Wire size argument

[MakeshiftAudio 10+ year member]

Energy is in the wave is determined by the frequency. I'm not sure that this can be applied to waves in a medium.

Though, the lower the frequency the more air that needs to be displaced to complete the full length of the wave. With subs, this can be considerably hard to do, so we use a quarter wave etc style.

wavelength=c/freq

In sound, c=340.29 m/s

340.29/40Hz=8.5m, which means the wavelength is about 8.5 meters, while something like 8000Hz, the wavelength is 0.0425m. With this short wavelength, it is possible to get the complete wave in.

Bleh, I'm not sure, but I think I'm in the right direction. I thought this thread was over wire size.

 

[McIntosh 10+ year member]

ask your dad how many watts rms he was running when he was a kid... lol

Truly funny. Ask yourself how many horsepower could be derived from a 15A outlet in your dad's day versus today. I certainly don't assume you'd be able to interpret the results. lol.

 

[IMOVeCHICKENS! 10+ year member]

seriously do 0/1 for your main power into a distribution block and than get what wire barely fits your amp because you will upgrade eventually.

 

[MakeshiftAudio 10+ year member]

seriously do 1/0 (also known as 0) for your main power into a distribution block and than get what wire barely fits your amp because you will upgrade eventually.

Fixed. Pet peeve of mine.

You could use reducers.

 

[Innovative:Cory 10+ year member]

On the amperage is amperage comment....

20amps of draw at 12.6 volt = 252 Watts of power @ 100% efficiency

20amps of draw at 110 volt = 2200 Watts of power @ 100% efficiency

Yes the amperage remains the same but the power output differs... on the back of almost every electronic device ment for use on A/C has a label (UL or whatever) that lists power consumption of the device...

For instance the monitor on this computer is rated at 1.5amp for 110 volt...so it basically equivalent to 165 watts of power consumption...

Comparing AC to DC is apples to oranges....wire gauge can (and IS) smaller because you have a higher voltage to work with...there for same amout of power is produced with less amperage...

So lets go back to my first equations...

20amps @12.6v= 252

20amps @110v=2200

2200/12.6v=174.60317amps to do the same job on a 12.6v system

252/110v=2.290909amps to do the same job on a 110v system....ac or dc....

Ohm's laws are law regardless of what type of voltage you are dealing with....

There are however, many more points you can factor in on differences between AC and DC... but to get the power you need in DC in a car...you have to have the larger size wire....for the home you just really dont run into it...

I have never ran into a house that has only 1 run of 16/2 into a room....if so its for maybe one outlet...but come on...you will almost always have several runs going into a singe breaker (run to each outlet, run to ceiling fans, etc etc)...

Usually the biggest wire you will find in a typical home is 12/3 for electric ranges/ovens, furnances, hot water heaters any major appliance that requires a LOT of power, or dual phase power... other than that most homes are just 14/2, 16/2 ...also depends on codes...

Less amperage on the voltage equals less heat build up on the wire......

 

[McIntosh 10+ year member]

On the amperage is amperage comment....

20amps of draw at 12.6 volt = 252 Watts of power @ 100% efficiency

20amps of draw at 110 volt = 2200 Watts of power @ 100% efficiency

Yes the amperage remains the same but the power output differs... on the back of almost every electronic device ment for use on A/C has a label (UL or whatever) that lists power consumption of the device...

For instance the monitor on this computer is rated at 1.5amp for 110 volt...so it basically equivalent to 165 watts of power consumption...

Comparing AC to DC is apples to oranges....wire gauge can (and IS) smaller because you have a higher voltage to work with...there for same amout of power is produced with less amperage...

So lets go back to my first equations...

20amps @12.6v= 252

20amps @110v=2200

2200/12.6v=174.60317amps to do the same job on a 12.6v system

252/110v=2.290909amps to do the same job on a 110v system....ac or dc....

Ohm's laws are law regardless of what type of voltage you are dealing with....

There are however, many more points you can factor in on differences between AC and DC... but to get the power you need in DC in a car...you have to have the larger size wire....for the home you just really dont run into it...

