OK, that is probably a really dumb question, but all I want to know is if there is something different about 16 AWG speaker wire that would prevent it from being used to handle 2 amps @ 12 volts DC.
The reason I am asking is that I can buy the speaker wire in bulk for about 1/3rd the cost of similar 22 AWG wire.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
Well sure, in fact why would you use thinner #22 when the heavier #16 is cheaper? Just have to pay more attention with most speaker wire to get the polarity consistent, usually it's identified either by one of the wires being tinned, so it looks silver compared to the copper of the other conductor, or there are ribs in the insulation of one side and the other side is smooth.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Pet the following table, the 22AWG is good for 7 amps and the 16AWG for 22 amps DC.
http://www.powerstream.com/Wire_Size.htm
Paul
Modeling HO with a transition era UP bent
peahrens Pet the following table, the 22AWG is good for 7 amps and the 16AWG for 22 amps DC. http://www.powerstream.com/Wire_Size.htm
Ugh, please do not use that chart. Here is a good reference.
http://www.engineeringtoolbox.com/wire-gauges-d_419.html
http://www.engineeringtoolbox.com/amps-wire-gauge-d_730.html
CG
peahrenshttp://www.powerstream.com/Wire_Size.htm
CentralGulfhttp://www.engineeringtoolbox.com/wire-gauges-d_419.html
Every time this question comes up, these two tables are provided as responses. I have never understood why they are different although I tend to trust the second one because it matches the 14 ga for 15 amp and 12 ga for 20 amp that I've heard for 50 years.
Can somebody explain the difference between the two?
I have the right to remain silent. By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.
They are just presenting the information in different ways. Though the one Paul posted vs the first one CG posted have VASTLY different numbers for the ohms per 1000 ft of each wire size. I've always used the number in Paul's to calculate voltage drop. The second one posted by CG shows the maximum current per size of wire over a given distance for no more than a .36 volt drop. ANythign less than a .5v drop is good, much more and if it's track power, you will see a speed difference.
rrinkerThough the one Paul posted vs the first one CG posted have VASTLY different numbers for the ohms per 1000 ft of each wire size.
CG's is ohm's per 1000 meters.
Missed that, the dimensions to either side of that in Paul's table are in SI units. So they do agree if you account for the meters vs feet. Bottom line - both tables are the same and just present different bits of information.
There are two capacities for wire, really - in free air (bare copper) and enclosed or insulated. There's a MAXIMUM current it can handle (no regard for voltage drop, just how much can you pull before the wire melts) which really has no meaning for any of our applications. There's a rule of thumb/electrical code requirement of #14 for 15 amp circuits and #12 for 20 amps but that also has no application here, that is also assuming starting with 120 or 240V and if you run the calculations that's actually quite a significant voltage drop at those current levels but since you start with 120V it's not such a big deal if it drops down to 110. But 12V dropping to 11V will make a noticeable difference in loco speed, so you can't say since #14 is used for 15 amp household circuits it's good for 15 amp DCC bus lines. It will safely handle 15 amps without setting anything on fire, true.
hon30critterThe reason I am asking is that I can buy the speaker wire in bulk for about 1/3rd the cost of similar 22 AWG wire.
I haven't shopped for wire lately, Dave, but you might want to check out old fashioned zip cord for cost comparison, too. I remember when I was wiring some speakers at home and the zip cord was less expensive than speaker wire at the time.
https://www.google.com/?gws_rd=ssl#q=zip+cord+wire
Have Fun! Ed
rrinkerBottom line - both tables are the same and just present different bits of information.
It is the numbers for current capacity that are confusing. Powerstream says max amps for power transmission for 12 ga is 9.3 - Engineering Toolbox says 20.
Read the definitions for the categories on each site. Powerstream uses a rule of thumb of 700 circular mils per amp. #12 is about .0808 diameter, or 80.8 mils, circular mils = diameter squared so about 6528 circular mils / 700 = 9.3 amps. It is (and they say so) a very very conservative number. It's more accurate for larger wire, less so for smaller - compare #1 wire, Powerstream 110 amps, the other site 119.
Engineering Toolbox sets the conditions as PVC insulation, up to 1000 volts and up to 30 degrees C ambient. Change any of those and the humber changes.
Also note that the numbers everyone is quoting from Engineering Toolbox is for up to 3 conductors - IE you typical house wiring. Things like my DCC bus are individual strands THHN so the maximum current is actually higher.
And right back to it - for low voltages, like 12-15V track power, that maximum current number is meaningless. Let's say we have 50 feet between source and load. That's 100 feet of wire. At 10 amps, with #13 wire (half the rated max), at 120V input, it's a 1.36% voltage drop - not much. Still over 118V at the load Change the input to 12V and it's a 13.6% voltage drop - almost down to 10V. Somethine meant for 120V getting 118V will be fine. Something made for 12V getting 10V is going to be noticeable slower. Or dimmer, in the case of LED strips.
And the REAL bottom line - #16 is FINE for 2 amps worth of LED strips, for 20-25 feet anyway. And infinitely better than #22.
Thanks everybody,
I have shopped around and the 16 AWG speaker wire is the best deal I have found north of the border.
I actually looks exactly like red/black zip wire.
Power loading on the wire will not be an issue. The 18 amp @12 volt / 9 channel CCTV power supplies I bought will handle a maximum of 2 amps per channel. I have divided my LED strip lighting which is rated @ 1 amp/meter into 1.6 meter lengths or less. Each channel will have a 1.6 amp @ 12 volt load vs 2 amp max. Each channel is fused seperately. The longest run might be 35' tops including the LED strip. It sounds like a lot of wiring but in fact there will only be a total of 27 circuits (3 power supplies).
[quote user="hon30critter"]
I be concerned about the insulation value. Not all are created equal, hence your cheaper price. Best to contact the manufacturer and get a cut sheet.
Chuck B. DrayerI be concerned about the insulation value. Not all are created equal, hence your cheaper price. Best to contact the manufacturer and get a cut sheet.
Hi Chuck,
Welcome to the forums!!
Thanks for your advice. Since I asked the question (a couple of years ago) I have given up on building my own layout. My back has gone south big time. I can no longer carry a sheet of plywood and it would be impossible for me to get underneath a layout to do the wiring. Even standing for more than a few minutes these days is painful. 'My' layout will be at the club. I was lucky enough to have my design chosen for our new layout. Construction started about 1 1/2 years ago and we are well along the way.
If you are interested in seeing the club's layout there is a rather long thread here:
http://cs.trains.com/mrr/f/11/t/263414.aspx
Cheers!!
Wow, I did a lot of math in this thread. LOL
Yes, the insulation is a concern - you can get speaker wire in all sizes, even ones that match the size of wire used for wiring your household electrical system. But #12 speaker wire cannot be substituted for #12 ROmex when wiring your house, the speaker wire inuslation is not made to handle 120/240VAC, and the typical stuff, if tun between floors of your hosue, would probably act like a fuse (fireworks type, not electrical) and help spread a fire. You have to be careful when running networkign cables in your house too - there is teflon insulated network cable (cat 5 ethernet and so forth) which is "plenum rated" which means it can be used in the typical open return air spaces above the ceiling in commercial building because it doesn't readily conduct flames along its length, potentially bypassing fire walls and other safety measures.
Hi Randy,
Thanks, that is good information.