Just found out most residential panels are rated for way less than people think

I was reading through some old code updates from my local inspector in Cleveland and stumbled on something that made me stop. Apparently a standard 100 amp residential panel can only handle maybe 80 amps continuous load before you start running into thermal issues. That blew my mind because I have seen so many homeowners pack those things with breakers like it is a game of Tetris. The math works out to something like 19.2 kW max continuous on a 240 volt service. I even tested it on a house I rewired last month and the panel was hitting 150 degrees at the main lug after running the AC and oven at the same time. Has anyone else caught this or is it just me because I feel like I missed this in school?

2 comments

2 Comments

jana_fox501mo ago

That "80 amp continuous" thing really got me thinking.

evan_wilson181mo ago

It's one of those specs that sounds good on paper but gets weird in practice. 80 amps continuous means you're pulling nearly 10 kW nonstop, which is a serious load in any setup. Most people don't realize how much cooling and wiring that actually needs. Battery chemistry starts fighting you hard at those currents too.