Fuse sizes - what's the safest route?

[DejaWiz 5,000+ posts]

Hey everyone,

I'm making preparations to buy KnuKoceptz goodies to rewire my setup and wanted to double check myself.

First, my setup is as follows:

INFINITY 7541a - 4 x 111W RMS @ 4 Ohms

- gains set to deliver 100W to each mid and 60W to each tweeter to SPX-177R biamped.

INFINITY 611a - 1x456W RMS @ 4 Ohms

- gain set to deliver 400W to Assassin 12.

Doing the math, I come up with the following:

COMPS

(2 x 100W) + (2 x 60W) = 320W

320 / 12.5 = 26A

SUB

400W / 12.5 = 32

720W Total / 12.5 = 58A draw

For the power distro block, I'm choosing 2 40A fuses (1 for each amp).

For the main power run, I'm choosing an 80A fuse.

Does everyone concur that the above fuse choices would be sufficient for my setup? Should I go down in sizes? Should I go up in sizes?

Click to read more...

 

[squeak9798 5,000+ posts]

If the amplifiers have internal fuses then you base your in-line fuse sizes on the amperage draw the wire can handle. The fuses in the amplifier protect the amplifier, the fuses in the power wire protect the wire.

So, your question has no answer since we don't know what wire gauge you will be running.

 

[ultimate157 5,000+ posts]

If the amplifiers have internal fuses then you base your in-line fuse sizes on the amperage draw the wire can handle. The fuses in the amplifier protect the amplifier, the fuses in the power wire protect the wire.
So, your question has no answer since we don't know what wire gauge you will be running.

x2:uhoh:

 

[rollininstyle04 10+ year member]

If the amplifiers have internal fuses then you base your in-line fuse sizes on the amperage draw the wire can handle. The fuses in the amplifier protect the amplifier, the fuses in the power wire protect the wire.
So, your question has no answer since we don't know what wire gauge you will be running.

What size fuse should it be for a single 8 guage run?

 

[ultimate157 5,000+ posts]

What size fuse should it be for a single 8 guage run?

60amp. Check the wire guide sticky @ the top for more info.

 

[DejaWiz 5,000+ posts]

Damn, I did forget to mention I was planning on running 4AWG wire from the battery. Input on the 611a has to be at least 6AWG (I'm going to use 4AWG), and input on the 7541a has to be at least 4AWG (I'm going to use just that).

611a = 2x30A

7541a = 2x30A

So, 60A fuse for each in the distro, and 120A in the main. Sheesh it's been a long week... //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif

//content.invisioncic.com/y282845/emoticons/threadlocked.gif.19972dacc919d20277442a45eb2e99e6.gif (please)

 

[ultimate157 5,000+ posts]

Where the hell did people get the notion that you are supposed fuse for the combined amount on the amplifier?

 

[DejaWiz 5,000+ posts]

Okay, obviously I'm incorrect here. So enlighten me.

I ask for help and I get flamed..... //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif

Sadly, it seems so typical for a majority of the user base on this forum anymore. Did all the arrogant pricks from icix show up here recently? One would think some of the more experienced and seasoned members here would realize that not everyone is a fvcking car audio know-it-all. That being said, if you don't wish to share your *infinite wisdom* with others by presenting information in a positive light, save yourself the trouble of acting like an real ******* and don't post.)

 

[type[s5] 10+ year member]

Check the wire guide sticky @ the top for more info.

x2. Your question will be answered there with a bit of reading.

 

[ultimate157 5,000+ posts]

Okay, obviously I'm incorrect here. So enlighten me.

I ask for help and I get flamed..... //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif

Sorry, that wasn't directed at you. People have been told that is the way to fuse your wire, which is totally incorrect. In reality, the fuse is to protect the wire, and your car, from burning to the ground. The only situation you would need to fuse for the amplifier is if it does not have an internal fuse, and therefore you should add a SECOND fuse right before the amplifier.

 

[DejaWiz 5,000+ posts]

1. People have been told that is the way to fuse your wire, which is totally incorrect.

2. In reality, the fuse is to protect the wire, and your car, from burning to the ground.

3. The only situation you would need to fuse for the amplifier is if it does not have an internal fuse, and therefore you should add a SECOND fuse right before the amplifier.

1. Agreed. Seems I have been grossly mislead, even by some installers at local shops. (hence my confusion and questions here).

2. I'll post exactly what it is I'm installing and what I found in the wire guide, so maybe that will help confirm some things.

3. I see. So the fused distro blocks are absolutely not needed in my situation since the amps are fused and the main power run from the battery is fused.

