DCC Wiring Question - Twisted Pair

[BN_Railfan]

My club is in the process of rewiring our Digitrax controlled layout and we are in the process of installing several PM42 boards, new main bus wiring and track feeders.

I have started to install new bus wiring using "twisted pair" wiring, which I create by pairing two different coloured wires into a cordless drill and running the drill to twist the wires together along their length. The problem is that when I release the wiring from the drill, it wants to go back to it's original condition, which was straight. Typical bus wire length is six to eight feet due to the size of the club layout.

Anyone have any ideas on how to maintain the "twist" while pulling the wiring into the benchwork under the layout? I would prefer not to use zip ties along the length of the bus wire as the holes we've drilled in the benchwork are really only large enough for the wiring. I'm also tempted to try wraps of electrical tape every foot or so - just wondering if anyone on the board has experience with this.

In case you're curious we are using the twisted pair method for two reasons - first to reduce the possibility of any electrical signal interference but more importantly so that we can run similar colours in close proximity to one another but still be able to easily differentiate which block they are connected to.

 

[santafewillie]

How about fastening the wires at one end, running them and then twisting. Hold them until you can fasten them at the other end. That is if there's enough room.
willie

 

[fcwilt]

If you use solid wire then it should remain twisted - it does for me. I wouldn't expect stranded to stay twisted.

One aspect of twisting is that you are increasing the capacitive load on the source - which can be good or bad depending on how the source reacts.

 

[Selector]

Why are you twisting the bus wires? Is is so long, say 60' or longer, that you want to avoid interference of signals? And must it be essentially braided, or twisted as a hemp rope's filaments are first twisted prior to braiding? I would think eight to ten wraps over 80 feet should be lots.

 

[Iron Horseman]

I have started to install new bus wiring using "twisted pair" wiring, which I create by pairing two different coloured wires into a cordless drill and running the drill to twist the wires together along their length. The problem is that when I release the wiring from the drill, it wants to go back to it's original condition, which was straight. Typical bus wire length is six to eight feet due to the size of the club layout.

That is mighty short runs to require twisting. The museum that I work at twists the bus wires but they are up to 100 feet long.

BUT to your main question. Is the wire stranded? If so are you twisting it in synch with the twisting of the strands of wire? Also how are you unspooling the wire. If you run the wire straight off the edge (unrolling so to speak) the effect will be different than if you unwind it over the top of the spool. Unwinding over the top puts a a natural twist into the wire. Unfortunately most spools are wound the same direction so they still don't want to twist together. In that case the entire strand needs to be flipped end to end and there will be a natural tendency to twist together.

Short answer is, the first thing to try it to twist it in the opposite direction.

 

[Nucular]

I never understood why people hide the wires on the train layouts. Why not instead run the wires overhead and simulate real life electrical wires? Actually run them from pole to pole, and make it add to the scenery.

 

[hunslet040]

Grip the pairs of wires tightly in a vice and the other end in your cordless dril and then twist as usual.
Then when the required twist is done pull the drill to stretch the twisted wires and the twist will stay.
Used this technique during 15 years of Industrial Fieldbus wiring where twisted pairs were often required inside cabinets. Give it a try.
Hope this helps.
Regards, Colin.

 

[NScaler]

I never understood why people hide the wires on the train layouts. Why not instead run the wires overhead and simulate real life electrical wires? Actually run them from pole to pole, and make it add to the scenery.

I think its because you don't want to have to reach through a bunch of telephone pole wiring to get to the trains or scenery items.

 

[Iron Horseman]

I never understood why people hide the wires on the train layouts. Why not instead run the wires overhead and simulate real life electrical wires? Actually run them from pole to pole, and make it add to the scenery.

I hope your joking. But, if not, the scale size wires would melt down from the current they would have to carry.