I'm building

my first layout.......no conduit on my feeder wire drops.......2" foam subroadbed, no plywood.....maybe I'm not understanding something here........why the conduit?

Wiring

DSteckler.

If your drop wires are insulated  you don't need tubing , why ad to the cost ,save your money and by more rolling stock

Smokey Dawson   Australia

My first hunch is this might not work very easily unless you

work with rigid, slippery tubing material.  I would suspect aquarium tubing would generate enough friction rubbing against the insulation on the wire to make pulling it something you'd tire of quickly. YMMV though...

Not needed

If the foam is glued solidly to the plywood, you will have no trouble feeding a solid wire through a 3/16" hole, no conduit required. If you are using extra flexible stranded wire, it may be a bit fiddly, but you can make a tool from a piece of 1/8" brass tubing to help stuff it through.

pqe

No need for a conduit, unless

No need for a conduit, unless you want it for ease of feeding the wire through the foam. I would use the smallest drinking straw that your wire would fit through. 

Tim S. - that's exactly what

Tim S. - that's exactly what I was trying to accomplish.  I'll try a drop without a conduit and see how it goes.  Thanks, guys!

Conduit's a good idea!

I've been pondering some of the same problems with my 2" foam: How to get wires through it. A hard-plastic conduit with smooth sides would be best for pulling. Of course, aluminum would also work. Where would you get the aluminum tubing?

Feeder Conduit and Aluminum Tubing

I really don't think you want to install a length of conduit (tubing or straw) through the layout base and roadbed for each and every feeder wire to your track. Even on a small layout that is a lot of tubing. An un-needed expense and a lot of extra work.

If you have very flexible wire and are having trouble getting it through a thick base, the suggestions above about using a piece of straw or tubing to aid in getting the wire run through are excellent ideas. BUT only think in terms of one or two pieces of conduit / guides.

Drill your hole for your conduit / guide and insert it. Pass the wire through. But before you connect the wire to anything, pull the conduit / guide out and over the wire end. Bend the wire over to prevent it from falling back though. Solder the wire to the track.  Reuse the conduit / guide for the next wire.

There was one query in this blog about where to get aluminum tubing. The best source for the size we are thinking about is K&S Precision Metals. Usually in the same LHS display rack as the brass tubing. Sizes are from 1/16" to 9/16" ID.

All that as said and done, my personal method, when I'm having a problem running a wire is to take a small piece of steel or brass wire and make a small hook on the end to pull a wire through a the hole. Think of a Fish-Tape for pulling electrical wire up behind installed walls.

I was think more of . . .

I was think more of installing select feed-points for various wiring projects, mainly structure and other layout lighting accessories, etc. Conduit feed-points, placed every few feet would provide an easy way to feed new wiring as you add new powered accessories to the layout.

Coffee stirrer tubes work great

I sometimes use coffee stirrers to guide wires through thick foam and 1/4 ply. I drill a hole first. Usually I remove the tubes after the wire is through.

Coffee stirrer tubes are great little disposable tools.   You can make a precise applicator for Super Glue. Cut the tube at an angle and slit the sharp point to make a pen nib. Dip the nib into a drop of Super Glue and apply it where needed.

Track Feeders Through 2” Foam

Dropping a wire through foam is pretty easy if you use smaller gauge wire.   My track feeders are 24 gauge wire recovered from CAT-5 cables. CAT-5 has 4 pairs of wires with each pair twisted – a color wire (green, blue, brown,  red) and a white with stripes of the same color.  Each wire is a solid strand. Once the pairs are stripped from the cables, I use a power drill to untwist them.   I’ll work with a four foot length at a time to make it all manageable.  

Having four colors allows some color coding if desired. I’ll usually use the solid color for “inside” rail of the track with the white stripped wire for the other.  That makes it easy to connect the right feeder to the right track buss – solid color wires go to the black buss wire, striped white wires go to the white buss wire.   

To get the wire trough the foam, I create a needle-threader like tool from a small bamboo skewer used as an uncoupling tool.  I’ll drill a small hole in the blunt end of the skewer just big enough for the 24 gauge wire.  I’ll strip a short piece of insulation from the wire and push the wire through the hole and fold it over the outside of the skewer.   I then push the skewer  sharp end first through the foam and pull the wire through.  A a side note, a cute little conical piece of foam pops out of the bottom  end of the hole but I’ve found no useful purpose for them yet.

If you have solid roadbed between the tack and foam, drill a 3/32" hole where you wan the feeder then push the skewer through that.

The 24 gauge wire solders easily to code 83 track without leaving a huge piece of wire visible. After soldering one end of the wire to the track, I’ll cut the other end to length and solder it to my 14 gauge track buss.  

Some folks may be shocked that I use such teeny-tiny wire for track feeders where the more common feeder is 18 or 22 gauge. The feeders tend to be 4-6” long and don’t show a significant voltage drop for a double header HO loco. Your results may vary.    

I have installed dropper wires...

...up to 8" thick using a piece of coat hanger wire. I filed a notch on one end,loop the wire around the notch and just push it through the foam, pull out the coat hanger wire an pull one side of the dropper wire through. It takes longer to read this than to do it! I never bothered drilling holes.

K.I.S.S.

IMO, conduit is usually only really necessary where wires need mechanical protection or where one may wish to pull wires through in the future and will have no access or easy path available.

That said, putting in conduit for every feeder is a good way to count rivets for fun, if that's your idea of fun.

Regards,

Wiring deterioration inside polystyrene foam

This comment is barely applicable to model railroad layouts, but it might be useful to know that in house wiring, placing PVC insulated wiring through polystyrene foam (EPS) can lead to deterioration of the insulation, as the plasticiser slowly migrates out of the PVC into the polystyrene.  (You may have come across the sticky mess it makes.)

I learnt this the hard way after insulating my hobby room with EPS, after the electrical work had been done.  The electrician then insisted on pulling through a new purple coloured cable that is migration-resistant to foam.  Don't know if closed cell polystyrene has the same effect.

Brian M.