Outer Limits 4x4 Board

just wanting to know how hot fuse holders get when driving lights are on,

i can just hold my hand on mine for bit before it gets to hot,

Hi bucket, that sounds like it the wrong size fuse. Over heat a fuse will cause a voltage drop because of the resistance that is created as the fuse heats

If you are using glass fuses, I strongly recommend you replace them with blade fuses. Glass fuses are susceptible to a range of problems including getting so hot the cause the fuse holder to melt.

If you are using blade fuses, you can use a fuse size that is borderline for the amount of current it can handle before the fuse blows. The problem is that in this sort of situation, the fuse itself can melt and cause all manor of problems.

It is always good practice to design the circuit to be able to use a fuse about 25 to 50% larger that the maximum current intended to be handled by the circuit.

By the way, don’t just fit a larger current rated fuse unless you know the circuit, particularly the cable, can safely handle the high current that would be required to blow the fuse before any damage occurred elsewhere in the circuit.

Cheers.

What size fuse are you running, what cable, and what lights?

i'm running narva 100watt x2, big wire and 30amp fuse,

Hi again bucket, if your running a 30 amp fuse and it’s getting that hot, you have a problem. Even running 2 x 100w = 16 amps, you should not have a hot fuse.

Time to check all the circuit for some form of problem.

As chimpboy posted, what size cable are you using.

You must be running insufficient cabling, or accidentally running the power through the relay triggering wires, or maybe you have a really bad connection near the fuse panel or something.

You are right to think there's something wrong... I agree with Drivesafe, it shouldn't be getting more than slightly warm at the fuse or along the cable.

Stupid question but is it definitely the fuse causing the heat, not some other nearby heat source?

na, its defintly the fuse, i can hold the wire going in and the wire coming out, but its mainly the fuse holder, its the black type that screws together,

Hmm, some of those fuse holders are absolute junk and have far too little metal conducting all the current.

If it is the kind that has a separate "in" for every "out", you could try running the power across two 15A fuses instead of one 30A.

If it's the kind where there's one big "in" for all the "outs", there's not much I can suggest. You could grab a big inline fuse holder from jaycar or something and see if that fixes the problem, they come with cable sticking out of each end. Not my favorite style but possibly suitable for you.

Like this (cut the wire in the middle to use):



I used to use this type:



but personally prefer this type now it's available:



What have you got?

Jason

the same as the first one, with the pink wire, but mine is yellow wire,

bucketofbolts wrote:the same as the first one, with the pink wire, but mine is yellow wire,

That’s a glass fuse type and the worst type of fuse and fuse holder to use for high current automotive use and heating like what you are experiencing is common place with glass type fuse holders.

What you can do to try to temporarily fix the problem, is to open fuse holder and clean the ends of the fuse and clean the contacts on the ends of the wire.

Also stretch the spring in the fuse holder to make a tighter contact between the wire contacts and the ends of the fuse.

As posted above, I would strongly recommend that you replace the glass fuse holder with a standard in-line blade fuse holder.

Cheers.

whats the best ones to get to handle high current

Hi Paul, for switching things on and off, use relays.

Always use decent size cable and in your case, swop the glass fuse for a blade fuse.

Cheers.

bucketofbolts wrote:whats the best ones to get to handle high current

If your vehicle already uses blade fuses in its fusebox, then go with them (similar to pic 2 and pic 3). Mount the new fusebox close to the battery so you can use the extra fuses for other purposes (fridge run to back of vehicle?) and fill the new fuse box with fuses of different capacities (good location to carry spares, don't get lost...).