The reason that I am skeptical about the need for stranded wire is that it is electrically virtually identical to solid wire. A stranded wire of a particular gauge has the same cross-section of copper as a solid wire of the same gauge. You would think it would be larger in overall size because of the air spaces between the strands. It is, but only very slightly, since stranded wire is customarily squeezed after stranding, reshaping the strands and filling much of the space between them. Since the strands are in intimate electrical contact, a stranded wire is much like a slightly larger wire made from slightly more resistive metal, whose conductivity is the net result of the copper and what remains of the voids.
Skin effect is a real phenomenon which increases the effective resistance of a conductor by concentrating the current in the outer part of the conductor. It is indeed negligible at power-line frequency. At whatever the (apparently secret) DCS frequency is, skin effect might come into play. However, the skin depth increases as the square-root of the resistivity. So the proportion affected by the phenomenon of the diameter, which also increases as the square-root of the resistivity, remains the same. Thus the effect of the very slight resistivity and diameter increase due to stranding would be very hard to detect at all.
There is a special kind of stranded wire--Litz wire--made of individually insulated strands woven in a special pattern that has all the strands meandering between the inside and the outside of the bundle. This is effective in thwarting the skin effect; but it is a very different thing from ordinary stranded wire. I suspect that much of the halo around stranded wire comes from a confusion between the two kinds of stranding.
Do I understand correctly that Mr. Haislip redid his wiring with a different geometry and with stranded wire replacing solid wire? And that he then attributed the improvement as much to the stranded wire as to the geometry change? If so, you can see the fallacy.
The purpose of stranded wire, I believe, is entirely mechanical--It's easier to work with.
Bob Nelson
ChiefEagles wrote:As far as wiring, should have none if you have a good ground. TMCC and TMCC II work on radio signals. I have all "homerun" wiring on the new layout and TMCC does great. DCS uses the track to send signals.
Chief,
You raise a good point there. I'm planning on running a new wire from a new circuit directly from my breaker box to exclusively power my ZW and any other transfomers I need for the layout. This way I insure a ground for TMCCII instead of guessing on wiring from 50 years ago. Old houses are a royal pain. Once it's all hooked up I'll report back on any signal problems. I'm expecting some kind of gremlin when trains run through that 8' metal bridge of mine unless I ground it as well.
Bruce Webster
God bless TCA 05-58541 Benefactor Member of the NRA, Member of the American Legion, Retired Boss Hog of Roseyville , KC&D Qualified
I have that video too. It was very influential when I was deciding which Command Control system to go with (rolling eyes here ). I wired my layout with #16 gauge stranded using home runs as per the DCS recommendations....then did a complete 180 and purchased TMCCII. LOL How much you wanna bet I have signal problems with TMCCII?
Luther,
Although I don't fully understand the properties of electricity, I'm learning. I think I even understand what you say about the halo of electrons around the outside of the wire. Maybe DCS electrons aren't as dumb as others suspect. .
Mr.Haislip had signal problems on the second wiring of his layout when he used solid wire and the home run method of wiring. Imagine having to rewire a third time? Argh! He doesn't go into detail describing why there was a signal loss but I can bet his somewhat complicated medium size layout also had something to do with it as well. People with smaller layouts might not have issues with DCS and solid wire.
OK,
I thought I was dreaming for a bit there. I found the article on "DCS Wiring Tips" in CTT not OGR, the July, 05 issue. Jamie Haislip is the author and is subtitled "Adding MTH's control system to medium and large layouts". For quick reference you can turn to page 67 and read the section titled "Types of wire". Elsewhere in the article Mr. haislip states that MTH itself recommends using stranded wire. To quote Mr. Haislip " The first time I rewired my layout for DCS I used a standard twisted no.14 solid wire and had disasterous results - the signal loss was worse than with my original grid wire".
Hope this helps somebody avoid a costly and agrivating rework in the future.
My above post assumes that the wire in question in fact carries the DCS signal.
