On a small layout where no more than ten feet tops, of wire is needed to hook up accessories and track, does it really make a difference if the wire is stranded or solid. I'm talking about 20 gauge wire.
For one thing, solid wire lends itself more to traditional accessories.
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The only advantage for stranded wire is that it is more resistant to damage from frequent flexing. Solid wire is generally cheaper, and entirely satisfactory for your purpose.
I recall once talking to a store clerk about solid vs. stranded wire of the same gauge for automotive applications. He said stranded wire was better because electricity travels on the surface of the wire, and stranded wire has lots more surface area. That's total BS !!!
Ace posted:I recall once talking to a store clerk about solid vs. stranded wire of the same gauge. He said stranded wire was better because electricity travels on the surface of the wire, and stranded wire has lots more surface area. That's total BS !!!
Actually it isn't total BS, it just only applies to very high frequency currents. The effect is meaningless to anything in model trains or general household use, but it does exist.
As far as layout wiring goes, use whichever you prefer. Solid is probably easier to get a clean strip and to attach to things, where as stranded is easier to fish through to the location.
JGL
Ace posted:The only advantage for stranded wire is that it is more resistant to damage from frequent flexing. Solid wire is generally cheaper, and entirely satisfactory for your purpose.
I recall once talking to a store clerk about solid vs. stranded wire of the same gauge. He said stranded wire was better because electricity travels on the surface of the wire, and stranded wire has lots more surface area. That's total BS !!!
Actually it's partially true. But not in this case. It's the omissions of details that were left out. Higher frequency current does travel on the surface of the wire. It's called skin effect.
https://en.wikipedia.org/wiki/Skin_effect
In the case of ordinary stranded wire, the surface area does not increase much since the wires are all shorted together. Stranded Litz wire does have a reduced resistance to higher frequency ac current because all the strands are insulated from each other.
Another sales pitch I heard once was that connectors were gold plated because gold is the best conductor of electricity. Not true. Gold is inferior to copper and copper is inferior to silver. Gold plating is used because it does not corrode. And the plating is only a few atoms thick so not much resistance is added to the connector pins with the gold plating.
JohnGaltLine posted:Ace posted:... a store clerk ... said stranded wire was better because electricity travels on the surface of the wire, and stranded wire has lots more surface area ...
... only applies to very high frequency current ...
cjack posted:Actually it's partially true. But not in this case. It's the omissions of details that were left out. Higher frequency current does travel on the surface of the wire. It's called skin effect.https://en.wikipedia.org/wiki/Skin_effect
In the case of ordinary stranded wire, the surface area does not increase much since the wires are all shorted together. Stranded Litz wire does have a reduced resistance to higher frequency ac current because all the strands are insulated from each other...
That's very interesting. Thanks for the info, guys.
Thanks for all of the replies. A wealth of information to retain.
Stranded or solid, 20 gauge is not close to being adequate for O gauge track power.
Dan Padova posted:On a small layout where no more than ten feet tops, of wire is needed to hook up accessories and track, does it really make a difference if the wire is stranded or solid. I'm talking about 20 gauge wire.
For one thing, solid wire lends itself more to traditional accessories.
20 gauge is too small. Go at least 16 gauge...
Gregg posted:Dan Padova posted:On a small layout where no more than ten feet tops, of wire is needed to hook up accessories and track, does it really make a difference if the wire is stranded or solid. I'm talking about 20 gauge wire.
For one thing, solid wire lends itself more to traditional accessories.
20 gauge is too small. Go at least 16 gauge...
Whoa Nelly, 16 gauge, really ? The wires that are supplied with almost all accessories can't be more than 22 gauge. The longest wire lead won't be any more than ten feet, and that's if I run from one end to the other, which is very unlikely.
Really! Note that I said track power.
People always say "it's a personal preference," but that's silly. Because all my power drops are OGR stranded 14 AWG and had a bad experience with some old brittle solid 22AWG wire, I purposely stuck to stranded for everything. But, I realized brittle old solid isn't a good test case. And, as I've recently discovered, when working with fine wire, like 22AWG and finer, solid is much easier to work with because it doesn't fray or require tinning.
there is one thing about solid wire which you have to watch out for. when you strip the end, make sure you do not nick (even slightly) the wire itself. if you do, it will only a few bends and the single conductor will snap off. for very thin wires (< 26 ga), i use No-Nik strippers exclusively...
cheers...gary
There is no fixed rule for what gauge of wire to use for track power or accessory power. It all depends on the length of wire and how many amps it will carry. A voltage drop calculator (Google it) can be used to figure adequate wire gauge for a specific application.
