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Fuse to the wire or device?

jocanon

Member
I have an car amp that says to use a 50 amp fuse. However, the wire I am using is 4awg and I already have a 100amp fuse on it to protect the wire. Do I need an additional 50 amp fuse if the wire is already protected with the 100amp fuse?
 

jocanon

Member
I should also add that my only concern is safety of the passengers (and myself) on the boat, so I only care about protecting from fires. I do not care at all about protecting the amp for the amp's sake, unless it leads to a fire hazard.
 

Diver300

Well-Known Member
Most Helpful Member
I should also add that my only concern is safety of the passengers (and myself) on the boat, so I only care about protecting from fires. I do not care at all about protecting the amp for the amp's sake, unless it leads to a fire hazard.
It's a boat. If something catches fire, you may have nowhere to run. A 50 A fuse and holder is less than $10. I would fit one.
 

jocanon

Member
It's a boat. If something catches fire, you may have nowhere to run. A 50 A fuse and holder is less than $10. I would fit one.
I agree with everything you just said, except the price. I just bought one and it was more than $10. A marine grade (waterproof) fuse and holder are about twice that much. But your point is still valid.
 

Reloadron

Well-Known Member
Most Helpful Member
I would independently fuse the amp at 50 Amps off your bus which is fused at 100 amps. As mentioned, a fuse and fuse holder is inexpensive all things considered, even at $20. So your bus at the source is fused at 100 amps and your amplifier is fused at 50 amps.

Ron
 

crutschow

Well-Known Member
Most Helpful Member
Do you really have something else on the bus that will draw significant current?
It's unlikely that the car amp will draw anywhere near 50A (600 watts) continuous unless you are playing really loud music to multiple speakers.
A slow-blow fuse will minimum nuisance tripping from short transient currents.
 

jocanon

Member
Do you really have something else on the bus that will draw significant current?
It's unlikely that the car amp will draw anywhere near 50A (600 watts) continuous unless you are playing really loud music to multiple speakers.
A slow-blow fuse will minimum nuisance tripping from short transient currents.
Probably not, but I want to future proof it. It's on a boat. It's a car amp which is on a boat. I bought the boat a few months ago and apparently the previous owner did not understand the importance of using marine equipment on a boat.
 

Reloadron

Well-Known Member
Most Helpful Member
Probably not, but I want to future proof it. It's on a boat. It's a car amp which is on a boat. I bought the boat a few months ago and apparently the previous owner did not understand the importance of using marine equipment on a boat.
Years ago, Cris Craft Cavalier Express 1963.

Oh you want a starter for a 283 chevy engine. That will be $100. Oh you want a starter for one of the two chevy 283 engines used in the Marine version? That will be $250. Boats are fun. :) Actually that boat was a lot of fun. Pretty sure my first daughter was conceived on that boat.

Ron
 

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