I'll be installing one amp rated at 1200w RMS but wired 300w X 2@4ohm and another rated 400w RMS wired 100w X 2@4ohm. Both amps will be mounted in back of my Scab.
Will 4 gauge to a fused dist. block then 8 to the amps be enough?

 

It wouldn't be for the larger amp but you could get away with it on the smaller one. Hope that helps

 

Accoring to the the www.streetwires.com calculator, you are right on the bubble with 4 awg or 1/0 awg. Better safe than sorry. I would run the 1/0 and split into two 4 awg.

 

you will be fine running 4awg.. If you look up the power handleing of 4awg cable and the distance of wire he is using. for only running 600watts (on a mono block) and 100watts on a a/b amp.

4awg will be percfectly fine. But its your money so it you want to splurge and send the extra $$ then get 2awg.. 1/0 is just a waste in every every way for your setup.

 

I also have a 1200 RMS amp and a 360RMS amp. I used 4 ga wire from the battery to the distro. block in the back of my last car. Ended up needing a 4ga to the big amp, better grounds, new alternator with 4ga. to the battery, battery blocks, and a capicator. Most of this stuff is easy to do the first time but will **** you off to have to "fix" a fresh install. I have these same amps mounted in the rear of my screw as well, check out my gallery if u wanna see how I went about it.

 

Like bushtree said, 1/0 is prob a little bigger than you need. And if you dont need 1/0, dont get it, its expensive as heck.

Id run 2 gauge back to a distri block then 4 gauge from the d-block to the amps. Thats what Id do anyway
Heck you could even get away with 8 gauge to the smaller 2 channel amp.

 

Go to this site and read section 14 on fuses and section 16 on wire.

http://www.bcae1.com

Also, you could check out www.the12volt.com

 

You know, I posted what Streetwires website listed but, I ran 4 awg to my Memphis Belle amp in my Acura TL and it was running at 1,000 x 1 @ 1ohm and 75 x 4 @ 4 ohms. 1,300 watts and I never had a bit of problems with it. Sorry, I should have remembered that.

 

Current capacities for given wire sizes are specified based on voltage drop and thermal rise due to the wire heating up while running continuous power.

One key thing to remember is audio is never continuous power draw unless you like listening to a continuous tones at high volumes. The average current is going to be quite a bit less than what the amp can handle continuously.

IMHO, there is some marketing going on here that's making all of us think we need power wires the size of the cables that hold up the San Francisco Golden Gate Bridge.

Me thinks 4-6AWG is plenty good for almost all car amp demands unless you're competing to rattle the city. THe ohmage and corresponding voltage drop for worst case ~10-15ft from the front to back of the truck is somewhat negligible. I'd also be more concerned about the resistance of all the power and ground connections along the path...

OTOH, if you're running a 1500W 12V->120VAC inverter and powering a 1HP pool pump with it all day, I'd start paying real close attention to wire sizes...