Hi!

I was messing with my amp the other day and while pulling it out the power and ground got caught on something yanking them out of the amp, shorting the power wires .... I saw a puff of smoke and some sparks. I figured, "well, that sucks, but I'm sure the fuse blew so the wires should be dead now". I went to go grab them and sparks started shooting... Good thing I only grabbed the insulation. I seperated the wires went up front and popped out the 30 Amp fuse... damn thing was still intact!

Shouldn't a short blow the fuse??? I mean my whole car could have gone up in flames! Anyways, I replaced it with a montster cable fuse setup... Should I try and blow it to make sure it works? Kind of an exepnsive test the monster fuses are like $1 each.

Just curious what others think about this...

Thanks!

-- Robert

 

Why didn't you disconnect the negative on the battery before you did that? Play safe!

 

Yes, yes. I agree, next time I will disconnect the battery first (pulling the fuse seems easier to me). Still, shouldn't the fuse have blown...

I've never really worried about being killed and such, even by my own stupidity. I have been electricuted 3 times now, once I had to go to the emergency room... missed my heart by an inch... burned holes through my hand and shoulder... (both entry and exit burns). I should add that I was only 6 at the time.. and don't remeber it at all.. was knocked out. Parents still tell me the story thou...

-- Robert

 

[QUOTE]Originally posted by Goldtrom
[B]Yes, yes. I agree, next time I will disconnect the battery first (pulling the fuse seems easier to me). Still, shouldn't the fuse have blown...

 

Pinky,

Your saying the fuse should not be in the engine compartment? Wouldn't that make it more then 1 foot? I have it right next to the battery, but the wire is like 8 inches long so I can move it around.

I just figured the clamping rate (think thats what surge protectors call it) was greater... like if I exceed 30 amps for .01 seconds it should blow.... I figured it may just be a slower fuse... still kinda scary.

Thanks everyone!

-- Robert

 

I have one of those Rockford clamp-on-battery terminal fuses for my amps. It uses an AGU type fuse. 4 gauge wire is such a pain to work with. In the trunk I have a distribution box with 2 fuses that split the power to 2 amps. Double protection and the the 4 gauge wire just screw clamps into the fuse holder and the box.

Disconnecting the negative terminal on the battery is so easy. 10mm wrench, loosen, then pull off. Then you're safe.

 

Fuses are slow to blow, at least compared to other electronic devices. A typical fuse will have specs like this:

Will carry 110% of rating for 4 hours
Will open (blow) at 150% of rating in 60 minutes
Will open at 200% of rating in 30 seconds
Will open at 275% of rating in 2 seconds

And this is for a "fast-acting" fuse .
So your 30 amp fuse could easily pass 60-75 amps for several seconds without blowing. That much current could cause considerable arcing and heat, and yes, even cause a fire. Heck, 75 amps is enough to weld with!!

Make sure the wire from the fuse to the device (amp) is big enough to carry this current (the 75 amps) for long enough for the fuse to melt, without getting hot enough to cause a problem.

Too small a cable can overheat and burn long before the fuse opens. This is part of the equation people often overlook when cabling up high-powered amps. They know that too small a cable will not provide the same power output, but don't always know the danger factor with a small gauge cable and high current fuses.

And yes, to provide protection for the wire, the fuse should be as close to the battery as possible.