I have an MTX 2150x amp it is rated at 425 total watts. What inline fuse should I use..... 30, 40, 50, 60????????
thanks
Matt

 

ttt

 

60 amp fuse.

 

inline fuse near the battery depends on power wire gauge, not amp size. It's there to prevent a fire form the power wire shorting to the chassis. The internal amp fuse is there to protect the amp. Look up a table of power wire recommended fuse ratings on the net.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by darkvibe &raquo;</TD></TR><TR><TD CLASS="quote">inline fuse near the battery depends on power wire gauge, not amp size. It's there to prevent a fire form the power wire shorting to the chassis. The internal amp fuse is there to protect the amp. Look up a table of power wire recommended fuse ratings on the net.</TD></TR></TABLE>

Please explain the wire gauge/fuse rating relationship. So what fuse should he use in this situation?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vteg &raquo;</TD></TR><TR><TD CLASS="quote">

Please explain the wire gauge/fuse rating relationship. So what fuse should he use in this situation?</TD></TR></TABLE>

I was just saying I would get one thats the right size for whatever gauge power wire is used and never have to worry about it in the event of getting a new amp or whatever (assuming you can use the same size power wire thats already in there with the new amp.) The fuse can be as large as the max recommended current that the wire should carry and be safe. I'm not saying it's wrong to use the max current draw of the amp to size the fuse like it looks like you did, as long as it's not above what the power wire gauge should carry.

Here is a chart i found on the net.
I'd use one of these depending on the wire gauge. If the amp draws more than what this chart says for his wire gauge, he needs new power wire.

Wire Gauge Recommended/Maximum Fuse Size
00 awg 400 amps
0 awg 325 amps
1 awg 250 amps
2 awg 200 amps
4 awg 125 amps
6 awg 80 amps
8 awg 50 amps
10 awg 30 amps
12 awg 20 amps
14 awg 15 amps
16 awg 7.5 amps

His amp should draw about 40 amps i think. Amps=watts/volts =425/14.4 =30 then divide by the efficiency. I dunno what the efficiency should be so say like 70%. So 30/.7 = 43 amps. I assumed the 425 watts was peak.

I'd do 8ga wire with a 50 amp fuse. Where did your 60A number come from?

 

I calculated 60% efficiency.

There are too many variables to use generic charts. There is no reason to put a huge fuse if you can't draw anything close to it. The gauge of wire has nothing to do with the fuse that should be placed on it IMO. Voltage drop is a different story though. That is what the charts are based on.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vteg &raquo;</TD></TR><TR><TD CLASS="quote">I calculated 60% efficiency.

There are too many variables to use generic charts. There is no reason to put a huge fuse if you can't draw anything close to it. The gauge of wire has nothing to do with the fuse that should be placed on it IMO. Voltage drop is a different story though. That is what the charts are based on.</TD></TR></TABLE>

Agreed

 

I am no expert, but the gauge of the wire has everything to due with the size of the fuse. If the wire were to be grounded you want the fuse to melt not the wire. Putting a 50 amp fuse on a 12 guage wire, the wire will burn (and your car) before the fuse melts.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by eskoobie &raquo;</TD></TR><TR><TD CLASS="quote">I am no expert, but the gauge of the wire has everything to due with the size of the fuse. If the wire were to be grounded you want the fuse to melt not the wire. Putting a 50 amp fuse on a 12 guage wire, the wire will burn (and your car) before the fuse melts.</TD></TR></TABLE>exactly!

 

You guys that say it does have to do with acceptable fuse sizes, which it true, but vteg is right too. He never said it's ok to put a fuse in a wire that will carry more current than the wire is good for. The original post never said what gauge wire it was so i think we all assumed it was big enough.

I was just saying that IMO i put in the largest fuse rating that the wire should carry and never worry about it again. He was just saying that theres no point in putting a bigger fuse in than the amp can draw. His way is probably safer.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by eskoobie &raquo;</TD></TR><TR><TD CLASS="quote">I am no expert, but the gauge of the wire has everything to due with the size of the fuse. If the wire were to be grounded you want the fuse to melt not the wire. Putting a 50 amp fuse on a 12 guage wire, the wire will burn (and your car) before the fuse melts.</TD></TR></TABLE>

The amperage chart posted should be used, if you don't know how to calculate the needed gauge wire for your run. The fuse does not need to be at the maximum amperage though. I did not say it was good to exceed the maximum amperage on for the wire gauge.