I have two amps a xtant a3001 and a alpine mrv-f409. What amp fuse should I use? The guy at hifi buys told me to us a 150 amp fuse. What do you guys think.

 

is this the main fuse coming off the battery or the fuse in the amp, or the fuses in the distribution block.

 

is this the main fuse coming off the battery or the fuse in the amp, or the fuses in the distribution block.
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Exactly what I want to know. The fuse coming from the battery needs to be of a capacity to match the power wiring. The ones on the amps need to match up to their power needs/capacities.

 

OOPS sorry the main fuse from the battery

 

The wire gauge and length determines the proper fuse rating.

 

Sp how about 18 feet of 8 guage wire. what fuse should i use by the battery????????

 

that should be taken into consideration, but also ...

you take all the fuse ratings of all the amps/equipment you will be running off that wire and add them up. say it is 25, 35, 20 amp fuses that your amps use. that would mean you need an 80 amp fuse at the battery.

 

Nope, wrong answer. The fuse at the battery is installed to protect the power wire. Not the amps. The amps have their own fusing closer to their termionals. 16-19 feet of 8 gauge can only take 0-20 amps current. So I think you need heavier gauge cable for those amps. But you shouldn't need more than 12-15 feet of cable. 4 gauge 13-16 ft can take up to 65 amps before melting or causing appreciable voltage drop.

 

Correct me if I am wrong here, but doesn't the current in have to equal the current out? If the amps can take up to 20 amps each, then if you have 3 20 amp fuses at a distribution block, then don't you need at least a 60 amp fuse at the battery? You could have more than 60 amps, but wouldn't that be the minimum?

 

If you want your amps to receive the current they need to operate at full power you first must get wire capable of transferring the current. It does no good to install a 60 amp fuse if the wire will melt between 25 and 45 amps.