Home Wiring Q: Extension Cord As Inductor to Prevent Breaker Tripping?

[Jonathan S.]

Internet searches yield plenty of results about how suspect extension cords trip breakers.
But I seem to have the opposite situation, and found an explanation that an extension cord can act as an inductor.

The culprit is a rather innocuous window AC unit:
https://www.homedepot.com/p/GE-Profi...06BC/319294010
Always trips the breaker, tried probably half-a-dozen times, after only several minutes, no cycling on/off or anything like that.

Breaker is 15a, received a clean bill of health from a electrician who implemented some upgrades (including the replacement of mismatched breakers) after I bought this [ski] house in the spring (especially installing a subpanel in the detached garage to support an EV charger, where previously the detached garage was pigtailed into the breaker for the smoke alarms).

Texted the electrician about this -- replied that arc fault breakers are "notorious" for being tripped by AC (or vacuum).

As a short-term workaround, I grabbed a random outdoor extension cord of unknown origin, and plugged the AC unit into the bathroom outlet, which worked fine.
Electrician said running the AC unit off of as short-as-possible 12awg extension cord is fine.
Then out of curiosity, I plugged the extension cord into another bedroom outlet, which has the same type of breaker, but is not tripped by the AC unit.
Hmm.
Plugged the extension cord back into the adjacent outlet. Breaker did not trip. Even after hours of testing. Unplugged the AC unit from the extension cord, plugged it back in but directly into the outlet, almost immediately tripped.

So until the electrician can come back to see if a breaker upgrade might help, should I:
Keep running the AC unit off of this long and loosely coiled outdoor-style extension cord?
Trying running it instead off a to-be-purchased extension cord, like this: https://www.amazon.com/gp/product/B0CBP4S2SL/ ... and see if that still serves enough of an inductor role, with less potential for heating up?

In answer to the anticipated question of whether the loosely coiled extension cord was heating up, unfortunately I forgot to check that.
(Even though I do have a temperature gun, from when I was temporarily running mobile EVSE off the dryer outlet, which was amazingly located so conveniently near a window adjacent to the driveway.)
I'm also not up there right now, and won't be for awhile (heading out for the SW Chutes on Sunday), but other people will be staying there while I'm away.

TIA for informative replies or even just amusing banter (and apologies in advance if any of this comes across as especially clueless).

Pics, okay, here's the breaker, #6 (with picture rotated 90 degree for some unknown reason):






And here's the Mt Washington summit yesterday -- didn't have time to wait my turn for the selfie right at the sign, since I was trying for a sub 3 hr Cog base > summit > Cog base (which I made with a whopping three minutes and thirty-five seconds to spare), but I did tag the summit cairn after taking this picture to make it official:

[Core Shot]

A 12 gauge extension cord is enough for a 20 amp load. Assuming it’s not crazy long. Running an extension cord on a 15 amp breaker is fine

I think it’s the electrician following current code and using arc fault breaker. They suck.
If there isn’t another load on the circuit then it’s the damned breaker.
Just reread that the other breaker is arc fault. And it doesn’t trip. That’s odd. What happens if you use the extension cord on the close outlet? Maybe there it’s an induction thing? Wild.

It’s not hard to pull a breaker without getting electrocuted
Replace it with the old one. Or a non arc fault 15 amp.

PS. Nice mt Washington ski stoke.

PPS. I’m not a sparky. But I have wired a lot of shit.

[I Skied Bandini Mountain]

Bad a/c plug. You could work down the line and replace the breaker and then receptacle, but I'm betting it's the plug. Sometimes the way they hang off the receptacle makes a difference compared to laying on the floor connected to an extension. FWIW, newer AFCI breakers aren't as touchy as first gen, depending on how old the OG breaker is, you might consider changing that out. If you wanted to eliminate all possibilities and not fuck around, consider changing out the breaker, receptacle, and plug, and go run up more mountains.

[singlesline]

Now I want to go try an extension cord...

Both arc fault breakers serving my kitchen outlies love to blow.

The Ninja flip air fry/toaster oven thing will blow it during preaheat on "Air Roast" mode, but not "Air Fry" (which uses a faster fan speed) or other modes...if I preheat on another setting and then switch to "Air Roast" then it won't blow and works fine.

