multiple amps 1 fuse?

[pitbull239]

hey guys.. is it safe to run multiple amps off 1 fuse and use a distribution block?

[skittlesRgood]

not really. you should have a fuse wherever the wire size changes. if you have 1/0 with a 300amp fuse then split it into two 4awg wires and one 4awg wire shorts, the 4awg will melt and burn before that 300amp fuse blows.

[pitbull239]

not really. you should have a fuse wherever the wire size changes. if you have 1/0 with a 300amp fuse then split it into two 4awg wires and one 4awg wire shorts, the 4awg will melt and burn before that 300amp fuse blows.

thanks for replying. yeah i under stand that but im not changing wire size. i had planned on running 4 awg from the battery terminal down to the fuse and then on the other end of the fuse continue with 4 awg and then put a distribution block. then run 4 awg to the other amps from the block. is this ok? or no?

[skittlesRgood]

not really. you should have a fuse wherever the wire size changes. if you have 1/0 with a 300amp fuse then split it into two 4awg wires and one 4awg wire shorts, the 4awg will melt and burn before that 300amp fuse blows.

thanks for replying. yeah i under stand that but im not changing wire size. i had planned on running 4 awg from the battery terminal down to the fuse and then on the other end of the fuse continue with 4 awg and then put a distribution block. then run 4 awg to the other amps from the block. is this ok? or no?

eh, you can do that. its a bit of a waste but if you already have the wire, go for it.

[TheyDontWantMusic]

not really. you should have a fuse wherever the wire size changes. if you have 1/0 with a 300amp fuse then split it into two 4awg wires and one 4awg wire shorts, the 4awg will melt and burn before that 300amp fuse blows.

it really won't.

I have no idea why people think a 20mm^ cable will MELT before a fuse that has about 6mm^ of cross-sectional area.

[skittlesRgood]

not really. you should have a fuse wherever the wire size changes. if you have 1/0 with a 300amp fuse then split it into two 4awg wires and one 4awg wire shorts, the 4awg will melt and burn before that 300amp fuse blows.

it really won't.

I have no idea why people think a 20mm^ cable will MELT before a fuse that has about 6mm^ of cross-sectional area.

a fuse made to take 300amps vs a wire that can take 125amps IF its full spec OFC. what do you think will fail first? ive seen 1/0 melt before and the 350amp fuse was just fine.

[audiofanaticz]

^^^^^ yea

a ofc wire will take a bit of heat before melting. You ever thrown coper wire in a fire to see the purdy colors, only to realize 10 fires later that copper wire is still in tact? same thing concept.

Even if is CCA (copper clad aluminum) the melting temp of most aluminum is in the 800-1200 degree f range (depending of the alloy being melted). Sepereate wire strands may melt quicker when they are by themselfs, but twisted tightly like power cable, it takes a lot of heat...

However Im mostly 100% certain that skittles meant that the wires casing will melt(not the physical wire itself), just poor communication on his part.

and it is common sense not to fuse 4gauge wire at 300 amps, its asking for problems no matter how you look at it. Skittles knows his shit and gives trustworthy advice and answers.

[TheyDontWantMusic]

a fuse made to take 300amps vs a wire that can take 125amps IF its full spec OFC. what do you think will fail first? ive seen 1/0 melt before and the 350amp fuse was just fine.

the fuse of course, it would be stupid to think a 20mm^ cable will melt before a 6mm^ fuse.

[skittlesRgood]

^^^^^ yea

a ofc wire will take a bit of heat before melting. You ever thrown coper wire in a fire to see the purdy colors, only to realize 10 fires later that copper wire is still in tact? same thing concept.

Even if is CCA (copper clad aluminum) the melting temp of most aluminum is in the 800-1200 degree f range (depending of the alloy being melted). Sepereate wire strands may melt quicker when they are by themselfs, but twisted tightly like power cable, it takes a lot of heat...

However Im mostly 100% certain that skittles meant that the wires casing will melt(not the physical wire itself), just poor communication on his part.

and it is common sense not to fuse 4gauge wire at 300 amps, its asking for problems no matter how you look at it. Skittles knows his shit and gives trustworthy advice and answers.

that is what i meant. thank you. the copper melting isnt the thing to be worried about. its the heat that is allowed to build up in the smaller wire that can cause a fire. your carpet burns well before the melting point of aluminum or copper. but, now that i think about it, in the case of a short, the copper can melt before the fuse goes. high current through a very resistive contact. the resistance of the contact area will build heat much faster than the very low resistance of the fuse. after all, your short wont be a great contact, it'll barely touch some metal and "weld" itself to that spot instantly.