What you say is MOSTLY true but there are some significant caveats. Firstly, there is a big difference between AC overcurrent protection devices and DC ones. This is mainly because AC current goes to zero 100 ot 120 times per second, so arcs can be extinguished more easily. Almost all AC-rated current interrupting devices (switches, relays, fuses, circuit breakers, etc.) either are not rated for DC operation or have a significantly lower set of ratings for DC. Another reason for this is that DC circuits can have unlimited inductance without it placing an inherent limit on the current flow. With AC circuits, for a given voltage and current, there will be a maximum circuit inductance. Higher inductance makes arcs harder to stop. Household circuit breakers will work for DC, but they will have different characteristics and they will have a much lower maximum voltage and lower maximum fault interrupting current (this is NOT the trip current bur rather the measure of how high the fault current can be before the CB can no longer stop the arc that happens when it opens). All of this is likely irrelevant for the original poster's application since the available fault current is low. However, when you get into the realm of lead acid batteries of more than 5 Amp-Hours capacity, it can make a big difference. I just wanted to post a warning to people that they need to be careful in selecting overcurrent protection devices for DC circuits where the short-circuit current can be 100s of amps or more. Many AC fuses, switches, relays, and CBs will just arc over and destroy themselves, maybe causing a fire, in such an application. I have seen this first hand several times with 48V, 28 Amp Hour lead acid battery systems. Sean On Sun, Nov 24, 2013 at 7:44 PM, pic wrote: > Normal house fuses/breakers will pop at the rated current, voltage is > immaterial so you could just use that > In the UK lighting circuits are normally fused at 6 Amps, so depending o= n > the psu being able to supply the current to trip it this will work fine > (use a 12 V lead acid battery) > > > Years ago I replaced all the car fuses on a Citroen CX with domestic > resettable breakers (designed for 240V) including fitting a 100 amp unit > for the alternator output, > It all worked faultlessly for over ten years, no changing fuses, just > occasionally flip a breaker on again > > PC > > -----Original Message----- > From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf > Of > Carl Denk > Sent: 24 November 2013 22:31 > To: Microcontroller discussion list - Public. > Subject: Re: [EE] Low current breaker > > My heating contractor talks of a "Popper". As far as I can deduce, it's a > breaker in the form of a blade fuse like automotive. Probably in the > 2-3 amp ratings. > > What about when the circuit opens, a relay drops out, normal closed conta= ct > closes, triggers a 555 timer with a sonalert buzzer, and an LED strobe. O= r > program a small PIC to do the work. :) > > > On 11/24/13 5:08 PM, Charles Craft wrote: > > My son is working on battery powered circuits in school. > > Near the end they will wire up a model of a small house. > > We would like to add a breaker inline so that he can short two wires an= d > show the breaker tripping. > > Its doable with a low current fuse but having the sound and reset abili= ty > of a breaker would more closely match a real house. > > If everyone is watching they might see the flash of the fuse but then > that's more pieces for him to track. > > > > Thoughts? > > > > thanks > > chuckc > > > > > > > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change > your membership options at http://mailman.mit.edu/mailman/listinfo/piclis= t > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .