Looking for some Power Wire Gauge advice

Flyin11

Member
2007-09-26 1:29 pm
Hey guys...Just finished up installing my new HU and that thing is awesome!!! I especially loved the hitting from the subs when I went from 60hz to 50hz on the HU :eek: :D Didn't have the 50hz for a low pass option on my other Kenwood.

Anyways, the point of this thread is this. I was looking on a site that had calculations for amp draw and wire size and all of that like Perry's. I figured give it a shot and when I put int my JL Audio'a RMS which is 500 into 1 on a 2ohm load and my wire size I have right now which is 8 gauge, it said I needed to go higher to 4 gauge. If it's not one thing it's another, just when I think I'm about done I might have to rewire my amp and spend more money but if it is needed then it is needed. I called Crutchfield and one of their guys suggested to defiantly upgrade to 4 gauge cause he didn't think I would be able to get by with the 8 gauge I would have on the A1400. He said I would have too much heat from the electrical flow and could be damaging. I told him I'm running the Alpine MRP-M450 on 8 gauge and he said that I was just probably able to get by on that amp but the JL draws more current. I don't want to start a fire inside my car or melt something :cannotbe: So If I have to it would only cost me about 35-40 dollars to get the cable I need and stuff. I just didn't really want to go through all this but I'd rather have the JL than the Alpine. Sorry to open up any old wounds for anyone around here as I know their have been heated discussions about Power Wire gauge and I'm just looking to see if anyone thinks I need to go to 4 gauge wire?
 

jol50

Member
2007-11-08 2:14 am
I bought a kit at walmart for $34 I think, for two amps. It is 5ga and supposedly good for 1,000watts but depends on who you ask. Anyway the amp is 700 and max is 920. I'm not sure about heating, you usually just lose voltage and your amp will not perform as well. I don't know how much draw 8ga takes before heating, but I ran a 300 and a 80 all wrms on 8ga for a while (out of the fuse box too) and had no problems. I hardly ever crank it wot for long anyway so I don't care that much if I lose a tiny bit of max bass with my 5ga, if it even does. But the kit had trigger wire, two nice RCAs, ground wire, and some other stuff including a block to spit it and the fuse block/fuse plus some 8ga for the short split to amps wire. I only have a 5ch in there but used most of it...but soon I'll have different amps. They will be rated at less wattage, but I fully expect it to go louder.
 

Flyin11

Member
2007-09-26 1:29 pm
I think I'm just going to get it over with...I won't have to worry about the wire gauge ever again as this is as high amp wattage as I will ever go and after the next few years, I'm going to be too old for this stuff and will just have a stock deck...So this is my last chance to really have a enjoyable system so might as well do it right and not have to worry about it later. Hardest part is going to be to find out where Circuit City stuck my 8 gauge power wire through the front of the car. Once I find that I can just go back through it from the outside and pull it through. I will then have to find somewhere to ground it. Didn't really want to put anymore holes in the floor boad but will have to now. So, I will have 4 gauge power and ground wire with 12 gauge speaker wire and should be good to go.
 
What kind of car do you have? Usually we run the power wire down the driver's side somewhere near the brake booster. Sometimes we are lucky enough to find a grommet to run the wire through. I have two 4 gauge wires in my car, it was easier to hide instead of having one huge wire.



Flyin11 said:
I think I'm just going to get it over with...I won't have to worry about the wire gauge ever again as this is as high amp wattage as I will ever go and after the next few years, I'm going to be too old for this stuff and will just have a stock deck...So this is my last chance to really have a enjoyable system so might as well do it right and not have to worry about it later. Hardest part is going to be to find out where Circuit City stuck my 8 gauge power wire through the front of the car. Once I find that I can just go back through it from the outside and pull it through. I will then have to find somewhere to ground it. Didn't really want to put anymore holes in the floor boad but will have to now. So, I will have 4 gauge power and ground wire with 12 gauge speaker wire and should be good to go.
 

