Solid or stranded ??

[peteski]

Just an FYI, solid wire in a certain gauge has lower resistance than stranded in the same gauge. 22awg solid does NOT = 22awg stranded. i would suggest going with solid due to the lower resistance. I am a signal construction foreman for BNSF and by rule, we figure stranded at roughly double the resistance for our cable runs. I would at least make your bus wires solid and have larger gauge stranded for the feeders.

Since there is air between the circular-cross-section strands, there is less metal in any stranded wire (compared to the same gauge solid wire), so you are correct. But it is not as drastic as you state.

From http://en.wikipedia.org/wiki/American_wire_gauge
AWG gauges are also used to describe stranded wire. In this case, it describes a wire which is equal in cross-sectional area to the total of all the cross-sectional areas of the individual strands; the gaps between strands are not counted. When made with circular strands (see Circle packing), these gaps occupy about 10% of the wire area, thus requiring a wire about 5% thicker than equivalent solid wire.

Stranded wires are specified with three numbers, the overall AWG size, the number of strands, and the AWG size of a strand. The number of strands and the AWG of a strand are separated by a slash. For example, a 22 AWG 7/30 stranded wire is a 22 AWG wire made from seven strands of 30 AWG wire.

[eja]

BuZZZZZ.. 

Talk about a hijacked thread (solid or stranded)  Thanks to all who contributed an on topic response to my original question.   As usual, you guys and gals are very helpful even if some of do roam off topic !

eja

[peteski]

BuZZZZZ.. 

Talk about a hijacked thread (solid or stranded)  Thanks to all who contributed an on topic response to my original question.   As usual, you guys and gals are very helpful even if some of do roam off topic !

eja

Unfair buzz! We are still talking about solid vs. stranded - just taking it to the Nth level!   

[SkipGear]

Stranded for everything -

I've seen too many solid feeders broken. I built a 4x8 for a gentleman that gave me a bunch of solid core phone line to use for feeders. Never again. I spent more time repairing connections that broke just in the effort of routing wires.

Scotchlock suitcase connectors - NEVER!!! Always solder or use a screw terminal for a connection.

Quite a few years in the car audio industry taught me to hate these vile connectors. Our shop used to make a lot of money repairing the work of other shops (Circuit City and Best Buy at the time) that used scotchlocks. They are unreliable and the connection will eventually corrode. Alarm installs using scotchlocks were the worst. Tracking down random false alarms due to intermittent scotchlock connections is very time consuming.

[mmagliaro]

Stranded for everything -

I've seen too many solid feeders broken. I built a 4x8 for a gentleman that gave me a bunch of solid core phone line to use for feeders. Never again. I spent more time repairing connections that broke just in the effort of routing wires.

Scotchlock suitcase connectors - NEVER!!! Always solder or use a screw terminal for a connection.

Quite a few years in the car audio industry taught me to hate these vile connectors. Our shop used to make a lot of money repairing the work of other shops (Circuit City and Best Buy at the time) that used scotchlocks. They are unreliable and the connection will eventually corrode. Alarm installs using scotchlocks were the worst. Tracking down random false alarms due to intermittent scotchlock connections is very time consuming.

+1 on all counts.
Solid wire in thinner gauges (like 20, 22) breaks too easily, and I hate crimpy/pinchy anything.
Heck, I just threw out a bunch of alligator clip test leads I had bought a few years ago because the crimped connections
of the clips to the wires were starting to measure 0.5 - 1.5 ohms.  It was driving me nuts measuring resistances across
turnout points and rails, where I had a brand new turnout ready to install.  When it didn't read 0 ohms, but the meter read 0
lead-to-lead, I started hunting all over the turnout before I realized it was those crimped  alligator clips.

[C855B]

Hmm. OTOH... commercial connection products abandoned soldering decades ago in favor of mechanical crimping. A properly-executed crimp connection runs rings around soldering in both consistency and long-term reliability. "Properly-executed", however, doesn't mean a typical DIY field crimp with a pair of pliers, it usually means a dedicated tool for the connector system.

Anyway, I'll join the chorus against ScotchLok taps - easy, but not for something you want to last, and definitely not for situations that see humidity. For impromptu in-line connections I'll typically cut the main lead and use barrel butt crimps with, again, a proper crimping tool.

That said, for certain crimping types like what Max mentioned with his alligator clips, those aren't designed for crimp tools, so we're back to hoping for the best with a pair of needlenose. I crimp and solder those, absolutely.

[Blazeman]

Yet that magazine we love to critique here continues to to extol the virtues of the connectors. This thread and assembly of talent and info isn't the only place that I've heard caution on using those items.

[peteski]

I have also  read (from many sources) that crimped connections are more reliable than soldered connections.  To me it is counter intuitive, but I have noting to disprove those claims.  But I winder if those studies were done by ... the crimp connector manufacturers! 

However I don't know if any of you realize that every computer out there, and most consumer electronic devices have many (or all of its internal wiring attached to the connectors) using IDCs (insulation displacement type of connectors). They work like the suitcase connectors - puncture through the wire insulation and pinch the stranded conductor.  For example, all the ribbon cables in your computer have IDC connectors on them. How often have you seen them fail (especially considering that each connector has 100 or more connections in them)?

