Help with amp fuse

Ceace

Member
2007-12-29 4:04 pm
I have had my amp and sub for 4 years. Some how my fuse and fuse holder got damaged, so I threw it away. The problem I have is that I need to know what capacity fuse do I need for my 900 watt amp? All of my papers that came with the amp are in a land fill somewhere. What is the best way to figure this out?
 
Is it 900 watts rms or 900 watts peak? If its rms, then you'll probably be ok with an 80 or 100 amp. If its peak, a 40 will do. If your amp comes with its own fuses, just go about 20 amps higher than the total fusing on the amplifier. Otherwise, if the amp has no built in fuses, you will need to refer back to sentence number two, above. :)
 

aznboi3644

Member
2007-12-15 3:00 am
ppia600 said:
Is it 900 watts rms or 900 watts peak? If its rms, then you'll probably be ok with an 80 or 100 amp. If its peak, a 40 will do. If your amp comes with its own fuses, just go about 20 amps higher than the total fusing on the amplifier. Otherwise, if the amp has no built in fuses, you will need to refer back to sentence number two, above. :)

Please don't post incorrect information. Your statement of fusing 20 amps higher than the amps total fuse rating is wrong


if you are talking about fusing the main power wire than that fuse has NOTHING to do with the amplifier(if the amp has built in fuses which 99 percent of amps do).

the fuse is to protect the wiring in case of the short.

NOTHING to do with the amp and its fuses

Just fuse the power wire accordingly depending on its size and length
 
aznboi3644 said:


Please don't post incorrect information. Your statement of fusing 20 amps higher than the amps total fuse rating is wrong


if you are talking about fusing the main power wire than that fuse has NOTHING to do with the amplifier(if the amp has built in fuses which 99 percent of amps do).

the fuse is to protect the wiring in case of the short.

NOTHING to do with the amp and its fuses

Just fuse the power wire accordingly depending on its size and length


Hey, I think you need to read again and think this time. While you are correct about the fuse at the battery end, I am correct in both of my statements. Maybe you should read again when you wake up, its a little late to be arguing with me about amp wiring. I can do this in my sleep.
I am telling him to use a rating at the battery end of 20 amps higher because most of the time the next fuse step at that level is 20 amps. I am aware of the purpose of the one at the battery and the point of having it only 20 amps higher than the ones on the amp is to allow only just enough current for the amp's operation. There is NO point in using a 150 amp fuse, for example, at the battery when the actual amplifier fuse rating is only a 40. Having a 0/1 gauge wire for example isn't going to make a 300 watt amp, for example, that is located ten feet away from the battery, for example, play any better than using a 4 gauge wire. There is NO point in using any fuse size larger than the amp's own fuses except by the smallest possible increment at the battery end.

For example:
30 amp fuse on amplifier ------- 40 or 50 under hood
40 amp fusing on amplifier ------ 60 under the hood
60 amp fusing on amp ------- 80 under hood

I'm saying this mainly because while you can theoretically use the same exact fuse rating under the hood that is on the amp, using a little higher rating under the hood (ONLY if the amp doesn't have built in fuses) gives an infantecimally less voltage drop under the hood and will protect the wiring quicker without popping the under hood fuse prematurely, in case of the tolerance of the underhood fuse being slightly off from the amp fusing. (several manufacturers of aftermarket fuses are crappy and can have inaccurate ampere ratings or poorly soldered internal ends which will be less evident if you pick a slightly thicker fuse to lessen heat buildup to an extent)
 
The only problem I see here is that nobody asked him what size power wire he had. If his amp has fuses on it, they are to protect the amp. The fuse under the hood is there to protect the car. Without knowing what size wire we are dealing with, we really can't answer that question.

Edit: I went back and re-read and I did see where Aznboi did mention that it depended on wire size. But if Ceace will let us know what size wire he has maybe we can help him.
 
I Am An Idiot said:
The only problem I see here is that nobody asked him what size power wire he had. If his amp has fuses on it, they are to protect the amp. The fuse under the hood is there to protect the car. Without knowing what size wire we are dealing with, we really can't answer that question.

Edit: I went back and re-read and I did see where Aznboi did mention that it depended on wire size. But if Ceace will let us know what size wire he has maybe we can help him.


My statements are based on Cease's original statement that his fuse holder was damaged so he threw it away. He never stated he changed wire size or the amp, only that he needed another fuse. So I was ASSuming his setup was working correctly with the wire size he had. There is the possibility it was professionally installed.
You can run a 2/0 power wire to a 150 watt amp, but that doesn't mean you use a 250 amp fuse under the hood. You only need a fuse rating slightly higher than the ones on the amp, if there are any on the amp, otherwise you use what rating the amp needs at the battery. Its simple really.

For example, my amp has no internal fuse, so I have to use the rating under the hood that the amp requires. Of course this is assuming I'm using the correct wire size in the first place. If I were running a small amp with a 30 on it, I'd use a 40 under the hood so I wouldn't have to raise the hood to change the fuse if the amp had a problem, because the 30 would go first.
 
You could actually use a 40 under the hood. That amp is rated at 300 watts rms bridged into a 4 ohm load and probably actually puts out about 375 to 400 rms bridged. You don't want to use an excessive fuse size when the amp doesn't have built in fusing. If there is a problem with the speaker or vehicle voltage issues, having too large of a fuse can cause more extensive damage to the amp.
 
ppia600 said:
You could actually use a 40 under the hood. That amp is rated at 300 watts rms bridged into a 4 ohm load and probably actually puts out about 375 to 400 rms bridged. You don't want to use an excessive fuse size when the amp doesn't have built in fusing. If there is a problem with the speaker or vehicle voltage issues, having too large of a fuse can cause more extensive damage to the amp.

^^^ Agreed but its demise could only lead to an upgrade/improvement , lOl.


:eek: :D :smash: ... Polo.
 

jol50

Member
2007-11-08 2:14 am
My 5ga kit came with a maxi fuse 100a. It seems ok so far. I used to use atc 30a on battery, or two. I used the covered outdoor holders because they corroded otherwise. I still had to pack the holder with dielectric grease and then they would hold up pretty well. That reminds me I should put some in this 100a. That stuff works great on lots of things like trailer plugs and ignition systems.