That leads to an interesting question as I have never investigated DCS (only running TMCC). How is the DCS signal transmitted? I doubt it runs over the power bus.
Thanks,
Luther
Buckeye Riveter wrote: lionelsoni wrote:I can't imagine how stranded wire would make DCS work better.I don't know as much about electricity as Bob , but I don't think electrons take classes so they can tell the difference between stranded and solid. (If any of you electrons out there have taken classes, I'm sorry if I offended you.)
lionelsoni wrote:I can't imagine how stranded wire would make DCS work better.
I don't know as much about electricity as Bob , but I don't think electrons take classes so they can tell the difference between stranded and solid.
(If any of you electrons out there have taken classes, I'm sorry if I offended you.)
OK, I am going out on a limb here as it has been a while since the engineering classes, but there is a phenomenon known as skin effect. This is the tendency for the electrons to travel on the outside of a wire as opposed to the inside. I believe that this effect increases as the frequency of the signal increases, so perhaps at 60Hz the skin effect is minimized.
However, if this effect has enough of a presence at 60Hz and the surface area presented by the individual strands of wire is greater than the surface area presented by the solid wire (have not verified this), would it not logically follow that you would conceivably have a stronger signal with the stranded wire, and hence better DCS performance with stranded wire than solid?
As I said - this is just a theory - I have not proven any of this mathematically or otherwise. Just some food for thought -- and what are your thoughts?
You might check the prices at an electrical supply company called "Rexel". They have a few stores in Baltimore.
You will be able to purchase larger spools of stranded or solid core wire in various colors.
Chris
Guys,
In the recent past OGR had a 2 part article on DCS in general ( I will dig these out and post what issues they were in later). As I recall the author had no end of troubles trying to make DCS work using the bus wiring and solid core wire that already existed on his layout. His ultimate fix was to rewire the entire layout with straight runs and stranded core wire. I can't explain the reasons why this works better but I do remember the authors insistance in doing it this way. I just reads 'em...I can't respond from personal experience.
Still waiting rather impatiently for my TMCCII order
Celebrating 18 years on the CTT Forum.
Buckeye Riveter......... OTTS Charter Member, a Roseyville Raider and a member of the CTT Forum since 2004..
Jelloway Creek, OH - ELV 1,100 - Home of the Baltimore, Ohio & Wabash RR
TCA 09-64284
88,
Aside from gauge, what's equally important is the method in which you wire your layout. Bus wiring works fine for conventional or TMCC systems but straight run wiring is best for DCS. DCS also works better using stranded instead of solid core wire. Decide which system you intend to stick with then wire accordingly.
It does depend on what you are running but a lot easier to do it right the first time. You can go to Home Depot etc and get a 500ft spool for $60-70.
I am using 12 awg stranded. At times, I will be running two passanger trains on the same mainline.
There are two considerations:
You should use wire heavy enough to carry the greatest current that your transformer can put out. Many large transformers, like the Z and ZW, can put out as much as 15 amperes before the circuit breaker trips. This requires 14 AWG to be safe. If you have a smaller transformer and know what its circuit breaker rating is, you can safely use wire sized for that current. But keep in mind that you may get a bigger transformer some day and won't want to have to rewire your layout.
If you have enough track (or enough poor track joints) to warrant them, you should use heavy wire for feeders. The track itself is no better than the equivalent of about 16 AWG; so there is not much point in feeders that small. Ergo, 14 AWG or larger for feeders. (I would use at least 12 AWG.)
That "speaker wire" is priced to exploit audio fanatics. You can get much cheaper wire at any "home improvement" store (Home Depot, Lowes). The cheapest is non-metallic sheathed cable ("Romex"). You can also get individual solid and stranded wire in a variety of colors by the foot.
Many of the electical minds here recommend 14AWG wire for connecting power lines...Would this work or is it overkill? Any other recommendations for where to get 14AWG wire?http://www.impactacoustics.com/product.asp?cat%5Fid=3104&sku=43089
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