How big a fuse to get?

[savar]

I recently got a RF T400-2 amplifier and a single 12" to match. This is my first time installing an amp & sub so I've been reading up on it online.

I thought I had all the pieces I needed until this morning at work it occurred to me I hadn't bought the fuse yet.

So I went to Circuit city after work and got a fuse holder. The owner's manual for my amp recommends a 100A fuse on the power wire, but this doesn't make any sense to me, because the amp is spec'ed at 400W RMS. So at 14V, the average current when the amp is cranking would be about 30 amps. Even at 1000W peak, the amp is still only pulling about 70 amps.

The point of this rambling is that Circuit City didn't have 100A fuses, so I bought a pack of 80A fuses instead. Will this work? Maybe I don't understand the point of the fuse, but I figure this fuse will blow if there's a short between the fuse and the amp, but there's enough headroom that it won't blow during normal operation of the amplifier.

Am I right?

If it makes a difference, I'm running a 4 AWG power wire from the battery to the trunk in a 97 Integra.

Also, the fuse holder has little screw holes on it like it should be mounted -- is that necessary? I only put about 8" of cable between the lug and the fuse holder. That's not much room to work with if I need to mount the fuse holder.

Edit: 3rd question...my head unit has one remote turn-on lead, but I have a power antenna and an amp. Can I splice both the antenna lead and the amp remote turn on into the same lead from the head unit? The manual says 300ma max for remote turn on...I have no idea how much each one uses but I can't imagine its more than a few ma each, right?

Thanks--

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[spoonraker 10+ year member]

Yes, fuses are designed to blow in case of a short, but not during normal operation.

Fuse holders have holes so you can mount them a lot of the time, but you don't need to mount them. I don't ever know why you wouldn't, it looks nicer, and stops it from rattling around. Technically speaking, you don't need to mount them.

You can split your remote wire as many times as you need. I'm running two amps, a CarPC, and a relay for some LEDs off of a single wire, works fine. I've heard of people running a bunch of amps having problems, if you find that is the case, it's an easy fix, just use a more powerful constant 12v source and use the remote wire to trigger a single relay.

 

[CrazedCat 10+ year member]

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[pzaully 10+ year member]

Yes, fuses are designed to blow in case of a short, but not during normal operation.
Fuse holders have holes so you can mount them a lot of the time, but you don't need to mount them. I don't ever know why you wouldn't, it looks nicer, and stops it from rattling around. Technically speaking, you don't need to mount them.

You can split your remote wire as many times as you need. I'm running two amps, a CarPC, and a relay for some LEDs off of a single wire, works fine. I've heard of people running a bunch of amps having problems, if you find that is the case, it's an easy fix, just use a more powerful constant 12v source and use the remote wire to trigger a single relay.

Great advice. I use the antennae and the remote power from my HU to power my amplifiers and that seems to work well. Pretty much any relayed 12v that kicks in when the cars ignition is set to running will work.

My ANL fuse case isnt mounted, but it is zip tied (wire tied some call it) near the battery because the closest bolt/screw mounting position was too close to where the power wire goes through a rubber grommet in the firewall.

Pzaully