Power on coiled cords

[Darren Wright]

Given the age of our house and it was about 100* today, I was checking some our outlets and our attic for warm spots that need attention. We have portable ac unit running up there on a pretty substantial power cord as there aren’t many outlets. The plugs weren’t all that hot, but the few coils of cord stacked up did catch my eye at the end of the cord. It’s not terribly hot, but as you can see the straighter part is noticeably cooler.


I straightened out the coils and they did cool off. Just thought it was worth a share and a good example of how the inductive nature of a coil can cause heat build up.

 

[Ted Calver]

Good reminder. I’ve often wondered about induction heat in the retractable extension reel supplying my lathe peripherals…lights, sanders,grinders. Are you using the FLIR One on a cell phone?

 

[Darren Wright]

Good reminder. I’ve often wondered about induction heat in the retractable extension reel supplying my lathe peripherals…lights, sanders,grinders. Are you using the FLIR One on a cell phone?

Yes, the one for the iPhone. Caught it on sale on an Amazon prime day sale.

 

[Ryan Mooney]

I’ve often wondered about induction heat in the retractable extension reel supplying my lathe peripherals

When I bought my overhead real I shopped really hard to get one rated for a full 20a under the theory that I'm not generally going to use 20a but it's in the ceiling which is already hotter than the rest of the garage when it's hot and the coiled wire adds risk there. You're probably mostly fine with low (lights) and intermittent (sander, grinder) draw.

 

[Vaughn McMillan]

That's a pretty enlightening photo. My overhead cord reel in the shop typically has only a single sander or router plugged into it, so I think it's OK.

I also use a 25' cord reel for some of our on-stage power distribution with the band, but the things I plug into it have a very low draw. Off the top of my head, I'd guess the load is less than 3 amps. We can run the entire band off a single 15 amp circuit. (We'd prefer a 20 amp outlet, though.) It's not like the old days when I'd tap into the venue's mains with an 80 amp 220v power distro system.

 

[Frank Fusco]

I had never heard this about coiled cords. So, I checked with my son-in-law, a graduate electrical engineer, and he said "yes", coiled cords can overheat. Glad the SIL is good for something.

 

[Jonathan Shively]

My dad had a cord winder that wound an extension cord into a 5 gallon bucket. One day whatever he plugged into it didn't work. Took the top off of the bucket and a gob of plastic molded into a mess. I lay out extension cords since then to use. And I stress to my students and grandkids to wrap up an extension cord only if it is unplugged.

 

[glenn bradley]

Good safety reminder. Dad always taught us to lay cords out and to pull more out of auto return reels than we needed. I assume he learned a similar lesson somewhere along the way and passed it on to us. I just do it out of habit. Plenty of examples.