I'm building a robot for the kids next door, the whole thing runs off a 12V Lead acid battery. I'm just about to put in the circuit protection, and I was wondering if a home circuit breakers would be able to protect a 12V DC circuit?
My wiring is 15Amp, so I would be looking to put a 15Amp breaker in the main battery feed.
What do you think?
Dave
I think I would discuss it with a lawyer first. Oh, your neighbor is a lawyer?
Practically, yes.
Many home breakers also have a DC rating which is not often recognized. For example, the 10 - 70 amp Square D QO breakers are UL listed for use at 48 volts DC.
Many other breakers have similar DC ratings. Not many people know that.
I think you would be better off using an automotive-type 15 amp fuse. You can get the fuse-holders on pigtails at the auto stores, for cheap.
However, as to breakers - It depends on the design of the breaker, and there are several types of residential "breakers". A few are also rated as switches, since the common breakers are only rated for a certain number of "throws". (That info, just in case you are thinking your design will be tripping the breaker a lot, and you are ignoring the part about redesigning it because you are tripping breakers.)
Some fusing devices rely to some extent on the AC passing through zero volts to help quench the arc that occurs whenever there is a fault. DC current devices need to break the full-amp arc.
The breaker you want, if you don't use the inexpensive auto fuse, should have a rating for AC and a rating for DC. Just use one that has a 15 amp DC rating.
I would be very careful. Circuit breakers on ac work because current is limited by transformer reactance. The breaker finally breaks the circuit at a current zero crossing. A typical auto battery can supply hundreds of amperes into a short and will produce an arc that may be difficult to extinguish.
Have you ever looked at what happens inside a solenoid switch used for auto starters? It is not a pretty picture.
Bill
-- Fermez le Bush--about two years to go.
Don't screw around with a home circuit breaker - too big (physically) & too hard to mount & connect. Buy a nice panel mounted breaker - easy to install and easy to make the connections. DigiKey # 432-1056-ND $2.08.
Ed
i would use an automotive type breaker. they should be available at most any auto parts store.
auto type fuses and holders are low cost and easy to install on each individual motor or light. you can pit a small indicator across each one so it lights if/when the fuse blows.
Are you asking this because you just happen to have one laying around? I ask because it would make MUCH more sense to just put in a small inline fuse and holder you got from Radio Shack.
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