I have never ran into a house that has only 1 run of 16/2 into a room....if so its for maybe one outlet...but come on...you will almost always have several runs going into a singe breaker (run to each outlet, run to ceiling fans, etc etc)...

Usually the biggest wire you will find in a typical home is 12/3 for electric ranges/ovens, furnances, hot water heaters any major appliance that requires a LOT of power, or dual phase power... other than that most homes are just 14/2, 16/2 ...also depends on codes...

Less amperage on the voltage equals less heat build up on the wire......

Your basic understanding is quite good, to a point. A wire's capacity is an ampere rating, not a power (watt) rating. Yes you can get ten times the power through the same wire at 120 volts versus 12 volts (Ohm's law P=IE). AC to DC is not apples to oranges by any means, the same laws apply. Given a load (amperes), a wire size and a wire length the voltage drop is the same (for all intents and purposes) whether its 12VDC or 480VAC. There is a difference that matters. Losing 2 volts on a 12V system has a tad more impact than losing 2 volts on a 480V system. Combine that with the fact you need ten times the current to achieve the same power level (120V versus 12V) and the required wire size goes up dramatically. I generally don't work residential, mainly commercial and industrial. Electric ranges, dryers and AC are usually #8 or #6 BTW. Nothing smaller than #14 is allowed in a home (#12 for kitchen, bath and dining room circuits). The largest low voltage wire I've had the (dis)pleasure to work with thusfar was 1500kcmil (about 1.5" diameter). High voltage cable is a whole different story. Amps are still amps.

 

[oldschool4me 10+ year member]

to add, some counties will not allow a wire smaller than 12/2 in a home and no two wires can share a hole in the installation either. makes for a fun time drilling x4s lol along with crampy hands from doing pig tails after doing an entire home in 12 wire. code depends on county for the most part but at minimum 14/2 i have never seen 16/2 used. it is not uncommon to see 12v used in home lighting either and maybe only then can smaller than 14/2 be used. im not sure on that.

 

[McIntosh 10+ year member]

to add, some counties will not allow a wire smaller than 12/2 in a home and no two wires can share a hole in the installation either. makes for a fun time drilling x4s lol along with crampy hands from doing pig tails after doing an entire home in 12 wire. code depends on county for the most part but at minimum 14/2 i have never seen 16/2 used. it is not uncommon to see 12v used in home lighting either and maybe only then can smaller than 14/2 be used. im not sure on that.

The National Code allows #14 wire for general purpose (not kitchens, baths or dining room's 20A circuits). Local codes may be more restrictive. Our code is conduit (thank God) so romex isn't an option. Once you feed a low voltage transformer (for under-cabinet lights or whatever) the code doesn't really change. I witnessed a friend's house burn down due to a faulty doorbell transformer. Chit happens.

 

[Canaan 10+ year member]

I can't believe all of you have not figured this out.

140dB @ 40hz is SICKENINGLY LOUD!

On an A-weighted curve!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

A-weighted SPL (dBa) emulates the human ear. Thus, lower freq of a similar acoustic output are read as a lower dBa. C-weighted (aka TL readings) have a much flatter curve. In fact, 140dBa could be as high as 170dBc at some freq!!! The curves intersect at 1000hz.

Read up on SPL weighting before you argue w/ an HT guy //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

Note:

Toxicology major

dBa is used for industrial SPL measurements.

 

[McIntosh 10+ year member]

I can't believe all of you have not figured this out.
140dB @ 40hz is SICKENINGLY LOUD!

On an A-weighted curve!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

A-weighted SPL (dBa) emulates the human ear. Thus, lower freq of a similar acoustic output are read as a lower dBa. C-weighted (aka TL readings) have a much flatter curve. In fact, 140dBa could be as high as 170dBc at some freq!!! The curves intersect at 1000hz.

Read up on SPL weighting before you argue w/ an HT guy //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

Note:

Toxicology major

dBa is used for industrial SPL measurements.