Vitamix blender will pop it them at full speed. Not always, just on occasion.

Sous Vide stick will blow it when first warming up, but if you reset it enough times and/or get lucky it will then be fine to run at any temp. Seems like if it works for more than a minute, you'll be good for an entire cook. It only has an 800W heating element and other than that it is just running a small motor and PID controller...shouldn't really be blowing breakers.
Are the wires inside my wall warming up and then they get happy after they've had some current flowing through them?

[I Skied Bandini Mountain]

Brushed electric motors in hair dryers, blenders and vacuums, and first gen AFCI breakers don't like each other very much.

You should have GFCI breakers (or outlets) serving your kitchen area and appliances. AFCI are for living areas. AFCI in the kitchen would be a constant headache.

Someone mentioned above that newer AFCI breakers are not as problematic as the first gen. Am I just talking into the void here?

[Jonathan S.]

A 12 gauge extension cord is enough for a 20 amp load. Assuming it’s not crazy long. Running an extension cord on a 15 amp breaker is fine

I think it’s the electrician following current code and using arc fault breaker. They suck.
If there isn’t another load on the circuit then it’s the damned breaker.
Just reread that the other breaker is arc fault. And it doesn’t trip. That’s odd. What happens if you use the extension cord on the close outlet? Maybe there it’s an induction thing? Wild.

It’s not hard to pull a breaker without getting electrocuted
Replace it with the old one. Or a non arc fault 15 amp.

PS. Nice mt Washington ski stoke.

PPS. I’m not a sparky. But I have wired a lot of shit.

The AC window unit runs fine, no breaker tripping, even after hours of continuous running, when plugged via the random outdoor extension cord into the:

• guest bedroom with 15a arc fault breaker (long extension cord piled up into a loose coil),
• master bedroom with seemingly identical 15a arc fault breaker (extension cord probably was doubled-up or tripled-up along much of its length, since not a far distance, but the cord is long), or
• bathroom GFCI (ditto)

But when plugged directly into the guest bedroom outlet, trips after just several minutes, and after many trials (i.e., not one of those intermittent failures that can be difficult to replicate).
I did not try plugging the AC directly into any other outlet, since that would require removing the unit from the window, where I set up all the insulation etc. just right.
The EV charger was not in use at the time of any of this testing, which means that the total electrical load on the house was rather minimal (i.e., probably just a few lights plus a bathroom fan).

So the addition of extension cord is somehow preventing the tripping on the guest bedroom breaker.
Which seems to be a perfectly fine temporary fix.
Although as a permanent fix, seems kind of ... strange.

Both of the 15a breakers (i.e., guest bedroom and master bedroom) are probably original from 1998.
The house received many upgrades since then, although some of them were really half-baked (e.g., pig-tailing the addition of a detached garage into the smokes breaker, adding a deck hot tub in an ever worse way, installing a break of a different brand than the panel).
All of those items have been fixed by the electrician.
(Side bar: the panel is only 100a even though the service is 200a. Still a free slot though in the panel, and the garage service was upgraded to be served by a 100a subpanel. So that lame 100a panel is not a directly concern, but does show than the original 1998 design was done on the cheap in many ways. The house was even foreclosed on in 2008, then the interior was ripped down to the studs in 2012, and rebuilt to an extent that it's nicer in many ways than our main residence!)

But all that does point to the breaker as perhaps being the culprit.
Would replacing it with a 20a breaker make any sense? Or is that a potentially bad mismatch?
Either way, I see that replacement GE breakers from Home Depot are nearly free, and my brother-in-law (lots of experience with major home renovations, although only basic wiring) reassures me such a replacement is very simple. (The main power shutoff to the house is conveniently located adjacent to the panel.)

So seems like that would be a fix I can do myself that is, let's see, quick, cheap, safe, and something new, all of which add up to my idea of a fun home project!

[Jonathan S.]

Bad a/c plug. You could work down the line and replace the breaker and then receptacle, but I'm betting it's the plug. Sometimes the way they hang off the receptacle makes a difference compared to laying on the floor connected to an extension. FWIW, newer AFCI breakers aren't as touchy as first gen, depending on how old the OG breaker is, you might consider changing that out. If you wanted to eliminate all possibilities and not fuck around, consider changing out the breaker, receptacle, and plug, and go run up more mountains.

