The New Guy’s quick questions.
Printed From: the12volt.com
Forum Name: General Discussion
Forum Discription: General Mobile Electronics Questions and Answers
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=58588
Printed Date: April 27, 2024 at 7:53 PM
Topic: The New Guy’s quick questions.
Posted By: 95oakmax
Subject: The New Guy’s quick questions.
Date Posted: June 29, 2005 at 9:44 PM
Hello, I'm new to serious car audio and I am also new to these forums. Over the weekend I will be installing a SoundSplinter RL-i 10" subwoofer and two MTX amplifiers to my aftermarket system.
I believe I have purchased everything for this set-up. I am nearing completion with my box, I have purchased 3 16' Lightning Audio BOLT RCAs, I have a few four-packs of ring terminals, in-line fuse block/fuse, a distribution block for the trunk, and even a decent amount of 16 gauge speaker wire.
One thing I am not sure about - my power/ground wire. I purchased 21 feet of no.4 THHN wire for this and just wanted to make sure this would be good enough wire for my application. (I have ~400 watts going to the sub and ~200 to the internal speakers)
Sorry to bother you all with this most-likely tired and frustrating wiring question - but as you might have guessed, I just am not sure of the answer.
-------------
-Jonathan
1995 Maxima GLE-JVC AR-5000 HU-Polk dB6750 Comps-Polk dB675 Coax-SoundSplinter RL-i 10"-Powered by MTX
Replies:
Posted By: dwarren
Date Posted: June 29, 2005 at 9:59 PM
Check out the Power and Ground Calculator to the left. Then feel guilty for asking questions like this.  -------------
Posted By: 95oakmax
Date Posted: June 29, 2005 at 10:15 PM
Sorry, perhaps I need to redirect my question slightly. I did not mean to ask whether or not 4 gauge wire would be sufficient, but rather I am asking about the type of wire. As I understand it, Monster-Cable type wiring has as many as 1800 strands of wire within a 4 gauge wire, whereas the THHN that I purchased only has around 16-18 strands.
As I have been taught the electrons flow only on the surface of the wire, and therefore more strands=more surface area=better transfer of electrons. However, others have also told me that the only difference the strand count makes is to the flexibility of the wire.
That was the nature of my question - "Is THHN good enough? or Should I eventually upgrade to Welding wire or Monster Cable (higher strand count)?"
I did take a look at that spreadsheet for Power/Ground wiring, thanks for pointing it out, it is quite useful.
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-Jonathan
1995 Maxima GLE-JVC AR-5000 HU-Polk dB6750 Comps-Polk dB675 Coax-SoundSplinter RL-i 10"-Powered by MTX
Posted By: forbidden
Date Posted: June 30, 2005 at 7:28 PM
The other thing to consider other than flexibility is this. The more strands, the higher the amount of surface area, next how's about the cables ability to take heat, moisture, cold etc. that an engine bay has? I would go to a good 4 gauge car audio cable if I was in your shoes. ------------- Top Secret, I can tell you but then my wife will kill me.
Posted By: Mad Scientists
Date Posted: July 04, 2005 at 12:27 PM
95oakmax wrote:
As I have been taught the electrons flow only on the surface of the wire, and therefore more strands=more surface area=better transfer of electrons. However, others have also told me that the only difference the strand count makes is to the flexibility of the wire.
AC flows on the surface of the wire, DC flows through the wire.. Jim
Posted By: boulderguy
Date Posted: July 04, 2005 at 8:41 PM
Mad Scientists wrote:
AC flows on the surface of the wire, DC flows through the wire.. Jim
No kidding? Ironic that home wiring is mostly solid while car is multi-strand. I'm sure this is primarily about flexibility tho. Any input about fewer strands vs many-strands? Mayeb there's a good post about this? Mostly interested for theoretical reasons. -------------
Posted By: wirewise
Date Posted: July 04, 2005 at 8:56 PM
Mad Scientists wrote:
AC flows on the surface of the wire, DC flows through the wire..
I was taught that electricity (AC and DC) flows on the surface of the conductor (wire). Do you have any reference to this?
~wirewise~
Posted By: Mad Scientists
Date Posted: July 05, 2005 at 5:19 AM
(First attempt to post seems to have locked up.. second attempt here.) certainly.. "As previously mentioned, the skin effect is where alternating current tends to avoid travel through the center of a solid conductor, limiting itself to conduction near the surface. This effectively limits the cross-sectional conductor area available to carry alternating electron flow, increasing the resistance of that conductor above what it would normally be for direct current: " https://www.allaboutcircuits.com/vol_2/chpt_3/6.html "When wire (specifically, solid copper conductors as are used for transformers) is used to carry DC current, the entire cross sectional area of copper carries the current equally. When wire is used for AC current, the current is carried differently. At low frequencies, the current flow is not significantly affected by the skin effect. As you get into the higher frequencies (as those used to drive a transformer in a switch mode power supply), the current flow is carried disproportionately by the outer area of the copper wire (especially for large single solid conductors). This is called the skin effect." https://www.bcae1.com/trnsfrmr.htm And I learned about this effect during Non Destructive Testing with Magnaflux machines.. "this type of current is passing through zero 120 times per second, the magnetic field it generates is not able to penetrate very far beneath the surface of the part. The current and the field generated stay near the skin of the part, no matter how high the value of current used. This is called "skin effect". AC works very well for locating defects open to the surface." https://www.magnaflux.com/files/library/Technical_Papers//Types%20of%20Magnetizing%20Current.pdf Jim
Posted By: thepencil
Date Posted: July 05, 2005 at 1:14 PM
wirewise wrote:
Mad Scientists wrote:
AC flows on the surface of the wire, DC flows through the wire..
I was taught that electricity (AC and DC) flows on the surface of the conductor (wire). Do you have any reference to this?
~wirewise~
I also carry the same concept as you wirewise until now. Great post Mad Sciencetist. Thanks. ------------- Be careful whose advice you buy, but be patient with those who supply it.
Posted By: 95oakmax
Date Posted: July 05, 2005 at 2:50 PM
Mad Scientists,
So basically you are confirming my belief that the strand-count in car wiring is only beneficial in terms of flexibility in the wire itself, am I correct?
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-Jonathan
1995 Maxima GLE-JVC AR-5000 HU-Polk dB6750 Comps-Polk dB675 Coax-SoundSplinter RL-i 10"-Powered by MTX
Posted By: oonikfraleyoo
Date Posted: July 05, 2005 at 7:37 PM
That seems to be what he is saying. I'd been told differently. Learn something new everyday. ------------- Nik
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