What fuse Size do I need?

[Jd377 6]

I purchased a Sundwn 3000d last week and will be getting it in soon. I was just curious about what Size fuse I would need to run from rear battery to amp? 150a, 200a, or 250a? I currently have 150a fuses from my sundown 1200amp that I use to own. Now that I upgraded to the 3000d sundown, I wasn't sure what size fuse to run between this amp and rear batt.

[emh9009 199]

Of those I would go with 250

[Jd377 6]

Of those I would go with 250

Does that mean there is a different one you would pick than those sizes?

[emh9009 199]

Of those I would go with 250

Does that mean there is a different one you would pick than those sizes?

There is always 300 amp fuse. Less resistance, but more chance of wire failure. I have all 300 amp. I don't remember what the 3k fuse rating is though..

[16K 159]

get a 300 amp fuse for 3000wrms

[ricksi30 923]

Single run of zero gauge?

[bassahaulic 155]

From rear battery to amp you don't really need a fuse as the wire will be very short.

I'll use my own setup as an example.

See in this photo how short the power wires are? What part of the car could possibly short that out?

[vladd 26]

P/V = I

3000W/10V = 300A

3000W/12V = 250A

3000W/14V = 214A

[95Honda 486]

The sole purpose of the fuse is to prevent a fire, it is sized to the wire size and has nothing to do with the amp power...

[Jd377 6]

Ok I am using a single run of 0 awg. And yes my rear batt will be within like 3 feet of the amp or maybe even 2 feet. The amp will be sitting on my rear seat and the battery will be on the floor right in front of that seat.

[Jd377 6]

I ordered 2 250a fuses and 2 300 amp fuses. Which would be best to run from front to rear battery? The 250 or 300a fuses? I put one near front batt and one right before rear batt

[Ohjay 116]

300amp fuse is safe for 1/0 usually.

[jcarter1885 995]

Research buddy, the info was given to you earlier about fusing to the wire size. So find out what 1/0 wire should be fused at and go for it.

[vladd 26]

The sole purpose of the fuse is to prevent a fire, it is sized to the wire size and has nothing to do with the amp power...

By that logic are you saying the size of your wire has nothing to do with amp power?

[RiottStarr 5]

find a good circuit breaker.....never have to buy fuses and looks cooler.

[Impious 1,476]

The sole purpose of the fuse is to prevent a fire, it is sized to the wire size and has nothing to do with the amp power...

By that logic are you saying the size of your wire has nothing to do with amp power?

No, he's saying that the fuse is there to protect the wire from meltdown. It doesn't matter what amp is connected to the other side, the wire itself has a certain ampacity that if exceeded will become a fire hazard. This is what the fuse is there to protect against. So you fuse for the wire. The wire should be properly sized for the amp, and the fuse should be properly sized for the wire.

The one caveat I'll add is in the instance where the amplifier does not have any onboard fusing you would want to select a fuse size that will protect both the wire and the amplifier, but you would want to go with the most conservative of the two.

[Impious 1,476]

find a good circuit breaker.....never have to buy fuses and looks cooler.

They are also less reliable and more prone to failure.

[///M5 2,833]

find a good circuit breaker.....never have to buy fuses and looks cooler.

They are also less reliable and more prone to failure.

And in normal operation they shouldn't blow or trip which means its a huge waste of money. Add that to really liking to know when you have a problem so you can address it, I think CB's are a dumb alternative.

[Julian 641]

find a good circuit breaker.....never have to buy fuses and looks cooler.

They are also less reliable and more prone to failure.

Not stating this as fact, I had read after the first time the CB trip they become more inaccurate.

Is this true?

[vladd 26]

The sole purpose of the fuse is to prevent a fire, it is sized to the wire size and has nothing to do with the amp power...

By that logic are you saying the size of your wire has nothing to do with amp power?

No, he's saying that the fuse is there to protect the wire from meltdown. It doesn't matter what amp is connected to the other side, the wire itself has a certain ampacity that if exceeded will become a fire hazard. This is what the fuse is there to protect against. So you fuse for the wire. The wire should be properly sized for the amp, and the fuse should be properly sized for the wire.

The one caveat I'll add is in the instance where the amplifier does not have any onboard fusing you would want to select a fuse size that will protect both the wire and the amplifier, but you would want to go with the most conservative of the two.

This is what I was pointing out. If A depends on B and B depends on C then A does depend on C.

When I fuse I fuse the circuit, not the wire. If I know my circuit shouldn't pull more than 10A i'm going to fuse for that regardless of how big the wire is, so when the circuit pulls more than it should for any reason I'm aware (like a body screw that manages to penetrate the wire insulation or old insulation cracking and rain causing a short). Headroom may be good when choosing an amp but I don't like it with my fuses, that's room for trouble.

Alternatively, I cannot think of a reason to fuse higher than the circuit dictates, if there is one I'm missing feel free to enlighten me.

[An-i-no 86]

What Vladd said. His 3k may actually match the wire perfectly (in that they both need 300 amp fuses) in this case, but say he had a 1500. A 300 amp fuse on that is pointless. Yes you fuse for wire capacity at the battery but you fuse for amp capacity at the amp. Otherwise you might as well not even fuse at all.

EDIT: And say Circut Breakers were pretty reliable (not saying they are or aren't), you'd have to burn up a shit-ton of fuses before it paid for itself.

