In Line Fuse Help - M Series Amps

[HD_Goofnut]

Hi guys.

I am just putting together the list of parts to order for my install but I can’t seem to find the info I require on amp fuse sizes.

I have an M44, M50 and M100 to fit but I wanted to know what fuse size I should be adding to the power distribution.

I’m running 0AWG from the battery to the trunk, then this is going to be split to feed the M44 and M50 on 8AWG and the M100 on 4AWG.

Any help would be greatly appreciated & thanks for reading

[ttocs]

For the 100 and the 50 it depends on what impedance your running them at. Check the manuals.

http://download.phoenixphorum.com/Manua ... s/M100.PDF
http://download.phoenixphorum.com/Manua ... ps/m50.pdf

The m44 doesn't have the same listing but says 30 amp fuse in the electrical section.

[HD_Goofnut]

All of them will be run at 4ohm bridged

Thanks for the links, I have already looked through the manuals but nothing stood out which is why I asked.

[Jacampb2]

You should fuse for the wire ampacity, not necessarily the amps current draw. It won't hurt to go lower than the wires ampacity, but if you are just looking at the amps ratings you can end up over fused for your wires.

The m series amps are internally fused. The best practice would be to fuse the distribution for the wire ampacity. This way you have room for upgrades later on.

[HD_Goofnut]

I understand about fusing the wire but was told if I fuse lower than the amps I will keep blowing fuses.

All I could see on the manuals was a mention of 40A maximum.

[ttocs]

m100 manual says 4 ohm mono needs 70 amps
m50 manual says 4 ohm mono needs 35 amps
and the m44 says 30 amps.

I question if this is correct though as its going to give you 4 channels with the two amps bridged. But going ahead with it then you power wire needs to be able to supply 135 amps to the distr block where you can then break the fuse ratings down to what is recomended for each amp

[HD_Goofnut]

All the amps will be running bridged, the M44 will be bridged and used to run the tweeters.

I want to use 8 AWG for the M50 and M44. If I remember correctly 8 AWG is good for 50A and up to 500 watts.

For the M100 I am looking at 4 AWG, again if I remember correctly that should be good for 125A/500-1000 Watts.

The main feed (fused by the battery) will be 0 AWG. This is good for 325A? I will also be upgrading TB3 with 0 AWG.

Does all that make sense?

[ttocs]

sounds good

[HD_Goofnut]

Thank you.

[ttocs]

Thank you.

post pics

[Jacampb2]

I understand about fusing the wire but was told if I fuse lower than the amps I will keep blowing fuses.

True, but if you fuse higher than the wire can supply you a) have the wrong wire, and b) are risikg a fire.

The m100 had an internal 80a fuse, the m50 and m44 have internal 40a fuses. Fuse for the wire ampacity, not the amps. These amps are already fused.

[HD_Goofnut]

post pics

Will do

True, but if you fuse higher than the wire can supply you a) have the wrong wire, and b) are risikg a fire.

The m100 had an internal 80a fuse, the m50 and m44 have internal 40a fuses. Fuse for the wire ampacity, not the amps. These amps are already fused.

I understand that, are you saying this (quote below) is wrong?

I want to use 8 AWG for the M50 and M44. If I remember correctly 8 AWG is good for 50A and up to 500 watts.

For the M100 I am looking at 4 AWG, again if I remember correctly that should be good for 125A/500-1000 Watts.

The main feed (fused by the battery) will be 0 AWG. This is good for 325A?

[Jacampb2]

No, I'm not saying you are wrong, those fuse sizes are fine. I'm saying that you are asking the wrong question. If you fuse for an amp and don't consider what the ampacity of the cable is, then you can wind up in trouble.

You've done your research though and have come to the right conclusion, but if you get in the habit of fusing for an amp, you can overlook problems with your conductors. In the long run a fuse won't protect the amp from "being blown" but it will limit damage if there is a fault.

The only time you should be fusing for the amp is if the amp has no internal fuses. If it isn't fused, you should fuse within 18 inches of the power input.

Good luck!
Jason

[HD_Goofnut]

Thanks very much Jason, you had me worried for a bit!