Should I use a 12-gage, 20-amp extension cord for this application?

In My Humble Opinion
1

Home electric-savvy Dopers: we are in the process of installing a room air conditioner for a small room in our house. It is a 6,500 BTU Zenith unit (ZW6500R).

We discovered that we will have to get a six to nine foot extension cord for it, and it would need a 15-amp cord (according to the manufacturer - the amperage listed for the appliance is 6.1 amps). Today I went to the hardware store, looking for heavy-duty extension cords.

They had a 14-gage, 15-amp cord which says it is to be used for air conditioners (among other things). That was the heaviest one they had.

It seems to me that using the 15-amp cord is just satisfying the minimun requirement. I’m wondering if I should order a 12-gage, 20-amp extension cord instead (like this), or if I’m making too much of a big deal out of it.

I understand that extension cords are frowned upon for air conditioners; that’s why I’d like to make sure I do the best I can in this situation.

Thanks in advance!

2

I would have no problem using a 15A extension cord on an appliance that draws 6.1A.

3

Fourteen gauge wire suuuuuucks. It will get warm, and your motors won’t last as long, and your breakers will trip. Specially there in Mississippi. I would use a twelve gauge, three-wire cord. I think they make 'em flat for microwaves and such, and with the angled plug so you can make the wire go straight down the wall.

:slight_smile:

How are things down there? It got up to ninety today.

4

Go for the 12-gauge.

If you don’t mind bright orange, you can find 12-gauge cords intended for use with power tools at most good hardware stores.

Pay attention to the plugs - the one you linked is for 240 volts, but your AC may be 120 volt, and the plugs are incompatible.

5

Voltage drop over a #14 conductor at the given distance is negligible and no worry provided that’s the only load on the cord.
A 20 amp cord at 120 V may have a plug that won’t match a standard 15A wall outlet.

6

[QUOTE=DistendedPendulousFrenulum]
Fourteen gauge wire suuuuuucks. It will get warm, and your motors won’t last as long, and your breakers will trip. Specially there in Mississippi. I would use a twelve gauge, three-wire cord. I think they make 'em flat for microwaves and such, and with the angled plug so you can make the wire go straight down the wall.

:slight_smile:

How are things down there? It got up to ninety today.
[/QUOTE]

Errr. Assuming it’s plugged into a 15 amp circuit, all the wire between the panel and the plug is 14 gauge. Using a short 14 gauge extension cord is no different than plugging the AC into an outlet slightly further from the panel.

7

[QUOTE=Gorsnak]
Errr. Assuming it’s plugged into a 15 amp circuit, all the wire between the panel and the plug is 14 gauge. Using a short 14 gauge extension cord is no different than plugging the AC into an outlet slightly further from the panel.
[/QUOTE]

A wall outlet better not be on a fifteen amp circuit. And even if it is, most building codes specify twelve-gauge. Even Shitty Ass Shelby County only allows fourteen gauge for lighting circuits.

8

[QUOTE=DistendedPendulousFrenulum]
How are things down there? It got up to ninety today.
[/QUOTE]
Feet of snow? :smiley:

Things are much more peaceful, after our Fun With Drunks in the ICU on Sunday.

I did, but they were all 25 ft or greater in length (not counting the various 2-foot long things like squids).

[QUOTE=Carson O’Genic ]
A 20 amp cord at 120 V may have a plug that won’t match a standard 15A wall outlet.
[/QUOTE]
That didn’t even occur to me, but I found out the hard way. I went all the way to Clinton to the one place which had a ‘12 gauge appliance cord’ only to find that it had blades like - | instead of | | .

[QUOTE=Gorsnak]
all the wire between the panel and the plug is 14 gauge.
[/QUOTE]

[QUOTE=DPF]
most building codes specify twelve-gauge.
[/QUOTE]
Lawd. I guess I’d better be finding out what’s in the circuit.

9

The amperage didn’t sound right so I looked it up and it is correct. My 5000 btu unit will warm up the cord a little (3 ft extension). It’s a heavy duty cord but that circuit has a lot of stuff on it. I have to run my laser printer on another circuit.

10

[QUOTE=DistendedPendulousFrenulum]
A wall outlet better not be on a fifteen amp circuit. And even if it is, most building codes specify twelve-gauge. Even Shitty Ass Shelby County only allows fourteen gauge for lighting circuits.
[/QUOTE]

There were a lot of houses built before that became chapter & verse of the NEC.
11

[QUOTE=beowulff]
I would have no problem using a 15A extension cord on an appliance that draws 6.1A.
[/QUOTE]
Hubby’s concern is that the extension cord is ‘braided wire’ - he fusses about the voltage drop being hard on the compressor.