I like the part about running up mountains!
(Just not running down them though, ugh. I don't understand how elite trail runners do that. Then again, many of them probably don't understand how we can ski down mountains...)

The AC unit plug sure seems substantial, and has a nice fit into the receptable.
I suppose this could be tested by replacing that long outdoor extension cord with an absurdly short 12awg extension cord, so short that any inductor property would be negligible.
That's about as cheap and easy a test fix as possible, so I'll order one.
I'll also try replacing the breaker since that also seems to be cheap and easy.

[Jonathan S.]

[...] Vitamix blender will pop it them at full speed. Not always, just on occasion. [...]

My wife has definitely put that to the test -- her Vitamix should probably come with a warning to use ear protection, but she's never tripped a breaker with it, either at the ski house or our main residence.
Oddly enough, our main residence (2005 construction) has once outlet that is frequently tripped by a vacuum cleaner. But no other outlets in the house are tripped by that vacuum cleaner.

[Jonathan S.]

Looking at the Home Depot results in more detail, the arc fault breaker:
https://www.homedepot.com/p/GE-Q-Lin...AFP2/100674086
... involved a significant price premium.
This makes me think the arc fault breaker in the house is not the original from 1998, but rather from the renovation in 2012, since such breakers were not code until starting in 2002.

[Jonathan S.]

Looking at the Home Depot results in more detail, the arc fault breaker:
https://www.homedepot.com/p/GE-Q-Lin...AFP2/100674086
... involved a significant price premium.
This makes me think the arc fault breaker in the house is not the original from 1998, but rather from the renovation in 2012, since such breakers were not code until starting in 2002.

[Core Shot]

Interesting electrical. Using the extension cord on the same breaker keeps it from tripping? That’s trippy.

Fuck that breaker.
Swap out with non arc fault. If you’re not comfortable working in a hot panel kill the main switch first. Just don’t touch the upper terminals on the supply entry.

Arc breakers suck. GFCI is good for baths kitchens etc. but arc fault is insurance driven. Fuck that.

PS. Swapping a 20 amp for a 15 amp breaker isn’t wise. 20 amp requires 12 gauge wire all the way. And you might have 14 gauge in the walls. If a sparky who knows his shit checks it out, then yeah it can be upgraded.
Houses weren’t burning down from quality breakers before the arc fault code.

[Jonathan S.]

^ Makes sense on 20 vs 15, thx.

I'm probably going to try a 3' 12awg extension cord first, and see if that has the same anti-tripping properties as the long orange outdoor extension cord of unknown origin.

Unless the electrician is able to stop by first. But things take awhile up there! Although "Get It Up Door Service" ("We get it up when you can't") installed the automatic garage door openers within a few days. (Yes, that really is the name of the company and its motto!) And the septic service, which was especially fortunately given the back-up! Otherwise, more like a matter of months for service to second home owners. (Although I can't blame them, and I'm happy that anything related to building trades seems to keep skilled workers gainfully self-employed, especially given nationwide longer-term trends in the opposite direction.)

[nickwm21]

Home Wiring Q: Extension Cord As Inductor to Prevent Breaker Tripping?

Just get a new AF breaker.

What CS is telling you to do is against code. Some codes are stupid… but the people who write the NEC are not stupid…

If a new AF breaker doesn’t solve it, pull it out and return it.

Sent from my iPhone using TGR Forums

[Jonathan S.]

^ Okay, thanks, I'll stick with code (as in, NEC, not NSAA's Your Responsibility Code). I'm flying out tomorrow morning for my final four days of skiing, so probably no updates until I get back up to the house later this month. (To be continued...)

[Core Shot]

Hey Nick. Why is arc fault current code?
Why hasn’t my house burned down? Or the last house. Or the house before that with button fuses?

It’s a non issue. Driven by insurance companies and electrical unions and manufacturers that want to sell you more expensive breakers.

But yeah. If you want to stay current then replace with a new arc fault.

Ps. Did you see that panel has a lot of non arc fault breakers? Probably was a remodel where the building permit required arc faults. But none of the other breakers were required to be “upgraded”

Im all for GFCI. It saves lives. In wet or outdoor areas.