Isolated Rail Information John Kerklo November 03, 2003

At Sunday's meeting, I had questions about rail isolating pins, fish paper, and male disconnect terminals for rail connections. Thought the following might be a useful "Tidbits" subject.

Rail isolating pins are nylon/plastic pins for joining rails without making an electrical connection. Standard item for O or O27 gauge track (get the right size). Typically found in the rails of O22 switches that provide for non-derailing. Generally available from train sources, including Mizell's and Caboose locally.

Fish paper is broadly used for electrical insulation. It is known as "Fish Paper," "Fyberoid Fish Paper," "Natural Hard Fiber," and "Vulcanized Fiber." A .010 inch thickness seems to work well for isolating high-rail track rails. We use a piece a little smaller than 3/4" x 3/4" for O gauge. It needs to cover the metal tie and clamps, but not interfere with wheel flanges on the inside of the rail.

Mouser carries a tightly-rolled (inconvenient) sheet 10" by 24" which can make about 400 rail insulators. It is Mouser part number 524-560, $4.05/sheet. It carries a label "GC Electronics, Fiberoid Fish Paper, .010 inch thick, #560. We cut it into strips with a paper cutter, then use scissors to make the insulator. Form it over a track rail.

McMaster-Carr has a variety of forms. Their product 8490K11 is a 12" x 12" sheet of .010 inch thickness for $2.36.

Almost invisible connections can be made to high-rail and Gargraves track by inserting a 1/4 inch, non-insulated, male quick disconnect terminal, from underneath, between rail metal sides. Sometimes it helps to insert a small-bladed screwdriver first to prepare the way. They hold well, but can be also tightened with track pliers.

These come in different wire sizes. For isolated-rails, 22 gauge wire works fine. For power connections, use 18 or 16 gauge. Use a non-insulated terminal crimper to hold the wire in, then solder the wire to the terminal, just to be sure. (Don't solder the terminal to the rail.)

For 22-18 gauge wire, Mouser's part is 517-2247, about $9/100. McMaster Carr's part number is 69525K66, $4/100.

For 16-14 gauge wire, Mouser's part is 517-1650, about $9/100. McMaster Carr's part number is 69525K68, $4/100.

Mouser is on the web at www.mouser.com. Good for all kinds of electrical/electronics stuff. Easy to deal with.

McMaster Carr is on the web at www.mcmaster.com. Great supplier. Good for hardware, wire, tools, etc. The web site is great for finding what you want.

Fistell's is a local electronics source. They have the terminals, and have carried the fish paper, but may have trouble finding it. Great place to browse; lots of junk. 10th and Bannock. Web site is poor, no online ordering: www.fistells.com.