Fuse ratings
 

Ive just installed my system (grinning from ear to ear), the wiring kit i bought has a 120a fuse in it. My system only needs two 50a fuses in (ran two power wires until i can get a power distribution boc).

Because its a safety net, i think i should probably change it to a 60a fuse or something like that?


Thinking about it can someone give me a hand working out the fuse rating that i need?
This is what my amp is:
# Dynamic Power: 400W
# RMS Power (2 0hm): 200W X 2
# RMS Power (4 Ohm): 100W X 2
# Bridged Power (4 Ohm): 520W X 1

RMS / 12 / 0.75 = Fuse amp rating (correct?)

How have you wired the amp?

Worst case is bridged, 520W (assumin that's rms) which if the amp was 100% efficient, would draw 520W/12V = 43Amps ish with a sine wave signal.

The amp wouldn't be that efficient, 80% may be a good guess in the absence of info.

This means it could draw 43/0.8 = 54A worst case (sine wave etc.).

You'd therefore be fine with a 60A fuse.

The fuse is only there to protect the wiring, or rather to stop a short buring the cable out and your car too possibly.

If the wire in the cable kit can take 120A (suggested by the fuse supplied) then it should be up for 60A easily.

How have you wired the two power feeds; are they just in parrallel?

Whatever, 60A 'should' be fine.

Especially as you're unlikely to be running a pure sine wave signal at full power (unless you're doing SPL competitions etc); music roughly takes between 25% and 75% power compared to sine waves, so the actual current will be less than the 54A mentioned above.

Hi,

Ahh ok i see, the rating is dependant on how its setup.

The wiring is parallel, the amps and the wiring is rated for 120a, but the worst case draw, as you say is 54a.

Ive got a 120a fuse at the moment, so should be fine for quite a bit. Do you recommend me dropping that down at all? Or just leave it?

If the cable is rated for 120A then there's not much point reducing the fuse imho. :D