To me a well made solder joint seems to be much more reliable than any mechanical connection relying on pressure between 2 parts.  However I also thin that properly made (that is the important part) crimp connections or properly tightened screw terminals are more than adequate for model railroad wiring.  The screw terminals have been extensively used in all sorts of electrical equipment for a very long time, and they are still being used (especially in power supplies).  If they were not reliable, they would have been abandoned.

Unless exposed to a constant high-frequency vibration, screw terminals are quite reliable.  If properly tightened, under the layout, they will never experience the type of prolonged vibrations which could loosen them.

Corrosion can be a factor. But that is true with solder joints too.  The industry has a solution for that too. Phone line splices are often filled with a clear grease(vaseline?) to protect the exposed metal from corrosion.   Special grease is also used for crimp joints on aluminum wiring.  If someone is really worried about corrosion in their crimps, the could apply some vaseline to the wire before crimping it in the terminal.

[Sokramiketes]

That clear stuff is most likely dielectric grease.  It's meant to be displaced when the mechanical connection is made and keep out air so corrosion is inhibited.

I figure shrink wrap does a pretty good job at sealing out the air as well. 

[alhoop]

From the reading here I don't see how the phone companies survived with their extensive use of solid wire.

Al

[peteski]

That clear stuff is most likely dielectric grease.  It's meant to be displaced when the mechanical connection is made and keep out air so corrosion is inhibited.

Exactly. But what really is dielectric grease? Vaseline (petroleum jelly)?

Phone company  has been using solid copper wire and non-soldered connections for well over 100 years. I also don't know how they managed to keep things working for over a century! 

[mionerr]

Exactly. But what really is dielectric grease? Vaseline (petroleum jelly)?

Phone company  has been using solid copper wire and non-soldered connections for well over 100 years. I also don't know how they managed to keep things working for over a century! 

And the connections are on "punch down" blocks which are a form of IDC. Been working for years and is STILL used.

[DKS]

But what really is dielectric grease? Vaseline (petroleum jelly)?

No, it's silicone grease.

[SkipGear]

I have also  read (from many sources) that crimped connections are more reliable than soldered connections.  To me it is counter intuitive, but I have noting to disprove those claims.  But I winder if those studies were done by ... the crimp connector manufacturers! 

However I don't know if any of you realize that every computer out there, and most consumer electronic devices have many (or all of its internal wiring attached to the connectors) using IDCs (insulation displacement type of connectors). They work like the suitcase connectors - puncture through the wire insulation and pinch the stranded conductor.  For example, all the ribbon cables in your computer have IDC connectors on them. How often have you seen them fail (especially considering that each connector has 100 or more connections in them)?

To me a well made solder joint seems to be much more reliable than any mechanical connection relying on pressure between 2 parts.  However I also thin that properly made (that is the important part) crimp connections or properly tightened screw terminals are more than adequate for model railroad wiring.  The screw terminals have been extensively used in all sorts of electrical equipment for a very long time, and they are still being used (especially in power supplies).  If they were not reliable, they would have been abandoned.

Unless exposed to a constant high-frequency vibration, screw terminals are quite reliable.  If properly tightened, under the layout, they will never experience the type of prolonged vibrations which could loosen them.

Corrosion can be a factor. But that is true with solder joints too.  The industry has a solution for that too. Phone line splices are often filled with a clear grease(vaseline?) to protect the exposed metal from corrosion.   Special grease is also used for crimp joints on aluminum wiring.  If someone is really worried about corrosion in their crimps, the could apply some vaseline to the wire before crimping it in the terminal.

As far as friction connections in a computer application, there are a lot of factors working for them......

#1  The wires in a computer generally don't move. Not much chance to wiggle a connection loose.
#2  The voltage and current demands are much lower than anything we use.
#3  Matched plug and wire combinations, designed to work together.
#4  If there is enough moisture to create corrision in a computer, crimp connections are the least of your worries.

My other hobby is electric RC cars and planes. I have batteries that can supply over 400 amps and move an 8 lb rc car at 50+ mph. Connectors and connections are very important to me. There is no crimp connection that can handle the abuse I can put them through. For many years we direct soldered our batteries in the cars because nobody made a connector that could hold up to the abuse. Now with Lithium Polymer batteries, plugs are a must as the batteries have aluminum tabs coming out of the individual cells that can't be soldered too easily and too much heat would damage the battery. The common connectors we use can handle 100A + and must be soldered. We typically use 12 gauge silicone jacketed wire with 1660 strands for connections. This also the wire I am using for my bus on my layout, just because I have lots of it around. Probably a bit of overkill but I have it.

Our trains will never pull that kind of current and put that much demand on a connector but I would rather be safe and use a little overkill when it comes to connections. Climbing under a finished layout, searching for a loose connection does not appeal to me.

My source of wire and some of the connectors I use... http://wsdeans.com/products/wire/index.html
I am using some of their 4 pin gold plated connectors as interconnects between the yard moduled on our Ntrak layout. I still can't believe Cinch-Jones (sp?) connectors were the standard for so long.

[peteski]

My source of wire and some of the connectors I use... http://wsdeans.com/products/wire/index.html
I am using some of their 4 pin gold plated connectors as interconnects between the yard moduled on our Ntrak layout. I still can't believe Cinch-Jones (sp?) connectors were the standard for so long.

Cinch-Jones connectors were solder-only. However the new N-Trak standard PowerPole connectors are really designed to be crimped (yeah, some people solder them).