Fuse capacity

[CA-Noobie]

Hi all, I have a question about fuse capacity... planning on wiring up two Polk amps in my vehicle, one is the C400.4 4-channel amp which has 2x30A (60A total) fuses in it and the other is the C500.1 mono amp which has 2x25A (50A total) fuses in it.

My wiring plan is that I run a 4ga wire from the battery to the back of the car into a distribution block, then split out to two 8ga wires, one to each amp.

What size fuse do I need close to the battery?

Thanks in advance for any help you can provide.

[spwuinmk67]

Go with the total of the two amps...so around 110. You could also do a 100a fuse, be a little safer, but either should be fine.

[exalted512]

id put a 75A fuse.
-Cody

[MacLeod]

Id go with the combined as well. I wouldnt go over it any cause the 2 30 amp fuses and 2 25 amp fuses are well beyond anything those amps are ever gonna use. So Id go with 100-110.

[exalted512]

youre not going to draw over 75A over a long enough to blow a 75A fuse, but honestly, anything b/t 75A and 150A is great. At the bottom you have 75, which is just a little more than the max you will ever draw, and at the top is 150A, which is the amount of current 4awg can handle. ultimately, the fuse at your battery does NOT protect your amps. it protects your wire to the amps. so if you have more than 150A of current going through your wire your wire is going to be screwed.
So, just get whatevers cheapest that you can find anywhere from 75-150
-Cody

[ntculenuff]

i am a big fan of circuit breakers instead of fuses, you might look into one of those too:)

[CA-Noobie]

Thanks all for your thoughtful and insightful input and answers!

[LittleCar_w/12s]

Well, you have to keep in mind the real purpose of the fuse at the battery is to prevent a meltdown if the cable is cut on the vehicle frame somewhere.

Cody's right about the 150amp being the upper limit on the 4ga as a rule of thumb. It will blow before the wire melts. However the 75 is a bit cheaper sometimes.

In any case, if the wire is cut on the frame, either fuse will open. You are better getting the larger one, however, as it is meant to protect the wire (150a roughly max) not the equipment.

The fuses in the amps are meant to protect them, and need no extra protection. You don't want to be blowing a $5 fuse because of a musical crescendo. If the amp goes past it's own ratings, the local fuses will blow for 30c.

[PoweredByDodge]

actually - i've found that many amplifiers have too great a value of fuse onboard, which results in insufficient protection in case of inter-amplifier shorts or other havoc.

100 x 4 + 500 x 1 = 900 w / 14.4 = 62.5 Amps (roughly).

I would use an 80 Amp main fuse. Anything higher proves futile.

150A fuses can cause a lot of havoc before they blow -- you can arc-weld for a few seconds before the damn thing blows.