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Old 02-14-2020, 05:51 AM
Loyuod is offline
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Does some voltage drop damage Portable air cons?


If I run a 240V portable AC unit off a long extension cord with a 10-12V drop, is this bad for these units? Maybe only the cheap brands?
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Old 02-14-2020, 07:24 AM
Bill Door is offline
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Your air conditioner is probably going to be fine down to 208 volts or so, but I'm worried about your extension cord. 15 amps at a 12 volt drop means the cord has to dissipate 180 watts of heat. What gauge extension cord are you using and how long is it?
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Old 02-14-2020, 07:34 AM
Loyuod is offline
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Quote:
Originally Posted by Bill Door View Post
Your air conditioner is probably going to be fine down to 208 volts or so, but I'm worried about your extension cord. 15 amps at a 12 volt drop means the cord has to dissipate 180 watts of heat. What gauge extension cord are you using and how long is it?
Hi,

It's a standard A/C unit with a 10A plug, you plug into house power point. My extension cord is 50Metres of 1.5mm2. volatge calc shows 11V drop irrc.
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Old 02-14-2020, 07:39 AM
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It's not going to help it's longevity. Anything it doesn't get in voltage is made up in current and that's what produces heat. Also your 220V may not be constant as it is. You are really pushing the limit of the cord, consider upgrading the cord to a thicker gauge as a quick fix.
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Old 02-14-2020, 07:48 AM
Loyuod is offline
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Quote:
Originally Posted by kanicbird View Post
It's not going to help it's longevity. Anything it doesn't get in voltage is made up in current and that's what produces heat. Also your 220V may not be constant as it is. You are really pushing the limit of the cord, consider upgrading the cord to a thicker gauge as a quick fix.
Thanks, I do have a 2.5mm2 cord but it's so hard big and hard to roll up.
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Old 02-14-2020, 07:52 AM
Bill Door is offline
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Quote:
Originally Posted by Loyuod View Post
Hi,

It's a standard A/C unit with a 10A plug, you plug into house power point. My extension cord is 50Metres of 1.5mm2. volatge calc shows 11V drop irrc.
Wait, my experience, such as it is, is only in American wire gauge (AWG), but when I look it up it looks like that converts to a 16 AWG. Are you really planning to run 50 meters of 16 AWG extension cord to a 2,200 watt air conditioner? Around my house 16 AWG is speaker wire. You better consult an real electrician, I feel like you're starting to get into trouble.
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Old 02-14-2020, 08:46 AM
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Also consider that the inrush (startup current ) is typically 2 to 2.5 times the operating current.
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Old 02-14-2020, 10:40 AM
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A 50Metres of 1.5mm2 extension cord on offer fr Amazo UK has the following advice:

Quote:
* Cable 50m x H05VV-F 3G1.5mm2 - 3120 watts when cable is unwound from the reel

* 1000 watts when left as wound on the reel - Cable Length: 50 m - Wattage: 3120 W

* Maximum Load: 13 A - Length: 280 mm - Width: 210 mm - Depth: 360 mm - Voltage: 240 V
Remember that with 240 volts, we need less copper to get the power.

Last edited by bob++; 02-14-2020 at 10:41 AM.
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Old 02-14-2020, 12:39 PM
Bill Door is offline
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I know that the 240 volt requires less copper, but I worry about dissipating that much heat. It's 5% of the total energy used by air conditioner going to heat the extension cord used to power it, plus, it all turns to heat increasing the load to the air conditioner itself. If it's only 10 amps rather than the 15 I estimated it's still 120 watts of heat. Think how much heat two sixty watt incandescent bulbs throw off. You couldn't leave the wire coiled up, it just seems like a kludge. For a short term solution maybe, but you sure don't want to think it's a permanent thing.
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Old 02-14-2020, 01:33 PM
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Quote:
Originally Posted by Loyuod View Post
It's a standard A/C unit with a 10A plug
Which means the steady-state current is probably less than 10 A.

You need to look at three things:

1. Knowing the steady-state current and gauge of the extension cord, how much heat (per unit length) is being generated by the extension cord during operation? Too much self-heating by the extension cord is dangerous. There are guidelines on this. Ambient temperature is also a factor; the max current the extension cord can handle decreases as the ambient temperature increases.

2. Knowing the steady-state current, and length & gauge of the extension cord, what's the voltage drop of the extension cord? Too much voltage drop can burn up a motor.

3. As noted by am77494, there is also the issue of voltage drop due to inrush current. This is a function of the magnitude of the inrush current along with the length & gauge of the extension cord.

What is the manufacturer and model number for the unit?
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Old 02-16-2020, 05:27 AM
Melbourne is online now
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Does the A/C have an actual voltage rating on the label? Sometimes min-max values are given.

FWIW, running the A/C when the voltage is "too low" will burn out the motor. Many things rated for 240V are actually rated for 220-5%. Make and model?

Last edited by Melbourne; 02-16-2020 at 05:27 AM.
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