originally Posted by TheBelly

Edit: Most house hold outlets are 15AMP. See if you have a 20AMP maybe in your garage.

Why does he need a 20 amp breaker to run an appliance that draws only 4.6 amps? A 15 amp breaker will handle 3 times the load of the air conditioner providing he has nothing else on that circuit.

david_42 · 09-30-2009, 03:35 PM

Quote:

Why does he need a 20 amp breaker to run an appliance that draws only 4.6 amps?

I can't imagine an A/C unit would have a starting current four times the running value, but that would be the only rational for a 20 amp circuit. I'm running a 7 amp A/C on a 15 amp circuit and don't see any problems.

leboeuf · 09-30-2009, 05:13 PM

Window a/c's are designed and meant to be ran on run of the mill 15amp setups. You may not want to run a hair dryer/space heater on the same breaker while the unit is on.... You'll be fine, just use 15amp rated stuff (basically anything you'll find at the hardware store). There's no issue with using extension cords and power strips as long as you aren't tripping breakers.

Reedwalker · 09-30-2009, 05:23 PM

My parents had a house fire doing this exact thing. A window A/C unit on a 25' medium duty extension cord.

If you love your home, family, and pets DO NOT use an extension cord on a A/C unit.

The breakers NEVER tripped. The wiring inside the wall started the fire.

leboeuf · 09-30-2009, 05:29 PM

If the wiring inside the wall caught fire then the extension cord probably wasn't the problem...

Heat only builds if you encounter a resistance in the wire, this can happen at plugs/etc if they start to break down. A fire inside the wall is usually caused by breakdown of the wire or a bad junction.

Reedwalker · 09-30-2009, 05:43 PM

Exacerbated by the heat from the cord. Direct from the Fire Marshall's lips.

Funny how you get on the internetz and everybody is an electrical engineer that specializes in thermal dynamics.

leboeuf · 09-30-2009, 06:00 PM

I'm not a fire marshall, but I am an EE. I worked in the industrial field before I moved on to IC world.
There's no mysticism here. besides the wiring in the wall being solid core and the extension cord being stranded, there really isn't anything else. In the scheme of things the extension cord is no different than the cord on the ac unit...

Any chance you're speaking about a unit that pulls around 20amps?

If this does worry the OP it wouldn't be hard to hook up a longer wire directly to the unit /shrug