Fuse Size Question

[Shelbrain 10+ year member]

I am preparing to install an Alpine MRV-F345 4 channel amp:

http://iweb.alpine-usa.com/pls/admn/item_info?p_item_name=MRV-F345&p_category=40&p_subcategory=120&p_main=10

My concern is that the amp has 2 30 amp fuses on the amp itself. Does this mean I need to get a 60 amp fuse for this amp at the distribution block or alternatively, is the 2nd 30 amp fuse just a backup.

What size fuse do I need for the distribution block? Thanks!

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[forbidden 10+ year member]

You are fusing the lines capacity to carry current, not the amp. For example a 4 gauge line can be fused up to 120 amps even though the draw through it may only be 75. You want to ensure that the fuse is the right size for the wire and make sure the wire is the right size for the amp(s). I would think that a 4 gauge line is more than adequate for you.

 

[bimma85 5,000+ posts]

You are fusing the lines capacity to carry current, not the amp.

like he said you fuse the wire, not the amp. The amp already has fuses in it //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif. Search for fuse wire amps or fuse size wire etc. You'll find a link to a website with all the info you need.

 

[Shelbrain 10+ year member]

Well I am running 4 gauge wire into a distro block. At the battery, I have a 150 amp fuse. I am running 3 8 gauge wires off of the distro block. Each 8 gauge ranges froim 5-10 feet in length. The 4 channel amp is 300 watts. The sub amp is 300 watts for now (may be upgraded to 500). I am also running a 120 watt carputer.

What size fuses do I need for the distro block?

 

[knukonceptz 10+ year member]

The Main wire can be fused for its max rating at the battery at the duistribution block you would want a 60A fuse if that amp is powered by one "leg" of the block.

Also, nothing wrong with fusing the line for the current being used in that line instead of its max rating. Its better to be conservative as that fuse protects your car in case you are in an accident.

 

[Shelbrain 10+ year member]

So what size fuses are recommended? I purchased my fuses from Knuconceptz...looks like I will need another order once I figure what sizes are needed.

 

[knukonceptz 10+ year member]

Do you have just the one amp? If so a 60A in the distro block and a 60 - 120A in the inline fuse holder is fine.

 

[Shelbrain 10+ year member]

I have two amps and a 150 watt car pc

The 4 channel amp is 300 watt (75x4)=60 amp fuse

The sub amp is 350X1=??? size fuse

The 150 watt pc=30 amp fuse

 

[chibahawk 10+ year member]

my man i jus asked this exact question two threads down..

go with ONE 60A fuse for the 2 30A fuses.. they work together

 

[Shelbrain 10+ year member]

my man i jus asked this exact question two threads down..
go with ONE 60A fuse for the 2 30A fuses.. they work together

That's exactly what I need to know...thanks. Can you help me figure out what size I need for the sub amp? It is an Alpine MRD-M305. 350 watts

 

[chibahawk 10+ year member]

well if you've got the amp right now or the manual it should list what size fuse the amp currently has in it..

 

[Shelbrain 10+ year member]

It wasn't available at the time...40...so I will just get the same for the distro block