Not to mention that if you ever upgrade wire you have to buy a whole new one whereas you can simply replace a fuse/fuse holder for a hell of alot cheaper. If you plan on constantly exceeding the abilities of your wire then MAYBE you should get a circut breaker.....or you could actually fix the problem and get better wire/fuses....

Edited September 27, 2011 by An-i-no

[vladd 26]

What Vladd said. His 3k may actually match the wire perfectly (in that they both need 300 amp fuses) in this case, but say he had a 1500. A 300 amp fuse on that is pointless. Yes you fuse for wire capacity at the battery but you fuse for amp capacity at the amp. Otherwise you might as well not even fuse at all.

EDIT: And say Circut Breakers were pretty reliable (not saying they are or aren't), you'd have to burn up a shit-ton of fuses before it paid for itself.

Not to mention that if you ever upgrade wire you have to buy a whole new one whereas you can simply replace a fuse/fuse holder for a hell of alot cheaper. If you plan on constantly exceeding the abilities of your wire then MAYBE you should get a circut breaker.....or you could actually fix the problem and get better wire/fuses....

Just to clarify, it's not pointless, just provides no advantage over a 150A fuse, while a 150A fuse does provide advantages over a 300A fuse....allowing less unwanted current through the circuit.

[An-i-no 86]

What Vladd said. His 3k may actually match the wire perfectly (in that they both need 300 amp fuses) in this case, but say he had a 1500. A 300 amp fuse on that is pointless. Yes you fuse for wire capacity at the battery but you fuse for amp capacity at the amp. Otherwise you might as well not even fuse at all.

EDIT: And say Circut Breakers were pretty reliable (not saying they are or aren't), you'd have to burn up a shit-ton of fuses before it paid for itself.

Not to mention that if you ever upgrade wire you have to buy a whole new one whereas you can simply replace a fuse/fuse holder for a hell of alot cheaper. If you plan on constantly exceeding the abilities of your wire then MAYBE you should get a circut breaker.....or you could actually fix the problem and get better wire/fuses....

Just to clarify, it's not pointless, just provides no advantage over a 150A fuse, while a 150A fuse does provide advantages over a 300A fuse....allowing less unwanted current through the circuit.

Yeah my wording was a little strong. I just meant that the 300 amp fuse is not REALLY doing its job as it may allow the amplifier to exceed its limits while staying fully intact, thus defeating the purpose of fusing at all.

[vladd 26]

What Vladd said. His 3k may actually match the wire perfectly (in that they both need 300 amp fuses) in this case, but say he had a 1500. A 300 amp fuse on that is pointless. Yes you fuse for wire capacity at the battery but you fuse for amp capacity at the amp. Otherwise you might as well not even fuse at all.

EDIT: And say Circut Breakers were pretty reliable (not saying they are or aren't), you'd have to burn up a shit-ton of fuses before it paid for itself.

Not to mention that if you ever upgrade wire you have to buy a whole new one whereas you can simply replace a fuse/fuse holder for a hell of alot cheaper. If you plan on constantly exceeding the abilities of your wire then MAYBE you should get a circut breaker.....or you could actually fix the problem and get better wire/fuses....

Just to clarify, it's not pointless, just provides no advantage over a 150A fuse, while a 150A fuse does provide advantages over a 300A fuse....allowing less unwanted current through the circuit.

Yeah my wording was a little strong. I just meant that the 300 amp fuse is not REALLY doing its job as it may allow the amplifier to exceed its limits while staying fully intact, thus defeating the purpose of fusing at all.

The 300A or main fuse won't help the amp from exceeding its limits, that's what the amp fuses are for. The fuse at the battery simply serves as a fuse closest to the source of the electricity in an attempt to eliminate the chance of a short circuit. The difference is that there is zero need for this fuse to be larger than the circuit it's on dictates.

[An-i-no 86]

What Vladd said. His 3k may actually match the wire perfectly (in that they both need 300 amp fuses) in this case, but say he had a 1500. A 300 amp fuse on that is pointless. Yes you fuse for wire capacity at the battery but you fuse for amp capacity at the amp. Otherwise you might as well not even fuse at all.

EDIT: And say Circut Breakers were pretty reliable (not saying they are or aren't), you'd have to burn up a shit-ton of fuses before it paid for itself.

Not to mention that if you ever upgrade wire you have to buy a whole new one whereas you can simply replace a fuse/fuse holder for a hell of alot cheaper. If you plan on constantly exceeding the abilities of your wire then MAYBE you should get a circut breaker.....or you could actually fix the problem and get better wire/fuses....

Just to clarify, it's not pointless, just provides no advantage over a 150A fuse, while a 150A fuse does provide advantages over a 300A fuse....allowing less unwanted current through the circuit.

Yeah my wording was a little strong. I just meant that the 300 amp fuse is not REALLY doing its job as it may allow the amplifier to exceed its limits while staying fully intact, thus defeating the purpose of fusing at all.

The 300A or main fuse won't help the amp from exceeding its limits, that's what the amp fuses are for. The fuse at the battery simply serves as a fuse closest to the source of the electricity in an attempt to eliminate the chance of a short circuit. The difference is that there is zero need for this fuse to be larger than the circuit it's on dictates.

Yeah that's what I meant. Amp fusing. (as in amps with no onboard fuses) the op is asking about fusing his Sundown 3k. A fuse larger than what the amp can draw isn't really protecting it. In this case both the wire and amp require 300 amp fuses but that's not always the case, which is the point I was trying to make.