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Quick question

 

Bronze Member
Username: Sancho886

El Cajon, CA US

Post Number: 40
Registered: Jun-04
what size fuse should i use on the wire running to my amp? i have an earthquake phd-2.its 2000w rms. i am running 0 gauge wire if that makes a difference. i used to have a 100 amp breaker on 4 gauge and it never tripped. thanks for any info.
 

Silver Member
Username: Carguy

Post Number: 559
Registered: Nov-04
Hey Roger, look at the fuses on your amp. The total of those should be the fuse size for the power wire.
 

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 6009
Registered: Dec-03
well if the amplifier is truly 2Kw, and you have it wired at a load which produces 2Kw, and this is a class D amp, you'd need a 200A fuse.
Now, if you don't run the amp at full output, it's overrated, or you have it wired for a greater than minimum load, that fuse size can be safely decreased without blowing it.
 

Bronze Member
Username: Sancho886

El Cajon, CA US

Post Number: 41
Registered: Jun-04
issac, are these fuses on the inside? it doesnt have any on the outside. glasswolf, it is a class D amp. i probably won't be running it all full output and i have never had it bench tested so i don't know if it really does put out 2000. so how do i know what to decrease fuse size to? thanks.
 

Silver Member
Username: Carguy

Post Number: 570
Registered: Nov-04
Hey Roger, the fuses are usually located on the outside of the amp. If you don't see any then it must be a very old amp.
For 0 gauge wire, and assuming your alternator can handle it, you can try 100A for starter. If it doesn't blow then you won't need anything larger. I'm guessing your amp is 2000W peak power. This could mean in rms, it might be in the range of 600W - 100W.
 

Bronze Member
Username: Sancho886

El Cajon, CA US

Post Number: 42
Registered: Jun-04
isaac, the amp is 2000wrms @2ohms. 3000 peak. i will try a 100A fuse to start with. thanks a lot for your help guys.
 

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 6023
Registered: Dec-03
check the amp's manual
it should specify fuse requirements.

figure a class D amp is about 80% efficient.
2000 watts on a 12 volt system is 2000/12
that's 166.666666666666667 amperes
then multiply that by 1.2 to add that extra 20% you'll lose to heat and other parasitic losses.
you wind up with 200 amperes. (volts * amps = watts) so that's the fuse size you'd need for an amp that's actually putting out 2Kw.
Now as I noted, remember that's at full output.
every time you decrease audible volume by half, you reduce power usage by a factor of ten, so at half of full output from that amp, you're only drawing an average of 20A of current.
This is why a 100A fuse isn't blowing on ya most likely.
you also have to remember a 200A ANL fuse doesn't blow the instant it sees 200A of current.
It's rated on a curve so that the greater the percentage of over-current it sees, the shorter it's burn time gets.
at 10% over-current the fuse can hold out for as much as 4 to 5 hours.
at 25% though, that drops to something like 5 minutes. I'd have to check the chart to see the actual overcurrent vs time curve.
 

Bronze Member
Username: Sancho886

El Cajon, CA US

Post Number: 43
Registered: Jun-04
aaa i understand. thanks a lot glasswolf.
 

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 6028
Registered: Dec-03
no problem, Negotiator
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