power wire sizes

Very true... they recommend that length simply arbitrarily though (They must recommend a gauge of wire, to go along with that length?), the real importance of that recommendation is ironically the same reason that forbidden has been arguing...

They generally recommend you disconnect your battery's negative terminal for most stock automotive electrical work because it's simply a safety net - literally a catch-all for every single circuit in your car... and that's specifically because the car is used as a ground plane for everything, the battery is a voltage source for everything, it's always in the circuit when the car is not running.

However, for most car audio work south of the head unit, it's actually recommended that you instead disconnect the main fuse (which should be located within 18" of your battery, up front), which will break the circuit only for any electronics installed off of that main power wire - such as those you would be working on back there.

That will save you the hassle of having to reprogram all your radio station presets, and reset the clock(s) in your car, not to mention your car's ECU's memory, etc.

Thanks for the pissing match guys, feel better now? I think it's best to let us all know if you are in fact a person who has an direct relations to a manufacturer who is in fact trying to cram their companies beliefs down our throats, or are you the customers know it all best friend? If you are a manufacturer then I'm sure that we are all aware that no product is the best product for all applications, and that they all work differently in different applications or does your equipment work the best in all applications, a pretty arrogant assumption for arrogant replies like yours. What a person does with information is up to them, let them use it and make their own opinions. Maybe just maybe some of my experience in the last 16 years has come hands on and has been duplicated by the tech gurues at Rockford Corporation and other tech departments and they have asked us to do things a certain way in order to solve the problem, but now you wouldn't be privy to that information would you? Keep going on your path guys, I'll keep going on mine and I'm pretty sure that our paths won't cross. While I have always stated that I continually learn new things everday, I for one do not profess to know everything, unlike you, oh it must hurt you to be wrong now doesn't it!

I am actually just a lowly installer who can't even come close to your experience in the bay.  But I have done a lot of studying within my field to understand how things work.  This helps me in troubleshooting situations.  Do I claim to be right all the time?  Absolutely not.  I know I am wrong at times, and when someone shows me this is true, I always admit it.  I figure a little hurt pride is worth the lesson I learned.  And to tell you the truth, usually I find out that the hurt pride is in my own mind, and the others don't care.

Now I see above some pretty harsh accusations, and I just don't see them having any merit in the conversation.  Did either of us say our product was better than someone elses?  And the only manufacturer relationship even mentioned was from you.  You are the one using something you heard by a manufacturer, and trying to "cram their companies beliefs down our throats".  What we did was provide logic, reason, and the physics involved in a way to show what actually happens to support our position.  I don't see any of this from you to prove your opinion is sound.  You can definitely do what you want with the information we provide.  But don't make irrational, imagined accusations about what we said.  I don't know why you think your position is supported only on the basis that you have 16 years as an installer.  Because I know that Dan Wiggins (who was the one who said 16 awg wire is fine) resume beats that by far.  And I'm pretty sure Geolemon's does as well.

These are ironic (and emotionally charged) comments, as your original post would lead a reader to believe that they should - as a generalization - perform their install in the manner which you described.

There's a large distinction to be made, also, between arrogance and objectivity...

Interestingly --- many of your claims seem unfounded... you've stated numerous times in this one thread how many numerous years of experience you have... and now you reply to my posts with a very condescending attitude, throwing personal attacks (I am pleased that you found nothing objective to refute of my posts)...

I would say that it is not me that is posting "arrogant assumptions and arrogant replies". 

So - I solidly believe you should question strongly any information that you have that counters essentially what the "rest of the world" believes to be the truth, because most likely that information is a misunderstanding, or a misconclusion. 

I certainly don't know everything, I sure don't profess to... if I only post on topics that I can contribute postively to - that is much different...

Be thirsty for information, but also be willing to question and drop any of your existing information in favor of the new - because particularly in the past few years, large shifts are being made in the industry, new technologies emerging, many (most?) of them to tackle the traditional difficulties faced in the car audio installation bay... eliminating many "weakest links" that formerly had significant installation workarounds.

Regardless - always question the sources of your new knowledge, don't be afraid to challenge them - truths will always inherently withstand against attacks (and I don't use words like "always" often!) -and those confident of those truths won't fail to be able defend against (or mind) a little devil's advocacy.  Or if they aren't able to - that's why these forums exist.  Put something out there, and let the world try to slam holes through it. 

No kidding, deep indeed, my words were not intended to offend anyone and if I did, I can say I'm sorry, and no one is just a lowly installer, they are a valued member of a team. While I will conceed that there are definitely people out there who do know more than I do, there are also people out there that may know more than them. Now while the vast majority of installers do upgrade the ground at the battery (and in most cases they should), very few actually take the time to measure the resistance in the frame of the vehicle. This was my point. Some vehicles are great and we don't have the long procedure and extra cost to the customer of grounding direct to battery. I'm sure that we are all aware that they don't make vehicles like they used to. When I have a customer with his Rockford Power 1000 and he has blown it three times and each time it is directly related to a grounding issue and we follow the tech departments advice each time in order to solve the problem, well maybe the tech's had to do some reaching in order to help us solve this problem. Did the customer install it himself, yes, did he do the recommended upgrades each time, yes, and finally I was shown how to check the resistance on the ground return of the vehicle, problem identified and corrected with grounding directly to the amp. Do I ground all amplifier in this way for all of my customers, no I do not, I do however take the necessary steps I was taught in order to help prevent the problem from arising again. Have you guys out there ever tried this, maybe you should, it can't hurt at all. I learned something and will continue to learn more and expect to do so as well, even from your feedback on this site I would imagine. And yes I did actually find two vehicles with huge resistances on the ground returns, one a 2001 Ford Ranger, the other a 97 Chevy Cavalier, I would not have found this if I didn't know to look for it.

Now as for the speaker wire scenario hooking up to subs, yes I also agree that 16 gauge can be used to wire subs, why not 18 gauge or even 24. Now most people would say don't use 24 gauge, it can't pass the current, it's too small, maybe you will agree with this and if you do, great, if you don't great as well. I'm sure I'll see the techno garble up here to prove the point from someone. So next time wire your customer new subs with 24 gauge and hear how it sounds, then wire it with 16 gauge and compare the two. My point was that I will use a 12 gauge or even up to 8 gauge depending on the needs and capabilities of the system, and as a general rule I do use 12 gauge and most amplifiers also are designed for up to a 12 gauge for a reason, or does the tech guy who designs the amplifier not talk to the tech guy who hooks them up. So depending on the application, choose the appropriate wire size.