Surprised by how many lights I could run on a single 15 amp circuit after actually doing the math

I was wiring up a new workshop space in my basement over in Arlington, and I wanted to put in about 12 LED shop lights. I figured I would need two circuits minimum, just to be safe. Then I sat down and actually did the load calculation. Each light only draws 0.5 amps, so 12 of them is just 6 amps total. That left me with plenty of room for a few outlets on the same circuit too. I double checked the box capacity and wire sizing and it all worked out fine. It surprised me because I always heard old-timers say not to load a circuit past 80%, but that still leaves 12 amps available. Has anyone else realized they were overthinking their lighting layouts because they assumed lights pull way more than they actually do?

2 comments

2 Comments

black.patricia5h ago

Yeah my buddy did the same thing in his garage and then realized he could plug a space heater into the same circuit and trip it instantly... funny how fast that 80% rule goes out the window.

logan_dixon184h ago

Oh the 80% rule is more of a guideline for continuous loads, not a hard limit for circuit breakers lol. A tripping breaker is actually doing its job with that space heater, the 80% thing is about what you should plan for not what the breaker can handle.