does a household circuit breaker have thermal memory?

djmieczk · 02-09-2013, 07:22 PM

FYI - all breakers in the panel are 20A or greater with the exception of that one 15A

rrolleston · 02-09-2013, 07:28 PM

What did this handyman do other than change the breaker when he was there?

rrolleston · 02-09-2013, 07:32 PM

Can you post some pictures are you sure your panel is even rated for tandem breakers?

Toller · 02-09-2013, 07:53 PM

Quote:

Originally Posted by djmieczk

I did not realize that the toaster oven would warm the bimetallic strip of the breaker and then when we use the coffee maker right after that it would cause the breaker to trip.

I didn't realize that either, cause it doesn't make sense.
As long as your appliance is under 20a, you can run it as long as you want and it won't trip.
You can run your toaster for an hour, or your coffee maker for an hour.
Why would running your coffee maker after your toaster oven be worse than running either.

Toller · 02-09-2013, 07:55 PM

Quote:

Originally Posted by rrolleston

Can you post some pictures are you sure your panel is even rated for tandem breakers?

On Square D and Murray you can't install tandem breakers if your panel isn't rated for them. Maybe others can, but I doubt it.

djmieczk · 02-09-2013, 08:03 PM

OK. Here are some photos. My original question was answered but its fun chatting about this.

He was a young guy that claimed to be a journeyman electrician. I believe him. He was a nice guy and I could tell he did this before by how quickly he worked.

He replaced the breaker and came inside to verify we had current in the outlets and started the oven. He mentioned it would be best to have the toaster oven on a dedicated line.

He was in his personal pickup and not in a working van. My belief is that he just did not have a 20A breaker but wanted to resolve my problem without making another trip.

Kyle_in_rure · 02-09-2013, 11:14 PM

Since when were kitchen circuits allowed to be fed with only 15 amps?
If the circuit has 14 gauge wire, it has to remain a 15 amp breaker, but I don't think I've ever seen a house wired with a 15 amp kitchen circuit.

No wonder the breaker was tripping...

rrolleston · 02-09-2013, 11:21 PM

I don't see that panel being listed to accept tandem breakers. Also possible counterfeit breaker.

k_buz · 02-09-2013, 11:29 PM

edit...

Kyle_in_rure · 02-09-2013, 11:34 PM

Quote:

Originally Posted by rrolleston

Also possible counterfeit breaker.

I was thinking the same thing...

rrolleston · 02-09-2013, 11:41 PM

What state are you from?

k_buz · 02-09-2013, 11:56 PM

Quote:

Originally Posted by Kyle_in_rure

I was thinking the same thing...

I don't think Square D panels have any protection from installing tandems. Every Square D panel I have been in could physically fit tandem breakers even if the panel wasn't listed to.

Kyle_in_rure · 02-10-2013, 12:53 AM

Quote:

Originally Posted by k_buz

I don't think Square D panels have any protection from installing tandems. Every Square D panel I have been in could physically fit tandem breakers even if the panel wasn't listed to.

I meant about it possibly being a counterfeit breaker. I agree with that as well, though. I once installed a tandem in a 1980 square D panel that was unlisted for them, and it fit fine.

JohnnyB60 · 02-10-2013, 01:29 AM

Standard residential breakers have +- 10% rating so a 20amp breaker may not trip at exactly @ 20 amp and as they wear out they get weaker.

CarpenterSFO · 02-10-2013, 04:05 AM

QO breakers are dual magnetic/thermal. As for the counterfeit question, the one in the pic looks just like a genuine QO tandem - no SQUARE D logo, very generic. I have one on my desk right now - no logo printed on front, exactly those stampings. QO online catalog looks same.