I assume you're implying it would hurt? I had no idea. You mean that guy who has listened at 150+ dB for years is wrong? Say it ain't so. He must be right, he's been to competitions and knows people who can stand it for hours with no hearing loss. Science and physiology don't apply to these men and women from Krypton. I'm no HT guy (not my cup of tea) but I know 125 dB is painful and 150 is fatal to ear tissue. I'm no toxicology major but I know what toxic is. By deduction: their stereos aren't nearly as loud as they claim or they can't possibly listen to them (cranked) for more than a few seconds without permanent hearing loss. Either way I fail to see the point (unless its losing your hearing abilities).

 

[michaelweston]

I don't know why I need 2/0 service entrance into my house, because The wire going to the transformer is only 8 AWG.

 

[McIntosh 10+ year member]

I don't know why I need 2/0 service entrance into my house, because The wire going to the transformer is only 8 AWG.

Utilities are exempt from the code. They most always use aluminum as well.

 

[Innovative:Cory 10+ year member]

Your basic understanding is quite good, to a point. A wire's capacity is an ampere rating, not a power (watt) rating. Yes you can get ten times the power through the same wire at 120 volts versus 12 volts (Ohm's law P=IE). AC to DC is not apples to oranges by any means, the same laws apply. Given a load (amperes), a wire size and a wire length the voltage drop is the same (for all intents and purposes) whether its 12VDC or 480VAC. There is a difference that matters. Losing 2 volts on a 12V system has a tad more impact than losing 2 volts on a 480V system. Combine that with the fact you need ten times the current to achieve the same power level (120V versus 12V) and the required wire size goes up dramatically. I generally don't work residential, mainly commercial and industrial. Electric ranges, dryers and AC are usually #8 or #6 BTW. Nothing smaller than #14 is allowed in a home (#12 for kitchen, bath and dining room circuits). The largest low voltage wire I've had the (dis)pleasure to work with thusfar was 1500kcmil (about 1.5" diameter). High voltage cable is a whole different story. Amps are still amps.

Right...now take a step back and look at something.... amperage is still amperage... but having a increased supply voltage, you are able to do the same amount of power output with less amperage draw... in 12v the wires have to be huge because of the lack of supply voltage...and yes Kirchoff's law comes into place here... more so than it would in a home...

I do apologize for my overall lack of codes for home electrical...its been too long, and I didn't spend much time actually in that field... but learned enough to blow my-self up //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Just stating that in 12v for a 300amp draw you would need a 1/0 wire...(also depends on the distance of the run)....

That would have a potential output of 12.6(300)=3780 @ 100% efficeincy

300 amps on 110.....110(300)=33,000 @ 100% efficeincy....thats a lot of juice... once again...for a 110v aplication I dont know what size wire would have to be used...

But for 12v you might as well just use a solid pice of metal to pass that much power...or 10 runs of 1/0 wire....

I guess what I am saying... to do the same amount of output (power) the wire size will be different from 12v-110v because of the changes in amperage with the increase or decrease in voltages...

200 Watts in a 12v system will need a larger wire than 200 watts in 110v..because the change in amperage, thus a smaller or larger wire is needed depending upon supply voltage....

 

[savagebee 10+ year member]

I assume you're implying it would hurt? I had no idea. You mean that guy who has listened at 150+ dB for years is wrong? Say it ain't so. He must be right, he's been to competitions and knows people who can stand it for hours with no hearing loss. Science and physiology don't apply to these men and women from Krypton. I'm no HT guy (not my cup of tea) but I know 125 dB is painful and 150 is fatal to ear tissue. I'm no toxicology major but I know what toxic is. By deduction: their stereos aren't nearly as loud as they claim or they can't possibly listen to them (cranked) for more than a few seconds without permanent hearing loss. Either way I fail to see the point (unless its losing your hearing abilities).

Your snide comments make me think youre trolling for an arguement, and if you really are a 50 year old professional than I feel sorry for you

The point is the frame of reference for car audio in every competition format would use scores based off of the termlab system (or something similar). Apparently you know that you are doing nothing but arguing sematics, but you continue to do so. Are you just trying to impress people?

 

[Heide264 10+ year member]

I just wanted to put it out there... ever since i started boxing at college I haven't picked nearly as many fights. With the head gear and all its not too bad for ya either... it'll probably benefit ya with the whole cardio exercise idea.

...Just putting the thought out there. It'd be more constructive and enjoyable than this =).