Flyin11

Member
2007-09-26 1:29 pm
Well, they didn't have any 4 gauge wire left and after talking with them, they were saying I should just be fine with 8 gauge. They said it's always a great idea and defiantly doesn't hurt to go higher up in wire and they complimented me for thinking like that but they said it's just more of a safety measure than anything else and that amp is only running 500w in a 2ohm load and might not even hit that high half the time. More like 480. So they said if anything happens, my fuse would blow and that is true...I do have a 40amp fuse under the hood like I'm suppose to. It's all about trying stuff...I'll try the amp out and if it doesn't sound to my liking then I will resell it on Ebay and keep the Alpine. They said that I'm in a position that people are rarely in...I have 2 great sounding amps now and can choose between them. The Alpine sounds great with my HU now, don't get me wrong, but I would love to have a JL Audio amp cause they are the top of the line, to compliment my JL subs. I also just want a little room in my gain settings...I don't want to turn it all the way up but I still want it to hit. The Alpine is 1 line away from Max and I don't want it drawing too much power. So will give this a go...

What kind of car do you have? Usually we run the power wire down the driver's side somewhere near the brake booster. Sometimes we are lucky enough to find a grommet to run the wire through. I have two 4 gauge wires in my car, it was easier to hide instead of having one huge wire.

Well, I had a huge issue in the beginning ppia...I have a 2003 Honda Civic EX Coupe and I tried to go through a gromet in the floorboard on the passenger side like a lot of people were illustrating and when I pushed it through it caught a wire and broke it. This was not good cause those were like 100 little wires going to the computer. After a lot of fighting with it and stuff, my dad and I got it spliced and jumped back together and I decided to let someone else do it cause I almost didn't either have my car running at all or cost myself $2,000 to have to get the electrical system fixed. I see they went behind the glove compartment and came out a gromet on the upper left side under the hood, right inline with the battery. Like I said above though...I think I will be just fine...
 

jol50

Member
2007-11-08 2:14 am
I think those guys are totally clueless and/or blowing smoke....someplace. Rarely two amps? I have over a dozen 100-1,000rms sitting here I can think of, many people I know into music do. I always have that many at my disposal in case I need X type/size amp.

If you have any notion of learning to do anything mechanical, you don't learn while not doing it. But that is up to you. I save too much money not to....well not save so much as use that money for all the other cool stuff I have. It is a matter of priorities for me. I could pay someone to do something for me, or buy a cool amp/PC part/vehicle accessory/home improvement/etc, etc.

8ga is pushing it for 500wrms, but that is a short car so I'd have to look it up and know the rms wattage of the amp. I think there is a page on Perry's site that calculates the loss for you.
 

Flyin11

Member
2007-09-26 1:29 pm
jol50 said:
8ga is pushing it for 500wrms, but that is a short car so I'd have to look it up and know the rms wattage of the amp. I think there is a page on Perry's site that calculates the loss for you.

I just looked on his site...This is what is under the wire gauge part for 8 gauge:


8 awg 52 amps 430 watts A/B 537 watts D Class

This is another D Class amp so, all good...
 

crs1

Member
2007-12-08 6:58 am
i have been installing car audio for the better part of 28 years now +i am an auto mechanic and have a degree in electronics engineering technology what you need to look at also is what is the amperage of your alternator alot of cars only have @ a 60 amp now with the smaller gage wire when you are running your head lights ,parking lights this time of year you blower motor for you heater that is a hell of a strain on the alt. with a bigger gage wire the current is able to flow easier with less strain on the amp & the alt. and also giving you a cleaner sound . i know this is over kill but in my 2000 chevy silverado i am running "00" then four gage off of my fuse block to my amps my amps are infinity 1600A & a 7541A with a total of 1044W RMS when i was running 4GA into 8GA my sound wasn't as clean the larger wire is much better
 
I would go with the 4 gauge. I've seen people run super thin wire and never have problems.. but I try to advise others to do it like I'd have it in my car. Yeah, it's kind of a pita, but I think the grommet on the right side near the battery is a good place. Otherwise drill your own hole but yeah, watch out for a/c and wires - ouch! And yes, your alternator is probably around 60 amps so you might want to upgrade that if you plan on going any higher than your current level.
 

