Circuit Breakers vs Fuses

[nlouthan]

It seems that almost every stereo install here uses fuses at the amplifiers instead of circuit breakers.  Is there any specific reason why this is preferred?  What are the advantages or disadvantages of either setup?

Edited April 9, 2017 by nlouthan

[Bawshogg]

Fuses typically interrupt faster than breakers. They are cheaper for one , and you shouldn't have issues in a boat that cause multiple "resets" of a breaker. It's just not necessary in most installs. 

[Slurpee]

I used a circuit breaker. 200A stinger job I believe.  I have a reason though.  I hate hunting for the freaking fuse and replacing it in the middle of the lake or going without until I can find a replacement fuse.  It's not a big deal.  I've had to do it only 3-4 times in 16 years, but it's a pain.  And the most likely faults you want to protect against are from wiring or gross shorts which is exactly what circuit breakers are meant for.  We protect our home wiring with them for instance.  You can also use them as a disconnect switch for the amp board. My favorite feature.

First, a circuit breaker and fuse are vastly different devices that do the same thing.  Fuses are fast acting and typically great for electronics that have no native protections and will be subject to unknown loads being attached - like amplifiers.  They're not so good for devices that need a surge of current at one time.  For instance motors need a surge to get started.  So Circuit Breakers forgive that initial surge unless it goes on too long.

Fuses are inexpensive, react quickly and then need to be replaced.  Tools.  Where do we keep those fuses?  Anyone remember?

Circuit Breakers react more slowly relatively speaking and then can be reset.  It's not an infinite reset device though.  Every trip of the breaker takes a little of its life away.  But in a good cleanly installed Audio system you're not going to expect a lot of resets.  Also, circuit breakers don't like really rough handling.  Too much vibration and abuse and they might open for a short nuisance period or open as a false break requiring a reset.  I mean ROUGH vibrations.  Not what we get on boats normally.  And a circuit breaker may not like the marine environment because of corrosion potential - choose carefully.

So all things being equal what are you really preventing with an over current protection device in a mobile audio system?  Modern amplifiers protect themselves electronically and sometimes add their own onboard fuses.  So what then?  The answer is your are protecting the rest of the boat - mainly the batteries - from an over-current condition which is typically a short circuit.  Too much juice into a short from the batteries will cause a bad situation. Maybe a fire.  The most likely causes are water/contamination bridging the 12V to GND.  Mechanical causes like wires coming loose and contacting.  And good old electronics failures such as the power stage giving up the ghost; which means the electronic device in question is already a write off.

There's nothing wrong with either approach.  I think a high quality circuit breakers make the most sense for me.  Others will have a different perspective or course.  My previous install put both in series.  The fuse was pretty big and wouldn't open unless something really went wrong AND the circuit breaker failed and stayed closed.  I wasn't that paranoid this time after it never happening after 11 years in that boat.  But now you know and can make your own decision.

[MLA]

In a marine install, there are locations where a sealed,waterproof ignition protected marine breaker is better than a car audio fuse holder.

[Nitrousbird]

I went with fuses (on the amp board side) simply due to cost.  I've yet to blow a fuse so the ease of use a circuit breaker has doesn't really apply for my use case.  I use the factory breakers for other stuff that have popped (and would have been ticked if they were on a fuse).  I will probably look at breakers on the next boat/build I do, as I will go with a bigger system and have a few more bucks into it.

[nlouthan]

Thanks everyone for the guidance.