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Stranded or Solid wire?

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  • Member since
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  • From: Kansas
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Stranded or Solid wire?
Posted by jamnest on Friday, May 23, 2008 1:36 PM

I am constructing a large (30'x60') HO scale walk-around layout in my basemnt. The layout is being built from modular (domino) sections.  I have a Digitrax Super Chief (radio), with two DB150 boosters. My command station & power supply is in a central location with protected 20 AMP electrical service.  I have had my Digitrax system for ten years and had it running a similar size layout in my previous home.

From the power supply/command station I have run 12ga solid coper wire (about 50 feet) to the layout.  My layout bus wire is 12ga stranded copper wire as it was less expensive to buy 500 ft spools of red and black contractor wire at Lowes.

I have been using 18ga solid coper wire for my jumpers to each soldered section of track.  I use red and black wire.  Solid 18ga wire has been difficult to find so I have also used 18ga stranded wire.  I use trminal strips and "suitcase connectors" to attach the jumpers to the buss wire.

I have good track voltage and DCC signal.  I have heard arguments/opinions both ways for using solid versus stranded wire.  Both types of wire appear to work fine and I am using what I can get.  I am , however starting to wire a large layout and would like to get some feedback on the subject before I get too far along with this project.

I would like to hear some opinions on the issue.

Jim, Modeling the Kansas City Southern Lines in HO scale.

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Posted by Trynn_Allen2 on Friday, May 23, 2008 2:00 PM

Stranded all around is going to give you more flexibity in a rapidly changing climate (if the layout is in a garage or a poorly insulated home or basement), Stranded is also going to have less resistence and more carrying capacity than solid.

I got rid of suitcase connectors and terminal strips a long time ago.  They are just one more bad connection waiting to go wrong.  A well made plug and soldered connections with electrical tape are far better and more sure connectors for the layout.

I find solid good for lighting structures or for very very short runs, but after using it on the layout for a bit I disgarded what I have.

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Posted by jeffrey-wimberly on Friday, May 23, 2008 2:35 PM
Use stranded wire and avoid suitcase/crimp-on connectors. Solder the connections and wrap with electrical tape.

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Posted by Vail and Southwestern RR on Friday, May 23, 2008 2:36 PM

Stranded and solid wire of the same gauge have the same current carrying capability.  It pretty much comes down to which one is easier for you to use.  Using the IDC connectors, I would be tempted to stick with solid, since I think there is less chance of damaging the wire that way.  I don't think you need to use 18 gauge for feeders, doorbell wire (20 maybe 22, I think) would work fine.

As far as the suitcase connectors, my opinio is that when they are applied correctly to the wire size they are designed to handle, they should work fine, for a good long time.  The one possible exception being in a very damp environment.  I think some people apply them incorrectly, using the cover to drive the blade through the wire.  In fact, this was demonstrated in the Dream Plan Build DCC video incorrectly.  When done this way, or with the wrong size wire, I am not surprised by failures.

Jeff But it's a dry heat!

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Posted by tomikawaTT on Friday, May 23, 2008 2:52 PM

If the wire is solidly, immovably, anchored and unlikely to be bent after installation, use solid.  If there is any need for a flexible connection, use stranded.

I don't use suitcase connectors, since I have reservations about their long-term reliability.

That said, I personally use solid wire for anything that doesn't get flexed on a regular basis.  I also use terminal strips - the ability to break circuits when troubleshooting far outweighs the (to me, nonexistent) possibility of developing an open circuit.  Some of my wiring has been in continuous, trouble-free service since 1980, so I must be doing something right.

Chuck (modeling Central Japan in September, 1964)

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Posted by selector on Friday, May 23, 2008 3:32 PM

A braided wire of multiple strands is necessarily going to have gaps at points spiralling along with the strands.  So, in cross section, it would seem to me that the solid wire of a given gauge should get the nod in terms of overall retention of voltage because its cross-section is uniform along its length.  If you place three 12 gauge wires tight alongside each other, nestled, you will see a gap when you hold them edge-on because they can't meet in the middle due to their round profiles.  This happens on a smaller scale several times in the small braided wire we are talking about.  That missing profile doesn't exist in the solid wire.

My My 2 cents [2c].  Perhaps an electrical engineer will be able to clear it up for us?

