Amp fuse sizes?

[Mass Car Audio 10+ year member]

I can't believe how dumb people can be and keep arguing about this, just listen to NASTY08IMPALA.

YOU FUSE FOR THE SIZE OF WIRE !!!!!!!!!

Way to many people think they know car audio when they actually have no idea what the hell they are talking about..LOL

 

[fasfocus00 5,000+ posts]

How many of you noobs giving advice actually get paid to install? Received any training or did their own research? Nasty and I are right, do your research. When fusing off of a direct power source you fuse for the wire rating, after that fuse if there is fused distribution than you fuse per each units draw. Either way he can't fuse per amp bc the OP's amp kit doesn't have fused distribution. If he does have fused distribution right before the amps than the OP should read the owners manual of his amps to see what size fuse should be used.

 

[Roland 10+ year member]

How many of you noobs giving advice actually get paid to install?Received any training or did their own research? Nasty and I are right. do your research. When fusing off of a direct power source you fuse for the wire rating, after that fuse if there is fused distribution than you fuse per each units draw. Either way he can't fuse per amp bc the OP's amp kit doesn't have fused distribution. If he does have fused distribution right before the amps than the OP should read the owners manual of his amps to see what size fuse should be used.

The Installs i did where regulated by the FAA. The installs required me having a licence. That licence required 18 months of full time schooling. The installs also required an FAA licensed inspector to sign off on it. Sometimes installs had to approved by engineers before they even got started...

Dude, I'm not saying you're wrong, i'm just saying there might be a better way. There is A LOT i don't know about car audio, and i enjoy learning the stuff shared here. But there is one thing I have learned as a mechanic for over 30 years. Just because you have always done something one way or another, doesn't mean there is not a better way to do it.

I'm here to learn so, Can you tell me one reason why using a smaller fuse is bad?

 

[fasfocus00 5,000+ posts]

The Installs i did where regulated by the FAA. The installs required me having a licence. That licence required 18 months of full time schooling. The installs also required an FAA licensed inspector to sign off on it. Sometimes installs had to approved by engineers before they even got started...
Dude, I'm not saying you're wrong, i'm just saying there might be a better way. There is A LOT i don't know about car audio, and i enjoy learning the stuff shared here. But there is one thing I have learned as a mechanic for over 30 years. Just because you have always done something one way or another, doesn't mean there is not a better way to do it.

I'm here to learn so, Can you tell me one reason why using a smaller fuse is bad?

From your schooling you should be able to concede that me and nasty are correct. You should also be able to realize that you fuse for the wire off the power source for the wires rating than fuse for each component at a distribution block which the OP does not have. Fusing too small can cause unwanted resistance causing the fuse holder to melt than defeating the purpose of having fuses in the first place. This unwanted resistance can also cause heat issues in the wire itself. OP needs to get a fused distribution block and fuse at the distribution block per the owners manual.

Seriously FAA, you guys almost never use 0 gauge. You barely use 4 gauge. How many times have you put a 5 amp fuse on a 10 gauge wire for controls? Never. I install at a shop and see people use smaller fuses that try to repeatedly draw more current than the fuse is rated for causing the wire to burn or the fuse holder to melt causing more damage than using the correctly sized $1 fuse.

 

[Roland 10+ year member]

From your schooling you should be able to concede that me and nasty are correct. You should also be able to realize that you fuse for the wire off the power source for the wires rating than fuse for each component at a distribution block which the OP does not have. Fusing too small can cause unwanted resistance causing the fuse holder to melt than defeating the purpose of having fuses in the first place. This unwanted resistance can also cause heat issues in the wire itself. OP needs to get a fused distribution block and fuse at the distribution block per the owners manual.
Seriously FAA, you guys almost never use 0 gauge. You barely use 4 gauge. How many times have you put a 5 amp fuse on a 10 gauge wire for controls? Never. I install at a shop and see people use smaller fuses that try to repeatedly draw more current than the fuse is rated for causing the wire to burn or the fuse holder to melt causing more damage than using the correctly sized $1 fuse.

Thank you.

"Fusing too small can cause unwanted resistance causing the fuse holder to melt than defeating the purpose of having fuses in the first place."

I think this is were the confusion comes in. I can't for the life of me see how this statement can possibly be true. (but if that is your experience...) I guess we will just have to disagree on this.

I have only repeatedly seen the exact opposite. I've seen and repaired many melted wires ... but only when a fuses that was to big was used, or no fuse at all. The only way i know that you will melt a fuse holder is if you put in a fuse that is higher (a bigger fuse) than the holders rating.

Putting in a smaller fuse dose not increase resistance of the circuit in any real way. A fuse can cause a voltage drop as it heats up it a very small drop (like 0.1 volts) until right before it blows.

Quote Wiki

"In electronics and electrical engineering, a fuse is a type of low resistance resistor that acts as a sacrificial device to provide overcurrent protection, of either the load or source circuit."

Putting a smaller fuse will always protect better. In a electrical system a inline fuse not only protect the wire, and everything else down stream of the fuse. But it can also protect the system up stream of it also.

Lets say the stock alternator that OP still has in his car is still running his stock 12 gauge wire. He has a short down stream of the fuse. Which is going to burn out faster, the 12 gauge wire, or the 300 amp fuse? So if he uses a 100 amp fuse, not only would that protect his 0ga wire it also protects his 12 ga wire and ...