So I just found out most of the breakers I've been using are actually only rated for 75% continuous load...

I was looking through some old spec sheets from a job I did in Phoenix last summer and stumbled on a footnote I'd missed from Square D. It says their standard QO breakers are only good for 75% of the rating if the load runs for 3 hours or more. So if I've got a 20 amp circuit powering a grow room or a community hall AC unit that runs all day, I'm way over the limit. Anyone else run into this or am I the only one who missed that fine print?

4 comments

4 Comments

ray_williams1mo ago

Wait wait wait, hold on. 75%? So a 20 amp breaker is basically a 15 amp breaker if it runs for more than 3 hours? That can't be right, that's like half the reason I use breakers at all. I gotta go dig up my old boxes now, this is gonna bug me all week.

phoenix_bailey1mo agoMost Upvoted

Man thats rough. The fine print on those spec sheets can really sneak up on you. Totally feel your pain on missing that detail till it was too late.

emeryj661mo ago

Yeah @phoenix_bailey the fine print always gets you when you least expect it.

murray.cora1mo ago

Oh man, I've been there for sure! The worst is when you think you've read everything carefully and then boom, there's that one line buried at the bottom. What I started doing is reading the spec sheet out loud to myself, it forces me to actually pay attention to every word instead of skimming. Also, I screenshot the important pages on my phone so I can zoom in on the tiny print later when I'm not rushed. Helps a ton to catch those sneaky details before you commit. Hope you can find a workaround or get some help from the seller if you just got it.