Lighting for 3/4" Scale Steam Locomotives

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PRR G5s
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Lighting for 3/4" Scale Steam Locomotives

Post by PRR G5s »

I'm working on detailing my 3/4" scale PRR K4s, and was wondering what others do for wiring the headlight. I was planning on grounding the bulb to the headlight frame/loco frame, and then run the "hot" wire through the handrail. Unfortunately, when I did this on my 3/4" scale PRR G5s, the heat melted the wire insulation, and therefore shorted the system out.

I am using brass tubing for the handrail, with an 3/32" O.D. and 1/16" I.D. Is there a wire out there with high temperature insulation that will fit inside this tube, or am I stuck with day time running only? I thought about wrapping a wire in masking tape, but I think that will burn off as well. I've tried looking on the Internet, but have yet to find something. Thanks in advance for the help.

Eric L.
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Will's 2882
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Re: Lighting for 3/4" Scale Steam Locomotives

Post by Will's 2882 »

There is Aircraft wire that is high temp, PM me and I'll send you what you need.
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dnevil
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Re: Lighting for 3/4" Scale Steam Locomotives

Post by dnevil »

You can also look at Teflon coated wire (which may be the same thing as Aircraft wire?). It is good up to 500 degrees F.

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NP317
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Re: Lighting for 3/4" Scale Steam Locomotives

Post by NP317 »

I believe the designation for Teflon coated wire is "THHN."
When I was restoring full-sized steamer locomotives, I would purchase aircraft THHN wiring from Boeing Surplus.
As far as I know it is still working properly, decades later.
I do not know if it is available in the small diameters we need for our models.
~RN
Last edited by NP317 on Wed Mar 29, 2017 9:41 am, edited 1 time in total.
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Harold_V
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Re: Lighting for 3/4" Scale Steam Locomotives

Post by Harold_V »

THHN is not Teflon, although it does tolerate lower heat. Teflon wire is a single layer coating, while THHN has two layers, the outside layer being transparent. THHN is good up to 194° F, while Teflon should withstand up to 500° F.

Harold
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GregE
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Re: Lighting for 3/4" Scale Steam Locomotives

Post by GregE »

Silicone coated wire is rated for 200C or 394F.
I see it's available on amazon down to 28 or 30 gauge. There isn't an OD specified, but that might have a chance of fitting your tubing.
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Re: Lighting for 3/4" Scale Steam Locomotives

Post by ccvstmr »

Eric...THHN is a wire insulation designation. It comes with a clear plastic coating over the colored insulation. The plastic coating is intended to reduce friction while pulling wire(s) thru conduits. Don't think this will be an issue in your case as you're only feeding 1 wire thru your handrail tubing. The fact that the wire is run thru a piece of tubing...might be considered "air cooled". Still, the handrail stanchions will create points where heat can soak thru.

Teflon and silicone insulated wires have higher rated temps as indicated. Ebay or "good" hobby stores might have such insulated wire for use in R/C models. Suspect you won't need much wire. I would stay away from a single, solid wire and opt for stranded wire. If you nick a single solid conductor, it's liable to break at that point. Stranded wire is a little more forgiving when it comes to wire bends.

Don't know what you're using for a light bulb. LED's are available in a variety of colors...including bright white and warm white. Warm white might look a little better from a nostalgia perspective. Bright white will provide more illumination during night running.

Hope that helps. Carl B.
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NP317
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Re: Lighting for 3/4" Scale Steam Locomotives

Post by NP317 »

Harold_V wrote:THHN is not Teflon, although it does tolerate lower heat. Teflon wire is a single layer coating, while THHN has two layers, the outside layer being transparent. THHN is good up to 194° F, while Teflon should withstand up to 500° F.

Harold
Thanks for that correction, and good information.
~RN
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