Amp has X2 - 30amp fuses, should I have a 60 amp fuse in my In-line fuse dist. block?

[falconman515]

I am buying an amp that has Qty. 2 - 30 amp fuses built in .... then about 18 back I currently have a distribution block (4g in 8g out) with an in-line fuse (currently has a 30 amp fuse in it).

Should I also have a 60 amp fuse in that in-line distribution fuse holder? Or is the 30 amp that's in there fine? (once again I have a 4awg wire from the battery going to this fuse block then 18" of 8awg wire to the amp ... this splitting block was placed here for another amp in the future)

Keep in mind this is not to be confused with my in-line fuse holder at my battery ... that location holds a 100 amp fuse.

Thanks so much for the info

Click to read more...

 

[trumpet 5,000+ posts]

Is the amp a speaker amp or a subwoofer amp? If it's a speaker amp you will probably be fine with the 30 amp fuse. The current draw with music playing should almost never be enough to cause that size fuse to open, unless you have an unusually inefficient amplifier.

 

[falconman515]

Is the amp a speaker amp or a subwoofer amp? If it's a speaker amp you will probably be fine with the 30 amp fuse. The current draw with music playing should almost never be enough to cause that size fuse to open, unless you have an unusually inefficient amplifier.

No the amp is a subwoofer Mono d-class Alpine amp (MRV-M500) powering a 10" JL Audio sub (W0).

Should I get the 60amp fuse in this case?

Just want to make sure I have the right fuse in the fused distribution block ... I know the amp has the x2-30amp fuses already but I'm sure having this secondary fused DB block is great as well ... just need to know if I should be running a larger fuse then 30? ... figured 60 would be the best best.

By the way the Fused Distribution Block is a single 4 in split into x2 AGU fuses out ... so I have one wired for this amp and the other open (no fuse in it yet of course, just the one for the sub amp right now) and ready for a 4-channel amp in the future when I start working on the highs.

EDIT:

I did find this in the Amp user manual ............

Battery Lead (Sold Separately)

Be sure to add an in-line fuse with the battery lead as close as

possible to the battery’s positive (+) terminal. This fuse will

protect your vehicle’s electrical system in case of a short circuit.

Consult the table below for appropriate fuse value and minimum

wire gauge requirement.

MRV-M500 ..........................60 amp fuse, 4AWG/21mm2

MRV-F300 ............................40 amp fuse, 8AWG/8mm

This kinda states the fuse by the battery should be at least 60 amps ..... I currently have a full 100 amp MAXI fuse at my battery .... but then my 4awg wire goes back to the amp and I am running into this split Fused Distribution Block > then from there the 18" 8awg out to the amp.

Does having the 60 amp fuse in that fused block still apply considering the manual says to have a 60 amp fuse for the MRV-M500???

Thanks so much for all the info guys. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[trumpet 5,000+ posts]

The amp, in theory, could pull 50+ amps of current, but with music playing it's going to be much less than that. You're not fusing for the amp, you're fusing to protect the vehicle should the wiring fail.

What the manual states for fuses is the fuse at the battery. You already have that covered. When you have a fused distribution block close to the amps the fuses are for the change in wire size and the convenience of disconnecting power in individual circuit branches.

 

[falconman515]

The amp, in theory, could pull 50+ amps of current, but with music playing it's going to be much less than that. You're not fusing for the amp, you're fusing to protect the vehicle should the wiring fail.
What the manual states for fuses is the fuse at the battery. You already have that covered. When you have a fused distribution block close to the amps the fuses are for the change in wire size and the convenience of disconnecting power in individual circuit branches.

So does that mean the 30 amp fuse if fine for my changing size of wire? going from a 4awg into a 8 awg.

Just need to make sure I am running the correct size fuse in this block for my set-up

 

[Spooney 10+ year member]

You could always just give it a shot. If the 30 amp fuse blows during normal listening conditions then you know that the distribution block will need that 60 amp fuse or at least something larger than 30 amps. If it doesn't blow then you have added protection for the amp and wiring. The smaller fuse will not hurt anything. It just may not stand up to everday listening

 

[ShayneF 10+ year member]

Any reason for NOT changing it to the right spec? Simple enough to put the right one in there isn't it?

If the 30 blows (which is certainly possible, if not likely) it may come at an inconvenient time, ie away from home etc. I would be putting in a 60.

 

[falconman515]

Any reason for NOT changing it to the right spec? Simple enough to put the right one in there isn't it?
If the 30 blows (which is certainly possible, if not likely) it may come at an inconvenient time, ie away from home etc. I would be putting in a 60.

There is ZERO reason not to ... IF that's the correct thing to do!!!

I'm not saying I "Don't" want to put in a 60 .... I just don't know if I'm suppose to in this situation.

Its a $5 pack of fuses for me ... I am down to leave it at 30 if that's what I should run or buy the 60 amps IF THATS what I Should run. (I just don't know is my question and I'm looking for the answer)

I just need to know which I should?

Is there a downside to running the 60amp if it way more then really needed? Can it hurt running a fuse larger then needed?

Based on my configuration I just need to know what I should do?!?!?!?!?!?

Just making sure I do this right and I am safe in the specific things in put in my truck is all.

Thanks for the info.

 

[falconman515]

I went ahead and just bought the 60 amp fuses.

Seems like from what I read online my inline fuse should be at least if not more then what the amps fuse/fuses combine ... so since there is 2x30amp fuses on my amp it only make sense to be running the 60 amp fuse right at my fused distribution block .... then I have the large 100 amp at the battery for solid safety.

I don't think the fused DB block is totally need but its there and installed (because my last amp did not have internal fuses) and if nothing else adds a second layer of protection above and beyond that built in amps fuses themselves.

I should be good to go hopefully.

 

[ShayneF 10+ year member]

Yeah, I agree you don't need that fuse. Given that it is not needed for circuit protection, it should be the same as the amp fuse. You should have no dramas now.

 

[n2audio 5,000+ posts]

A fuse should be sized small enough to protect the wire but large enough to provide adequate current for the component's (amplifier in this case) current demand. If the 30A wasn't blowing it was doing its job -- and it probably would never have been stressed unless you were blasting low frequency test tones.

60A is obviously going to allow plenty of current to flow, but the protection factor is much lower.

40 or 50 would have been a better choice IMO, but 60A SHOULD offer adequate protection in the case of a short.

 

[Rob444]

You're supposed to use
the equation to figure the fuse size. It's s Watts÷Volts=Amps, then add about 10% to that number and round up to nearest fuse amperage.

So 500watts ÷ 14 volts = 35 amps + 10%(3.5 amps) = 38.5 amp fuse. Round up to a 40 amp.

 

[Firewalker]

@Popwarhomie

 

[Popwarhomie 5,000+ posts]

You're supposed to use
the equation to figure the fuse size. It's s Watts÷Volts=Amps, then add about 10% to that number and round up to nearest fuse amperage.

So 500watts ÷ 14 volts = 35 amps + 10%(3.5 amps) = 38.5 amp fuse. Round up to a 40 amp.

10 year old post.