Flyin11

Member
2007-09-26 1:29 pm
Yeah...I'm still thinking about it...Being as they were out of 4 gauge wire, and most the car places around here are as well, I'm probably going to be stuck with getting a stupid amp kit with half of stuff I don't need for $61-80 dollars when all I needed was about $40.00 worth of equipment. It's stupid now n days. You can't just get a amount of cable that you need anymore, you have to double your money on amp kits. How they make their money :rolleyes: Anywho...My biggest problem was trying to find out where they ran the power wire and I figured out how to drop the glove compartment down and saw where it went out at. So I don't think it will be a problem at all to push it through from the outside in and pull the new wire in there. I'm just not sure what I'm going to do yet as it sounds awesome right now and I would just hate to have to resell that JL Audio amp.

So, my alternator is 60amps....I get what you are saying and all...so if I do this with the wiring and all I should be ok? Also, you say if I go bigger I might need to upgrade the alternator...Everyone is telling me to get a 4 channel amplifier...If I did that later next year, would that make me have to upgrade the alternator? I mean...There is no onboard fuses with this JL amp unlike the Alpine which has 40amps on it and I have another fuse between the battery and amp at 40amps. So I think the JL would help me out on my electrical system being as it only needs a external 40amp fuse to run it. The Alpine has like double that right (40amps on the amp and the inline 40amp fuse)? Is that how it works?

Thanks....
 

Flyin11

Member
2007-09-26 1:29 pm
Hey Perry...Not sure how long it is but I found some at a local hardware store...Found this on a old thread for welding cable sizes and what they are equal to in gauge for power wire:

25mm (4ga), 35mm (2ga), 50mm (1ga), 70mm (0ga)

Size on the cable says 0.30 mm...What gauge would that be? Like 3ga or 5 ga???

I'll probably just get the amp kit though...I also have been thinking about getting maybe some 5 or 6 gauge wire...might that be ok?
 
I'm not sure what those measurements are. Solid 4g wire has a diameter of 0.2". The stranded 4g welding cable I have here has a diameter of ~0.25" (copper only). The outer diameter of the insulation is 0.41").

To convert any of these to mm (diameter), multiply them by 25.4.

The chart on the following page may be helpful:
http://www.engineeringtoolbox.com/awg-wire-gauge-d_731.html

When you're looking up wire sizes, don't confuse diameter (mm) with area (mm^2).
 

jol50

Member
2007-11-08 2:14 am
If a walmart near you has the kit I got for $34 I think it was, you could add the 5ga to your 8ga and be close to 4ga. Like I said it had RCAs, distro block, 100A fuse block, etc. Problem up here anyway is they thin out car stereo stuff this time of year. Kit was a Scosche, here I think this one for 32: http://walmart.scosche-cars.com/pro...1=132&productID=1476&walmartProductID=4213089
This kit was more useful to me because I needed some more RCAs anyway, wanted a distro block too.

Like I said before, you would be very happy with the sound of a high side amp. If you need a 2/4ch depends on if you run front and rear, and even then you can still run rear off HU and amp the front. If you want the rear to go as loud/sound good then get a 4ch, I do so it plays well when I am outside the car. You only need about 75wrms/ch to get it sounding reasonable and it should not take as much power as the sub amp. Can also run a 2ch on 4 speakers at 2ohms for extra power but no fader that way. This can work if rear speakers are mounted by floor or so you don't hear them that well, but an audiophile will tell you not to have any rears.
 

