Fuse housing melting but fuse not blowing, ppi amp

[luka]

Hi

It should even get warm, my doesn't!!

[rawadia]

I agree, it shouldn't. Also the cutting in and out, occured at very low volume, if that helps any.

Just to get some knowledge thrown at me, I'll present a hypothetical situation:

If an amp was shorting out, due to internal short or output wiring, would a large enough amount of current flow in the power wires , after or whilst the protection circuitry is cutting the amp on and off?

[Perry Babin]

The problem is resistance. There's too much resistance at the fuse holder. When you draw current through a resistive point in a circuit, the point will heat up. High current will cause significant heating. If all of the components (fuse, holder, connection to wire...) were good quality, excessive current would simply blow the fuse.

You need to use a different type of fuse holder and/or a better quality fuse (only Bussmann or Littelfuse for this type of fuse). If you must use this type of fuse, use a high quality, open fuse holder. Gold plating doesn't make it high quality. Buy one from a high-end manufacturer. Maxi-fuses and ANL fuses have fewer problems.

ppia600 has a lot of experience with installation problems/solutions. You should take his advice.

The amp starts to cut out because the fuse holder begins to heat up, the connection deteriorates and the voltage at the amp begins to drop (due to increased resistance at the fuse holder). The deterioration is cumulative (any tiny resistance will soon become significantly more as you draw current through it).

[rawadia]

Very good. I'll upgrade the fuse.
Now for running wire and fuse size, what are y'all's suggestions for that? Is the 8 gauge sufficient for the dist of the distribution block to the amp? If I did run the 4 gauge all the way to the amp, how can I connect it? 4 gauge won't fit in the connector.
thanks, appreciate all the input from everyone.

[Perry Babin]

If a 60 amp fuse doesn't blow, the 8g may be enough. If the 60 amp fuse blows, you need larger wire.

After you get a good quality fuse/holder, check the temperature of the wire after running the amp at high volume for a while. If the wire doesn't feel warm (relative to the ambient temperature), it's OK. If the wire feels warm, it's too small and you should go to the next size.

You can buy 6g wire. People rarely use it because it's not readily available at car audio shops. You can get it from an automotive or welding supply house.

[Eva]

I have seen that happen too. That kind of Chinese fuse holders tend to make poor contact with the fuse at both ends, as if they were sized to accomodate a slightly bigger one. Try narrowing the ends a bit so that the fuse becomes firlmy clamped. This should be more than enough for a 4x100 amplifier. You can even try 30A and it will hardly blow either.

I have also seen low quality Chinese fuses that either come completely open from the factory, or they have weak solder joints at both ends and become open later without the internal fuse element actually fusing (they are easily repaired by drilling a small hole at each end and soldering back the fuse element... It's a pity to throw away a brand new fuse...)

[jol50]

Back in the day about all I could find was the flat auto fuses at 30A. They would heat a little (could barely feel it at full output) but then they or the holders would corrode and turn into a problem area. They would cut out and melt even though they were not getting hot from current; they got hot after they developed a bad connection. I finally figured out to fill a new one with dielectric grease and put a new fuse in it, never had problems with them after that. They were under hood in a dry area behind the battery, also had that issue in trunk. May not help other types of holders, but a little heat seems to exploit any weakness in a fuse holder not bolted together. I assume without air the metal can not oxidize so easily.

[luka]

Hi

Why do you use so small fuses? You don't protect the amp, you protect cable and that's it!

[richie00boy]

Are these bigger version of 20mm fuses that bad? My system has a 20A fuse and is just a 4x75 and 1x300 amp. Should I be dumping the fuse setup for ANL? I had a look and ANL fuse holders are £25 or £12 for cheap gold tacky looking ones. Not sure on the wire gauge but the outside diameter is no more than 10mm I would say, quite likely upto 2mm less.

[I Am An Idiot]

The smaller (in current rating) fuses are fine. You will not have near enough heat produced on a 20 amp fuse to have this problem.