RJR posted:Stranded or solid, 20 gauge is not close to being adequate for O gauge track power.
i often sit back and smile at these conversations, and i won't offer any counter argument, but if you actually did some practical research on this, 20 ga. wire in open air (how most train layouts are wired), will easily pass 5-6 amps which is a lot more power than any of my trains draw. AWG tables are hugely conservative for maximum power transmission (i.e. usually calculated as bundled wires over km distances) and even pushed to its maximum capacity 20 ga solid copper wire will drop less than a volt for a 10-15 foot run.
i do tend to use 16g stranded just because it is what i have tons of in many colors while lowering the Vdrop to practically zero as long as i keep the runs inside the confines of even large rooms, but after a while i get pretty tired of hearing people claim that you will have major problems if you don't use 12 - 14 gauge wire for even the smallest layouts. 1st off, you're wasting your money and B, i've got news for you that your bottlenecks and major losses are not going to be the wire, but will be in the type and number of connections.
i'm done, so go ahead and trash my comments if you like.
it's still the truth.
cheers, sweetness & light...gary
14 ga solid for track circuits. 18 ga solid thermostat wire for all accessory/switch control.
Layout wiring. Click on the link for a slideshow.
There is some 20 gauge tinned solid copper wire for sale on Evilbay. I suspect the tinning will improve soldering capability.
Be careful of eBay wire. Make sure it's actually solid copper, much of the wire sold on eBay is aluminum that is copper plated.
Ace posted:There is no fixed rule for what gauge of wire to use for track power or accessory power. It all depends on the length of wire and how many amps it will carry. A voltage drop calculator (Google it) can be used to figure adequate wire gauge for a specific application.
Good point. When you look at the charts, multiply the resistance listed by the expected amps on the wire and determine if you can stand the voltage drop. The voltage drop for our low 18 vac circuits are more critical than the 120 vac some of the charts' recommend gauges.
In other words, a 2 vac drop on an 18 vac circuit is more significant than a 2 vac drop on a 120 vac circuit.
Dan Padova posted:Gregg posted:Dan Padova posted:On a small layout where no more than ten feet tops, of wire is needed to hook up accessories and track, does it really make a difference if the wire is stranded or solid. I'm talking about 20 gauge wire.
For one thing, solid wire lends itself more to traditional accessories.
20 gauge is too small. Go at least 16 gauge...
Whoa Nelly, 16 gauge, really ? The wires that are supplied with almost all accessories can't be more than 22 gauge. The longest wire lead won't be any more than ten feet, and that's if I run from one end to the other, which is very unlikely.
I'm thinking about a" short circuit "to either the track or accessory.. 20 gauge in my opinion is just tooo small. I want something that will handle a little more current.
Unless you have very long runs, I'd think that #16 would be sufficient. UL thinks it's good enough to plug into 15A branch circuits for extension cords! 
Obviously, if you run larger wire, you get less voltage drops.
For my track power I did use 14 gauge stranded wire. But for everything else, 14 gauge is too bulky to work with. I did check with the seller on the tinned wire. He assures me that it is tin coated copper. The reason I asked him is that $49.95 for 600 feet of 20 gauge copper wire on six rolls, each a different color, seems like a very good price.
Price is good but in the ball park. Farm and Fleet here sells 18 ga stranded copper, 100 feet rolls for $9 each.
Tin coating is used as a corrosion inhibitor, Even copper when subject to weather and moisture will form oxides and most likely sulfates, blue/green colors, which adds resistance to terminations. Automotive wiring subject to salts and corrosives, would do well to be tin plated, IMO. There are also additives, pastes, that can be use to increase/protect terminations in addition to the plating. Some crimp connectors will have the paste include as part of the connector. A 500 ft roll of single conductor, THHN, 12, 14, 16, or 18 ga copper, either stranded or solid, should be available at a local electrical supply stores. There are also color choices. Surprisingly 500 ft does go far. This forum also has wire for sale. Note that stranded has a slightly larger diameter.
My LHS use 18 for everything so I followed suit. Solid wire is definitely much easier to hook up to accessories. I think 20 should also be fine. This comes from working with BOTH...... (stranded and solid)
A tip for using stranded wire for accessories, just tin the ends so the connections are using "solid" wire, but you have the flexibility of stranded wire. 
I've tinned 24 awg stranded and, because of how thin it is / how few strands there are, I found that it snaps easily. Hence, why I now prefer solid for thin wire needs.
Regarding Fleabay - every seller is obviously different, but I bought wire twice from 2 different sellers and in both cases it was old or poorly stored, brittle and crumbly. Caveat emptor.
Peter
PJB posted:I've tinned 24 awg stranded and, because of how thin it is / how few strands there are, I found that it snaps easily. Hence, why I now prefer solid for thin wire needs.
Regarding Fleabay - every seller is obviously different, but I bought wire twice from 2 different sellers and in both cases it was old or poorly stored, brittle and crumbly. Caveat emptor.
Peter
Any time you tin stranded wire, it is prone to breaking. The auto industry never tins or solders connectors for this reason. They crimp connections. One exception I found were BMW motorcycle harnesses. They bond multiple connection wires of the same circuit together inside a harness but only in a straight run. I think anytime there is movement or vibration, a soldered connector or wire end will tend to break.
Hmm... I have no such issue with tinning the ends of stranded wire, and I've been using that technique for years.
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