Thread: Fuses Vs Circuit Breakers

The other thing you should be looking at is the IP rating of the breaker.
[ame="http://en.wikipedia.org/wiki/IP_Code"]IP Code - Wikipedia, the free encyclopedia[/ame]
Inside a Landrover may be a dusty and/or damp environment. You may have to install these breakers in a suitable enclosure.
They can fill with dust and moisture and corrode internally. That could cause them to fail to trip when there is a fault, the cable heats up, bursts into flames and you're left with a charred mess. I've seen the results of protection failure on all sorts of cars and other assets.

Both circuit breakers and fuses have one thing in common, they sit there quietly doing nothing until something goes wrong. They then act to isolate the faulty circuit before major damage can be done to the fused equipment or the cars wiring. This may sound a bit simplistic but it is what they do. Why would you want to replace inexpensive fuses with circuit breakers that cost tens of times the cost of fuses ? It might be more convenient to reset a circuit breaker but a better option is to fix the fault causing the overload.
One way to avoid the multiple blown fuse scenario is to carry a large wattage, say 50 watt, globe soldered across the end connectors of a blown fuse. When placed in the faulty circuit instead of a fuse it allows current to flow but glows brightly when overloaded allowing circuit operation and fault isolation without blowing a sucession of new fuses. Sort of a wiggle wires whilst looking for bright light method of fault finding.
DC circuit breakers are generally fast acting and not suitable for high start up current applications wheras fuses can be easily and cheaply made with 'delay' built in. If your fuse wire is straight it is a normal relatively fast acting fuse. If it has a small 'blob' in the middle of the fuse wire, a zig zag type conductor or is filled with fine sand it is a slow acting fuse. Not normally specified for auto use but cheap and effective. More usually found in the M205 type (short skinny) glass fuses than the 3AG (long fat) ones.
As for a single 40 amp fuse feeding driving lights, this equates to 500 watts of power !!! If you've got this much lighting on the front of your vehicle it might be better to run several circuits of lesser current to avoid voltage drop issues and to aid in fault isolation.

Deano

Originally Posted by Yorkshire_Jon

.................................Ive been over many badly corrugated roads in the Defender (Canning Stock Route, Anne Beadell,Oodnadatta to name a few) and have never had a circuit breaker drop out ...................................

Anne Beadell Highway East of Emu.
The corrugations here are about 500mm apart and half as deep as a beer can for about 100 Km.

If circuit breakers don't drop out here due to vibration they never will !!

Deano

G'day Folks

Aah! I thought that I recognised those part No's, they are Narva jobbies, available is both automatic reset and manual reset, should be available from the usual suspects, Repco,Bursons,Supercrud, etc Narva in the 556 +and 557+ range of part numbers, current cattle dog

They also do the standard type of 2 bolt mounting,2 post jobbies, in both manual reset and auto reset


cheers

I have a list of Murphy's Laws. One of his laws is; "A $300 picture tube will protect a 50 cent fuse"

Dave.

Folks you are over complicating an otherwise simple choir.

If a fuse keeps blowing, the correct procedure is to find the problem, not replace the fuse with a circuit breaker.

By replacing the fuse with an easily reset circuit breaker, you may actually be increasing the potential of damage being caused.

As posted by DeanoH and others, why replace a cheap means of protection with a much dearer one, that is designed to do no more than what the cheap device was designed to do.

One point of correcting DeanoH, while you are correct in that there are DC circuit breakers that operate quicker than a fuse, these types of DC circuit breakers are usually job specific, like designed to protect a sound system.

All AUTOMOTIVE grade circuit breakers operate in almost the exact same way a blade fuse works and as such can be used as direct replacements, but as above, why would you.

Again, if you keep blowing fuses, no matter how hard it is to find the problem, find it and fix it because the fuse only blows in an overload situation and by the time the fuse has blown, you may already be doing damage and each time the fuse blows, the damage may be getting worse.

Replacing the fuse with a circuit breaker, will only exacerbate the problem because you can have power back in the circuit quick which could mean the circuit, at the point where the problem is occurring, has not had time to cool down.

Yup! there is no substitute for "Trace and Repair"

Originally Posted by UncleHo

Yup! there is no substitute for "Trace and Repair"

Remove works

Martyn