He’s leaning towards making a wire from Romex and some plug ends. The advantages of this would be that the wire would match that of the circuit and would only be as long as was necessary.

[QUOTE=Magiver]
The amperage didn’t sound right so I looked it up
[/QUOTE]
I was kind of surprised at that, too. This is not my father’s air conditioner.

[QUOTE=Carson O’Genic]
There were a lot of houses built before that became chapter & verse of the NEC.
[/QUOTE]
The question becomes, what was put in when Hubby & his first wife had the house built. He thinks it was 14-gauge. I looked for any little exposed wiring to check, but have found none so far.
**
Distended Pendulous Frenulum** came and did some wiring when we remodeled (maybe he remembers what gauge that was), but that’s not really pertinent - this is the old part of the house.

12

[QUOTE=NinetyWt]
Hubby’s concern is that the extension cord is ‘braided wire’ - he fusses about the voltage drop being hard on the compressor.

He’s leaning towards making a wire from Romex and some plug ends. The advantages of this would be that the wire would match that of the circuit and would only be as long as was necessary.

I was kind of surprised at that, too. This is not my father’s air conditioner.

The question becomes, what was put in when Hubby & his first wife had the house built. He thinks it was 14-gauge. I looked for any little exposed wiring to check, but have found none so far.
**
Distended Pendulous Frenulum** came and did some wiring when we remodeled (maybe he remembers what gauge that was), but that’s not really pertinent - this is the old part of the house.
[/QUOTE]

Romex and plug-ends is overkill - and potentially dangerous since it’ll be stiff and stick out and get caught on stuff. I did this as a “test harness” for some wiring in a barn and it’s hard to work with when you’re done.

Check the breakers. If they’re 15 amp, it’s probably 14 guage wire. That’s the matched rating. If it’s 12-gauge, you’ll probably have 20A breakers.

All that said, if you’re motor is rated for 6A, it’ll draw more than it at startup but then drop rapidly back to 6A.

Your breakers won’t trip for running thin cord. You breakers will trip if you’re drawing too much amperage. Thin cord will not cause you to draw too much amps; if anything, it’s the opposite. That’s simply wrong.

Don’t worry about braided cord, they take the braid into account when they calculate guage. It’s more flexible and easier to work with. A lot of commercial buildings are wired with stranded cord now, it’s easier to pull across long distances.

Just get a good 14G cord, it’ll have enough capacity.

This is UL listed, OSHA rated and only $8.

13

Belrix, that looks suspiciously like the one I purchased, although I got a 9-foot one. It is UL listed, 14/3, 15 A, 125 V, 1875 watts. It was $9.99.

Re: the home-made cord: I think his plan was to run this within a conduit of some kind, along the top of the baseboard. It would still be stiff and harder to work with, and we’d have to go buy the male & female ends.

The breaker for that room is 20 amps.

I also found a monster roll of Romex under the sink which is 12/2, so - I’m thinking that’s what we used for the remodeling; and possibly what was used in this older circuitry.

I also found a replacement cord for a dryer (who knows where it’s from). I mischeviously thought of telling Mr. Worry-wart to use that for his cord. It’s gotta be 10 gauge. Heh.

14

[QUOTE=NinetyWt]
Belrix, that looks suspiciously like the one I purchased, although I got a 9-foot one. It is UL listed, 14/3, 15 A, 125 V, 1875 watts. It was $9.99.

Re: the home-made cord: I think his plan was to run this within a conduit of some kind, along the top of the baseboard. It would still be stiff and harder to work with, and we’d have to go buy the male & female ends.

The breaker for that room is 20 amps.

I also found a monster roll of Romex under the sink which is 12/2, so - I’m thinking that’s what we used for the remodeling; and possibly what was used in this older circuitry.

I also found a replacement cord for a dryer (who knows where it’s from). I mischeviously thought of telling Mr. Worry-wart to use that for his cord. It’s gotta be 10 gauge. Heh.
[/QUOTE]

I think you’re perfectly safe. You’ve got 6A of appliance on a 15A cord on a 20A house circuit.

You’re good. Sleep the sleep of the righteous on this one.

15

If he is going to run it in conduit, individual wires (THHN or similar) will be easier to install, and run cooler than romex.

“SO” is the prefered cable type for building custom extension cords…it is tough enough not to need conduit.

16

AFAIK, it’s against code to run Romex in conduit…

17

[QUOTE=beowulff]
AFAIK, it’s against code to run Romex in conduit…
[/QUOTE]
This is a bit of an electrical urban legend. It’s OK to run romex in conduit subject to certain limits. Short runs with conduit intended for no more than protecting the romex is usually fine. Use of metal conduit requires bushings at the ends to protect against the wire chaffing.

NEMA code is online if you want to go searching…