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Posted by Vail and Southwestern RR on Friday, May 23, 2008 3:49 PM
 selector wrote:

A braided wire of multiple strands is necessarily going to have gaps at points spiralling along with the strands.  So, in cross section, it would seem to me that the solid wire of a given gauge should get the nod in terms of overall retention of voltage because its cross-section is uniform along its length.  If you place three 12 gauge wires tight alongside each other, nestled, you will see a gap when you hold them edge-on because they can't meet in the middle due to their round profiles.  This happens on a smaller scale several times in the small braided wire we are talking about.  That missing profile doesn't exist in the solid wire.

My My 2 cents [2c].  Perhaps an electrical engineer will be able to clear it up for us?

One already did!

The key is that the gauge of the wire is determined by the total cross section of the conductors, 12 gauge solid and 12 gauge stranded have the same cross section of conductors, and can carry the same current.  At high fequencies, things can get different, but that's not an issue for DCC.

Jeff But it's a dry heat!

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Posted by larak on Friday, May 23, 2008 10:58 PM
 Vail and Southwestern RR wrote:
 selector wrote:

My My 2 cents [2c].  Perhaps an electrical engineer will be able to clear it up for us?

One already did!

The key is that the gauge of the wire is determined by the total cross section of the conductors, 12 gauge solid and 12 gauge stranded have the same cross section of conductors, and can carry the same current.  At high fequencies*, things can get different, but that's not an issue for DCC.

Make that two.  

Solid, stranded - both work just fine. Stranded is more flexible, solid wraps around screws more easily. As for scotchlock connectors, (note the specific brand) they work well too when properly applied. However, I wouldn't use them in damp or corrosive areas either.

*Ooh ... skin effect. Maybe we should start a rumor that Litz wire is better then either of them when using DCC? 

 

The mind is like a parachute. It works better when it's open.  www.stremy.net

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Posted by UpNorth on Friday, May 23, 2008 11:18 PM
American wire gauge tables do not call out a differrence in current carrying between stranded and/or solid for the same gauge. They treat it as one and the same.  It is a question of flexibility and which is less likely to break.  Solid for drops is quite enough as you have one strand to solder properly to the side of the rail.  Just don't bend it over and over.
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Posted by Driline on Saturday, May 24, 2008 12:15 PM
 selector wrote:

A braided wire of multiple strands is necessarily going to have gaps at points spiralling along with the strands.  So, in cross section, it would seem to me that the solid wire of a given gauge should get the nod in terms of overall retention of voltage because its cross-section is uniform along its length.  If you place three 12 gauge wires tight alongside each other, nestled, you will see a gap when you hold them edge-on because they can't meet in the middle due to their round profiles.  This happens on a smaller scale several times in the small braided wire we are talking about.  That missing profile doesn't exist in the solid wire.

My My 2 cents [2c].  Perhaps an electrical engineer will be able to clear it up for us?

You're splitting strands....err hairs here. As an electronic technician for some 20 years both are equal. Like the other electronic engineers here have alluded to, use what is cheaper and or available in your area. We use mostly stranded wire in television broadcasting because its much easier to manipulate.(I'm talking audio here, video is another thing).

Modeling the Davenport Rock Island & Northwestern 1995 in HO
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Posted by selector on Saturday, May 24, 2008 1:04 PM

Okay, fellas, thanks for setting me straight.  I have learned something to file away. Smile [:)]

-Crandell

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Posted by jackn2mpu on Saturday, May 24, 2008 4:41 PM

One thing nobody mentioned is stripping the wire. If you use the wrong stripper, or something like a knife blade, you run the risk of losing strands of wire and ending up with thinner wire. Couple that with suitcase connectors and you have a recipe for all kinds of gremlins that you'll pull your hair out trying to find. Same goes for soild wire - use a knife blade to strip or the wrong size stripper and you'll nick the wire, making for an eventual break in the wire totally losing the electrical path.

Retired (unwillingly) electronics engineer/technician who was NASA certified for wiring spacecraft. 

de N2MPU Jack

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Modeling the NYC/NYNH&H in HO and CPRail/D&H in N

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Posted by modelmaker51 on Saturday, May 24, 2008 7:00 PM
I always tin the ends of stranded wires (and then bend them) when attaching them to terminal strips.

Jay 

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Posted by BR60103 on Saturday, May 24, 2008 9:57 PM

Not mentioned yet is that stranded wire is a larger diameter than solid wire of the same gauge. If you have a wire stripper with different holes marked with the gauges, you may need to use the next larger size for stranded wire (some of the new ones are marked for both solid and standed).

As far as I am concerned: stranded where the wire will be flexed a lot, solid if you need it to keep a shape,  either in any other situation. Solid may have an edge if you have to put it in pins and sockets.

 

--David

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