Can I use normal AC circuit breaker for DC current?

Flashlight Modding and DIY Parts
1

This has been on my mind for some time - can we use the standard AC circuit breaker to set the tripping max current for DC power supply?

The very reason is obvious, it’s available everywhere, it’s easy to build, easy replacement, it’s budget, and tons of current selection. The best thing is that it is reusable, if you shorted your DC, it trips, you find the fault - fix and reset… easy.

And did I mention a good 8-output rail housing only cost around $3?

So, would it work? I read aroudn, seem like it should work, provided that you use at 1/5th the voltage, that’s an easy peasy requirement since I intent to use this for 5v and 12v only. But I would like to gather some more input from more experienced users here before I start.

2

I read that a good start is to use it at 1/10 of the rated voltage, same amperage.

e.g.: 120VAC 15A becomes 12VDC 15A.

YMMV.

3

Got it. Well, good thing everything here is rated 250VAC so 1/10th that would still be 25VDC… twice of my 12V requirement :slight_smile: … looking good so far.

4

It will ‘mostly’ work. Do keep in mind, however, that circuit breakers are usually quite slow to respond. They rarely save anything from being destroyed.

PPtk

5

Thanks, I’ll keep that in mind. Just curious though, how slow are we talking about? By saving “anything”, you do mean the small circuits etc, right? To be honest, I’m not as much concerned on saving project stuff, but more concerned of the wires catching on fire - or worse.

Let’s say, theoretically, the PS capable of supplying 12V, 14A = 168W, is shorted. 14gauge wire, 10meter. The circuit is linked in series with AC 6A breaker. How slow would you say it will trip… would it still be fast enough to prevent any heat buildup on the wiring?

6

Oh, Yeah. It will save the wiring. 10 Meters of 14 Guage, in fact, could survive 14A dead shorted into it for quite a while.

The breaker will pop in < 1 Second. An ETERNITY for sensitive electronics components, but PLENTY fast to save your wiring.

PPtk