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Subject: Double Deck Layout Lighting with C9 Bulbs

Date: Friday, September 03, 2004


Bram Bailey, Ontario Central Railway, Vermilion, OH


Double decked layouts complicate lighting because the upper deck shades the lower level from conventional illumination.  Because of this issue, lighting channels for the lower level were designed into the benchwork for the upper level.  The bottom of the upper level is covered with 1/8" Masonite painted white.  This serves two purposes.  The obvious one is that it traps dust and foreign matter from dropping onto the lower level. Its white color serves as a reflector to bounce light back to the surface. Open benchwork would not do this very efficiently and would also tint the light the same color as the wood. The upper level lighting channel is part of the valence. 


When I lived Syracuse I experimented with C9 type 7 Watt outdoor Christmas lights for layout illumination.  Though the layout never neared completion, the lighting was a success.  I even did a clinic on it at a Niagara Frontier Regional NMRA convention.  The advantage of this type of lighting is that the many low wattage bulbs give a soft even lighting effect.  By using various colors combined with 2000 Watt dimmers, sunrise, sunset, night as well as daylight can be simulated.  This is high voltage AC work and if you do not understand your local codes this work would be best left to a licensed electrician.


The main building block of this lighting system is the basic outdoor Christmas light set consisting of 25 seven watt lights spaced on 12" centers.  When I deploy this system, four strings are used for a given area and they are staggered so that a light socket appears every 3".


Two strings are dedicated to clear bulbs. These are used to simulate daylight. One string is populated with blue bulbs to simulate night.  The last string consists of alternating red and orange bulbs to represent sunrise and sunset. 


When installed the configuration is as follows:

      Position 1, Circuit 1 = Clear

      Position 2, Circuit 2 = Blue

      Position 3, Circuit 3 = Clear

      Position 4, Circuit 4 = Red

      Position 5, Circuit 1 = Clear

      Position 6, Circuit 2 = Blue

      Position 7, Circuit 3 = Clear

      Position 8, Circuit 4 = Orange

After position #8, the configuration repeats itself.  


The 2000 watt dimmers have the capacity to drive 285 lamps per circuit limiting the system to 285 linear feet of layout.  Since the OCR requires 335 feet of lighting, I had to add another white circuit and thin out the orange/red circuit by eliminating every seventh light.  The blue lights are not driven by a dimmer, so the 20 amp circuit is the limiting factor.  The 335 blue lights draw 19.5 amps coming in just under the wire.  I thinned out about 10% of the blue lights primarily in the rural areas to de-load the circuit.


Care must be taken not to overload the system. Typically, the lights are rated for a maximum of two strings fed from a single source.  The built in fuses in the plugs will clear if loaded beyond this rating to protect the wires from a potential overload.  When I engineered the system, no more than 50 bulbs are fed from a single socket and the original plugs are retained with the internal fusing to protect against overload.  The sockets and plugs are color coded so that it is easy to trouble shoot the system later.


The manufacturers of the Christmas lights caution against using metal stapes to secure them  I sewed the cables in place telephone style with nylon "12 cord" and used plastic cable ties that have a hole for a screw to keep the sockets in alignment.  The inside of the valence is covered with Nashua #322 Aluminum Foil tape.  This is intended for sealing joints in foil jacketed insulation and is available at most home improvement centers.  The foil tape serves as a reflector increasing the efficiency of the system by about 40%.


Before the benchwork was complete, 12 gauge Romex power feeders for the lighting system were run around the basement.  At each of the feeder locations, a series of sockets were installed above the drop ceiling and color coded.  For double deck sections the upper plug would serve the upper level and the lower plug would feed the lower level for each circuit.  If it is necessary to isolate the system for maintenance, it is simply a matter of pulling the plugs.


When the system is in operation for daylight hours, the white light circuits are on and the others are off.  When I want to make the transition to night, I first turn on the blue lights.  This is done with a switch because when they come on in daylight, it is not noticeable over the ambient light therefore you can save the cost of a dimmer.  To represent the sunset, I crank up the orange/red string and then bring down the white lights slowly.  You can control how spectacular the sunset is by how long you leave on the orange/red string.  Once you reduce the intensity of the orange/red lamps, you are left with only the blue to represent night.  When it is time for sunrise, just reverse the sequence.


The finished layout lighting system consists of 1280 bulbs.  That's almost 52 strings of Christmas lights!  Needless to say, I did a lot of shopping at the after Christmas sales!  The good news is that this system provides wonderful effects for both the operator and visitor.  One would assume that this many incandescent bulbs would generate a significant amount of heat.  Since these bulbs were designed to be used in the rain or snow, they run cool enough to touch and therefore do not generate an inordinate amount of heat.  The bad news is that this system is a power hog drawing about 4.7KW during normal operation (with all bulbs illuminated, the system draws almost 9KW).  Because of this, I use it only during operating sessions.  For maintenance, I use the florescent aisle lighting and some portable clamp on incandescent lights if I need to get intense illumination into a specific area.


One major word of caution here.  We are dealing with high voltage wiring.  Poor engineering and overloading can result in a fire.  If you do not have a working knowledge of AC power circuits, have an electrician help you.


Another suggestion is when you are splicing the Christmas lights, use heat shrink tubing.  Most shrink tubing is rated for 600V, but I use a double layer of shrink tubing on all of these splices, just to keep Mr. Murphy at bay.  The advantage of heat shrink tubing is that it will not unravel over time like electrician's tape will.



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