Wire/Fuse Guide

[Quiet]

But I fuse for the wire, not the load. Different strokes...

[06RTCharger]

18 hours ago, jimdog32526 said:

Awesome!  Exactly what I needed to know!

The only reason I went with 150 and 120 is because that is what the amp manufacturers recommended in the instructions.  So I will up that to 300's and let the amp fuses do their job but keep the supply fused to 300.

Hold on. I just checked out ur amps manual. It doesnt have any internal fuses, u must fuse them by their guidelines. Im not sure why they would allow 1/0 power and ground but only 150A fuse. Im still learning tho, im new to this. Same for ur hifonics. If it doesnt have those fuses that plug into it, then follow the manual about fusing. Sorry bro, i assumed the amp had internal fuses, i thought u said they did. 

[audiofanaticz]

1 hour ago, srp365 said:

But I fuse for the wire, not the load. Different strokes...

imo that is stupid.

So you fuse your 1/0 for 350 amps, lets say a short happens.

You know how long that fuse will take to blow? A while, just because the fuse is rated at 350 amps, it may take over 500 maybe even 600 amps of current for 5, 10, 15 seconds maybe longer before blowing.

What is even worse you can take the same size fuse from the same manufacture or even a different manufacture and it will be completely different.

There is SO MUCH wack information in this thread it doesnt deserve to be sticky worthy.

So say you have a 1500wrms amp, your amp says to fuse at 150amps. You have 1/0 wire but you fuse it at 350 amps.

That wire will never see a 350 amp load in its life time with that amplifier, so why are you fusing it so high?

If the amp is only pulling 150amps max you will see no difference in anything no matter if your using a 150amp fuse, a 200 amp fuse, or a 350 amp fuse.

The larger fuse will not make your amp get more power, all that larger fuse will accomplish is a short ever happens it will take longer for that fuse to blow, and by that time your car may already be burnt to the ground.

Now where these even becomes another drastic change is if your running any time of supplemental battery in the rear, if so that is going to absorb even more of the current draw being pulled through your power wire leading up to the front.

AS always the fuse is their to protect the wire in case it gets damage, the fuse is not meant to protect the gear connected to the wire. If your amp is going to blow, it will blow regardless of a fuse being installed right before the amp or not.

Back when MECA based competition classes by fuse rating you had competitors running tiny MANL and ANL fuses running 5k+ rms amplifiers off of 60-100 amps of fusing to be put in the lowest classes.

[06RTCharger]

Is there a better general guide to follow for when people are wondering what size fuse they should use? Seems to be a common question here for newer members.

[audiofanaticz]

Buy a DC clamp meter, clamp your power wire and see what the max draw is when your stereo is full tilt. Fuse for as close to that as possible.

If you pull 180 amps use a 200 amp fuse.

If you pull 210 amps, a 200 amp fuse will still probably work just fine.

Or just buy a a few different size fuses. Instead of buying a 300 amp buy a 200 amp and a 250 amp, maybe a 300 amp if you think you will need it.

But start small with a 200 amp fuse, if it blows use a 250 amp fuse. If the 200 amp fuse never blows just leave it installed and your good to go.
Clamp meters can be very useful in the car audio industry for anyone that dicks around a lot, and you can get a halfway decent one from the craftsman professional line for $60ish use or $125-150 new.

 

[Skullz]

If you really need to use a guide, then i would use one from a welding company as they know more about the wire than any 99% of audio companies selling rebranded wire with their name slapped on it. The max recommendations are just that, the very max fuse you could use, but as "Brian" has said you want to fuse it lower to ensure it pops before a full blown inferno trashes your ride. I only use welding cable for various personal reasons, and i use TEMco as they have a 1 year full refund on the wire they sell at very reasonable prices.

https://www.temcoindustrial.com/product-guides/wire-cable-and-accessories/welding-cable.html#ampacity

Down on the bottom where the wire sizes are, if you click on the length and color it will show you the price for that length and diameter, which is pretty cool.

[audiofanaticz]

The Craftsman meter is not the fastest to respond meter, nor the most accurate but for measuring current for non critical applications it will get the job done.

Fluke is the go to meter (I have one of those as well), but to get a Fluke that will measure DC current your going to spend a few hundred bucks typically.

Even though a lot of the fluke meters say ac/dc clamp, if you read the specs they will say something like "400 amps ac current, 600 volts ac/dc voltage" (which means it will not measure dc current, just dc voltage).

So you gotta read the specs very carefully when looking at a Fluke meter because you wont be able to measure dc current using an ac only current clamp.

The only thing an ac current clamp only would be good for in car audio is pretty much measuring the ac amps coming out of your amp to measure wattage, but then that is still flawed since its been proven you cant clamp an amps output and get its real wattage output since an ac clamp meter and ac multimeter will not calculate power factor, phase angle, nor include the amps efficiency rating (which is typically not published by amp manufactures) and if it is the rating they give is typically only at 4 ohms. So if your amp is wired at 1ohm or 2 ohm, or half ohm you are pretty much clueless on that efficiency rating.

Here is that craftsman professional ac/dc current clamp meter I was referring too, looks like the price went down even more, so that means you could probably find used ones even cheaper yet.

http://www.sears.com/craftsman-professional-true-rms-ac-dc-clamp-ammeter/p-03473756000P?sid=IDx01192011x000001&gclid=Cj0KEQiAwMLDBRDCh_r9sMvQ_88BEiQA6zuAQ8e0xOj6_R1NZPs7o9dcXPm4tuG37mm7nnIBg1Gqpm0aAmAd8P8HAQ&gclsrc=aw.ds

[jimdog32526]

I worked out the fuse thing.  I will run 300A under the hood for the main wires, then after the Distribution block feeding the amps, I will use 120 for the HF amp and 150 for the SA amp.  that way the Distribution block will get full power and the amps will feed off of it as needed but wont exceed the manufacturers load recommendations.

 

 

[Quiet]

@audiofanaticz

I didn't tell anyone to run it that way, and I didn't say you were wrong, or tell you your info was "wack", but also I see it a different way. smaller fuses are going to have more resistance than a larger fuse. That's current limiting. May not be much, but it's current limiting. Now in the real world, if there's any real short circuit, either a cut in the insulation, or a wire pops out of the terminal on the amp, the current going through, even 500A on 1/0, isn't going to make the wire heat up enough to be an issue before the fuse blows... Still safe, in it's own context.

This is how it was explained to me, by Ray, and confirmed by a few other people I'd consider experts in the field. 

 

I purposefully didn't go on a rant before because opinions are different, even yours, and everyone gets so butthurt in here when your opinion misaligns in the tiniest way.

I can see why VS threads aren't allowed lol

[Jessica]

Wire ratings are different for DC than they are for AC. 

I'm not sure if the speaker wire guide takes this into account or not.

edit: plus, the length of wire is not really relevant in AC for car audio guys afaik.