Flyin11

Member
2007-09-26 1:29 pm
I actually saw that a little while ago when I was searching around on the net...The 5 gauge wire would probably work as well as the 4 gauge would for my application. I just don't know if it's carried in the stores around here and I'm just going to probably head out to the Audio store again during lunch and grab 1 of the 61.00 kits they have. Better to be safer than sorry and if it doesn't work out for the JL and I end up liking the Alpine better, then no harm as it will help with that amp as well.
 

jol50

Member
2007-11-08 2:14 am
It says free shipping to your store, but if they don't have one on hand I'm sure you would have to wait a week or something with the holidays. See what I mean, for the $27 more you spend you could score a good 2ch amp on ebay shipped but if you want the other wire its up to you.
 

Flyin11

Member
2007-09-26 1:29 pm
ran into a bigger issue now...I went out and checked underneath the hood of the Civic and the alternator looks like it says AHGA50 not AHGA60...Hard to tell...but that leads me to believe that it's a 50amp alternator, not 60 and juding on this file I downloaded from here that I have been checking:

http://www.datafilehost.com/download.php?file=6d26c621

500watts on a 50amp Alternator at 13.8volts is overkill and it suggests getting a lower wattage system or bigger alternator. I know I won't be hitting 500 full time and there is voltage loss on distance from the battery and all that stuff...but I don't want to run into any issues with losing all power going down the highway because my alternator isn't charging enough. So it might be best just to be happy with what I have...based on my new findings..any suggestions? Maybe I'm just seeing it wrong...Looks like 50 instead of a 60...
 

jol50

Member
2007-11-08 2:14 am
A lot of people overrun their alternators. All that means is when you put that much draw on it you will drop down to 12.5v or whatever your battery is. After a while you will run the voltage of the battery down as it drains, but that would take a while if the alternator is supplying current as well. Alternators do not like that, it will shorten its life but like most things the more you run them the faster they wear out. However music RMS is rarely the full output of the amp unless you play a lot of sine wave stuff like bass tracks. You can just test the voltage while you run it and when it drops to 12.x you have gone beyond what the alternator can produce. Note the alternator can not keep up with music draw so it will dip then come back up....will have a delay to the demand. Most amps are unregulated so those will have less output in watts as the voltage falls from 13.8 or whatever the regulator of the alternator is running. Most cars never see the 14.4v new amps are rated at anyway, so unlikely you will ever see max advertised rms power from any amp you have. My kicker is something like 65w/ch and only 40 at 12v. Some old amps are rated at 12, thus the difference in output.
 

Flyin11

Member
2007-09-26 1:29 pm
Yeah..That's what I kind of figuring as well...You get power loss anyways from the length of the power wire from the battery and size and all. Also, like you said, I don't drive very long trips and the volume on the headunit is never going to reach full power, the gain isn't going to even be all the way up (probably half way on this amp), so it's not going to be thirsting for power and all. Plus, I just called my brother and he knows about electrical systems and says I should still be fine even if it is only 50amps on the alternator, and if not, he said I will find out quickly and will then know I need to upgrade my alternator LOL My brother is pretty cool on this tuff...My mom and dad would be scolding and yelling at me about it even though I'm 32 and it's my money :rolleyes: I called a auto parts store and gave them the part# and the guy said he's showing in their system that the alternator is 70amp. I should trust them more as they are a parts store. He said that's what they are showing on their screen and if Honda told me to call them and find out and if they didn't know, then it's gotta be the right stats. :cool: So I think i will be fine again and will try to find a wiring kit now...
 

crs1

Member
2007-12-08 6:58 am
no you don't need a bigger alt. just go with at least 4 GA but if you are able get 2GA and yes welding cable is fine in fact it has better insulation and if running it under the car like i do on my truck put it in split loom tubing and only use black cable ties thay are the only ones rated for automotive and outdoor use .
hell i run 4GA to the starter on my stock car and it is only a 4 cylinder neon
 

Attachments

  • dsc_5913.jpg
    dsc_5913.jpg
    52.8 KB · Views: 156