Undersized breaker

[Danny Pritchard]

I always check the data plate on A/C units for the breaker size.Usually I find the breakers to be bigger than what is specified by the manufaturer.Today I found one that was undersized.The max. breaker to be used was 35 amps and the minimum breaker was 25 amps.There was a 20 amp breaker installed in the panel.Since these limits are specified by the manufacturer I called it out.

I understand the problems assosciated with an oversized breaker.What would be the problems with one undersized?This was a 7 year old heat pump with no apparent problems.

[Jim Morrison]

I'm hoping someone smarter than me will jump in and correct me if I'm wrong, but the only issue I can imagine an undersized breaker presenting is nuisance tripping. I'd point it out to my client like you did, but I don't think it could do any harm.

[Brian G]

Have you noticed how many of those *#@$%# things have an odd size specified. It's 35 instead of 30 or 40. You can get a 30 or 40 easily, but a lot of places don't stock "tweeners". As far as I know, most manufacturers don't make many either, other than a 15 amp. They almost invite the contractor to up-size the breaker. [:-irked]

Brian G.

[Jerry Simon]

Brian...and how about the goofy "minimum" ampacity supplies specified, for example, 31.2 amperes??? This is seen quite often.

[Danny Pritchard]

"I'm hoping someone smarter than me will jump in and correct me if I'm wrong, but the only issue I can imagine an undersized breaker presenting is nuisance tripping. I'd point it out to my client like you did, but I don't think it could do any harm."

Jim Morrison

Lancaster, MA

Thanks for the comments Jim.Besides any problems assosciated with an undersized breaker is what a home warranty company would say if a problem arose and the breaker was not as specified.Most buyers in this area get home warrantys. I know if the breaker is oversized and there is a problem they could void the warranty.I don't want to give them an out on fixing a problem because of an undersized breaker.

[chrisprickett]

I've seen whole towns blown up off the map because of an undersized breaker. If I'm not mistaken, an undersized breaker caused WWII.