WHAT I AM INSTALLING

Main Power Run (from battery to distro, about 10 to 12 ft at the most) - 4awg

Distro to 611a - 4awg (from the OM = max current draw is 69A)

Distro to 7541a - 4awg (from the OM = max current draw is 85A)

What I gathered from the Wire Guide sticky

4 gauge: ~140 amperes

Class D (~70% efficiency) -

Class A/B (~50% efficiency) -

2 gauge: ~220 amperes

Class D (~70% efficiency) -

Class A/B (~50% efficiency) -

1/0 gauge: ~350 amperes

Class D (~70% efficiency) -

Class A/B (~50% efficiency) -

Now, should I increase the main power run to 2awg or 1/0awg since both amps will have a 4awg input or will 4awg be sufficient for their combined draw? What size fuse would be the best choice for each wire gauge choice?

1/0AWG = 160A (not to go too much higher than the max draw of the amps)?

2AWG = 160A

4AWG = 120A, no more than 140-150A for good (not the cheap ebay crap) 4AWG

Any input if I am finally starting to get this down properly and what needs to be changed? Thanks.

 

[ultimate157 5,000+ posts]

3. I see. So the fused distro blocks are absolutely not needed in my situation since the amps are fused and the main power run from the battery is fused.
Now, should I increase the main power run to 2awg or 1/0awg since both amps will have a 4awg input or will 4awg be sufficient for their combined draw? What size fuse would be the best choice for each wire gauge choice?

1/0AWG = 160A (not to go too much higher than the max draw of the amps)?

2AWG = 160A

4AWG = 120A, no more than 140-150A for good (not the cheap ebay crap) 4AWG

Any input if I am finally starting to get this down properly and what needs to be changed? Thanks.

Fused distro blocks aren't NEEDED but they are good to have. I have 1/0 to a Knu fused distro because the wire steps down to 4ga, so the fuses in the block are 125A.

I would upgrade to 2awg (Or 1/0 is the best IMO because you won't have to re-do your wiring should you upgrade later) because you are getting close, or maybe exceeding, the amperage draw for a 4awg wire.

 

[DejaWiz 5,000+ posts]

Fused distro blocks aren't NEEDED but they are good to have. I have 1/0 to a Knu fused distro because the wire steps down to 4ga, so the fuses in the block are 125A.
I would upgrade to 2awg (Or 1/0 is the best IMO because you won't have to re-do your wiring should you upgrade later) because you are getting close, or maybe exceeding, the amperage draw for a 4awg wire.

I guess that was one of my whole reasons for creating this thread after I checked the wire size sticky.... Would I be okay with running 4awg as the main run since my amps won't be drawing anything near their max rms (all drivers in my vehicle are 4 ohms). Did I just overanalyze this whole thing?

And if the amps each are internally fused for 60A, what harm is using 60a fuses for each in the distro? Why or why not?

Thanks.

 

[05AztecRed 10+ year member]

I guess that was one of my whole reasons for creating this thread after I checked the wire size sticky.... Would I be okay with running 4awg as the main run since my amps won't be drawing anything near their max rms (all drivers in my vehicle are 4 ohms). Did I just overanalyze this whole thing?

If you don't plan on running anymore additional amps, or upsing your current amp to a larger one in the future, 4ga. is fine. Otherwise go with 1/0, and fuse it properly!

And if the amps each are internally fused for 60A, what harm is using 60a fuses for each in the distro? Why or why not?

This has already been answered, you DONT fuse according to the amp, you fuse according to the WIRE size.. 4ga. requires a minimum of 120A, or some people use 150A. By putting a 60A fuse in there, you are limiting the amount of power that will flow thru the wire. In that case, you should've just installed a smaller gauge wire.

 

[DejaWiz 5,000+ posts]

If you don't plan on running anymore additional amps, or upsing your current amp to a larger one in the future, 4ga. is fine. Otherwise go with 1/0, and fuse it properly!

No, I don't have plans for upsizing the amps. What I have is what will be used for a long time to come until either the car dies or the equipment dies (at which point I will find replacements that do the exact same).

1. This has already been answered, you DONT fuse according to the amp, you fuse according to the WIRE size.. (4ga. requires a minimum of 120A, or some people use 150A).

2. By putting a 60A fuse in there, you are limiting the amount of power that will flow thru the wire. In that case, you should've just installed a smaller gauge wire.

1. Does it have to be this way and why? Why do I need to amp a 4awg wire to 150A if my amps will only draw a max of 120A? Wouldn't putting in a 120A fuse regardless if the wire gauge is 4, 2, or 0/1 offer overcurrent protection on the wire plus the amps themselves? And yes, I know that's why a majority of amps have internal fuses, but what if by some small chance they are out of spec and pop at 80A instead of their rated 60A for example... wouldn't I want proper fusing somewhere in the line so they don't fry?

2. So that would be 60A per amplifier in the distro block..... 120A total.

Main Line = 120A

Distro Block = 2 x 60A

Each Amp = 60A internally

...triple 120A protection.

Is this okay to do or not?

I'm just just asking why or why not this was a safe route to take. Seems to me that putting in large gauge wire with a smaller fuse would be a much safer and logical route than small gauge wire with a larger fuse. Better to have too much than too little with the same size fuse kind of thinking.

Is my line of thought here wrong?