Resistance in 70/amp amplifier fuse

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daveward

Member - Posts: 15

Joined: April 05, 2006

Posted: September 19, 2006 at 3:46 PM / IP Logged

I am a believer...fuses are my friends. But my new (and 1st) amplifier has instructions showing the use of 4 gauge wiring from the battery to the amp with an inline 70 amp fuse, nearest the battery. If I use two Amplifiers (I am), it says to add the power ratings together and get a bigger fuse. I have questions about all those requirements:

1. If the electrons are moving through the big fat 4 gauge wire doesn't the presence of a 70 amp filament create "bad" resistance?

These two questions may need to be answered together:

2. A fuse near the Battery or near the Amplifier, it makes a difference?

3. With two amplifiers, there could be a 140 amp fuse??? Doesn't it make more sense to put two 70 amp fuses near the amps, one in each power line?

Thanks Very Much...Dave

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DYohn

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Joined: April 22, 2003

Location: Arizona, United States

Posted: September 19, 2006 at 4:01 PM / IP Logged

1) No

2) Fuses go on the battery end of the wire, as close to the battery terminal as possible. The fuse is to protect the WIRE, not the amplifier. The wire needs to be sized properly to supply the current your amps require.

3) The fuse size should be set depending on the current capacity of the wire. See the "Power and Ground" guide in the links on the left side of the forum.

If your amplifier does not include an internal fuse, then you need TWO fuses: one near the battery to protect the wire and a smaller one at the amplifier properly sized to protect the amplifier.

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daveward

Member - Posts: 15

Joined: April 05, 2006

Posted: September 20, 2006 at 11:27 AM / IP Logged

Gentlemen,

Thanks very much for the answers. They are very helpful. I'll just clarify some of my points and if you want to comment, that would be great.

1. I used the phrase "bad" resistance knowing that any resistance is to be avoided. My question relates more to the mental picture that is painted by the amplifier's instructions. They stress that the power requirements could only be met by using this big fat 4 gauge wire, yet all that power has to be funneled into one relatively tiny fuse filament. Perhaps my interpretation of resistance is wrong...but if one uses the water

and pipe analogy, the fuse filament would definitely create resistance...wouldn't it?

2. Great, helpful comments on the placement of the fuses, makes perfect sense now.

Thanks again. Now...a more practical question: I have ATC-style fuses throughout the car, but I've never seen these fuses at larger amperages. What fuse styles do you use when you have to use larger sized fuses?

Dave

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DYohn

Moderator - Posts: 10,741

Joined: April 22, 2003

Location: Arizona, United States

Posted: September 20, 2006 at 1:07 PM / IP Logged

The "water pipe analogy" does not always work with electricity. While some people claim sonic performance differences with different kinds of fuses, your concern is really not worth wasting any mental energy on. Look for ANL-type fuses. Or circuit breakers.

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Resistance in 70/amp amplifier fuse

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