This is precisely why I'm still researching this, and STILL pretty concerned.

There's WAY too many conflicting 'opinions' on what the actual electrical happenings are.

If we go by the Watts = Voltage x Amperage, when you do the backwards division, a 60W signal running at full bore (12V) would basically mean a 5 amp current flow.

Now, granted, this entails basically a SOLID fully amplified signal, which would never ever happen in the real world. But some serious bass laden music could approach a reasonable portion I'd imagine; maybe 70-80% of the signal max for short durations.

According to the American Wire Gauge table, based on those numbers, to safely carry a 5 amp signal in any conditions would require 14 gauge wire. Given that it's roughly accepted by most that a musical signal will not be a straight amplified power transmission signal, (nor will it be played at full volume and full gain) the next commonly available gauge wire down (16) seems like a sensible safe margin. (16 gauge is supposedly good for 3.7 Amps continuous power flow, according to the AWG table)

None of this takes into account the length of the wire run though. And from what I read, those AWG table numbers are based on the wire not being in a bundle, are based on conservative ratings for quality of copper, insulation, etc.

So, yeah. Even with all that, I'm still unsure what the 'right' answer is. Anecdotally, many have said they ran 75W RMS Amps on factory wire and it never incinerated their vehicle. Some of those people further claim that using the 18 gauge factory wire in that wattage range is 'ok', but fidelity suffers dramatically.

I guess it may come down to the fact there is no 'right' answer. Just what someone is willing to do. Go through the ridiculous effort to get new wire run through the molex plug, or take the factory harness shortcut. To me, since we're pursuing real audio quality to begin with, cheating with the factory wiring seems like it might be a poor choice.

I had emailed Bartak for his opinion, and he suggested an interesting 'alternative'; splice the new wire into the factory harness RIGHT before it goes out the door sill. In that way, essentially the only factory wiring is from the molex plug to the speaker; a short 18" (tops) run that is sealed inside the door, where there's basically nothing that can catch fire. This doesn't really resolve the audio fidelity argument though; if you drop from the new audio grade wire to the factory 18 gauge, whatever signal you may have preserved will still probably get horked once it gets carried down that short run of 18 gauge. (not to mention whatever resistance encountered in the molex plug pins)

<shrug>



I'm not an Electrical engineer; but I've read a bit on the matter. If there's a REAL EE around, and I've made any poor presumptions or theoretical errors in my analysis, please do correct me.

Otherwise, I guess I'll just keep digging for now.....

E.

 

I've been installing car stereo systems for over 25 years. The wiring in the OEM Ford harness will easily handle 100 watts with no distortion. And that's what we're really worried about (distortion) when we're talking about speaker wire gauge. Bigger is typically considered better, but it's often not required. The runs inside your average amp are less than 22 gauge in thickness anyway. Low frequencies (woofers) can benefit from monster cable, especially if they're located far (15 feet+ of wire length) from the amp.

In my 2007 FX4, I have the OEM wiring tied to 200 watts per speaker. Sounds fine.

 

You have to take into consideration what the insulation is made out of when sizing wires. A 14ga wire can handle much more then 5 amps. OEM wiring on a 5 amp circuit would probably be 18 or 20ga.
Lets take a worst case scenario, the blower motor.
It can run on high for hours and it's protected by a 30 amp fuse and uses 12ga wire.
Another scenario is the 4x4 shift motor, it's protected by a 30 amp fuse and uses 14ga wire. It only operates for a short period of time.

 

Ok. So you don't believe me when I say that your speaker wire will not melt or catch fire. And you say that you want some kind of proof that I even know what I'm talking about. Go to Rockford Fosgates website, look up amplifiers, pick out the T40001bd (mono channel 4000watts RMS) . Look under the specifications tab for this amp and tell me what range of speaker wire do they recommend with the use of this MASSIVE amplifier.

http://www.rockfordfosgate.com/produ...n_US&p_status=

Once again I reiterate that watts will not melt or incinerate your wires, The amperage is dangerous and is not an issue because the amperage is controlled by the amplifier. Only the volts are increased (during the second stage of amplification).

These cars that are burning to the ground are doing so because the installer overlooks the need to properly protect the system from the amperage draw from the battery. Most modern cars require cold cranking amps that range from 400 to 600. Sports cars and light trucks require higher cranking amps ranging from 700 to 1000 A. This amperage can easily exceed the capacity of the wire.

Read step 7
http://www.caraudiohelp.com/how_to_i..._a_car_amp.htm

 

were not talking about power wire or amp installation here were just talking about speaker wire here, lets assume we all know how to install an amp using proper sized wire and the right fuse withing 18 inches of the battery,

 

And that is exactly what I am talking about. I was simply stating that the real risk of a car fire is from the power wire from the battery to the amp. Not the speaker wire.

There is no risk of fire using the factory OEM speaker wire (like I've said twice before). Its a myth, an urban legend or whatever you want to call it.

Even Rockford Fosgate states that 18AWG is within suitable range for its 4000watt/RMS single channel T40001bd. Does anyone really think they would state this if there was even the slightest chance of a fire?