Easy Lighting for Outdoor Railroads
Easy Lighting for Outdoor Railroads
|
HOME |
It is dusk, the street lights are on and the windows of all the buildings glow as the people who live there go about their evening business. Here is the easy, low-cost way to make it happen on your layout. This article assumes you know little or nothing about electricity. If you already have your Ph.D. in electrical engineering, you may sit quietly while the rest of us read through it.
Low voltage is a must. All outdoor model railroad lighting should be low voltage for safety. There may be times to risk your life, but this is not one of them. Low voltage means either battery power, or normal house power stepped down to a safe voltage by means of a transformer. Twelve volts seems to be the most common voltage used, possibly because it is high enough to allow reasonably sized wires to carry enough power to be useful but still low enough to avoid electrical shock. But other voltages, up to 24 volts, are useable. Above 24 volts the wiring becomes subject to inspection (at least in Canada) which takes it out of the class of easy lighting. Outdoor transformers. Selecting 12 volts for lighting has an added bonus. There is on the market a variety of totally enclosed, weatherproof transformers complete with timers and photocells for automatic operation. These are sold for operating low voltage garden lighting and are perfect for low voltage garden railroad lighting as well. You can even combine the two, as long as you are careful to avoid exceeding the transformer's rating. More on ratings later. Indoor transformers require fuses. If you prefer, you can run your lights from an old Lionel or Marx 0-27 gauge transformer. However, these are NOT weatherproof and are suitable for indoor operation only. Indoor operation of the transformer that is. Wiring can be safely run from a transformer kept indoors to lights which are outdoors. But for safety sake, an inline fuse equal to the transformers current rating is a must. It should be connected in series with the transformer output right at the transformer.
You can calculate the current rating for the transformer and for the fuse by dividing the power rating of the transformer by the voltage. The power rating may be in Watts or in Volt Amperes. For example, my old Lionel transformer in the photo is rated at 45 watts, 8 to 15 Volts. A suitable fuse would be 45/15 = 3 Amps. By choosing the maximum output voltage I got a conservative fuse rating. You could set this transformer at 11.25 volts and use a 4 Amp fuse, but if someday you accidentally turned it up to full voltage, it would be over fused by 33%. I prefer not to take that chance. Speaking of chances, your transformer may have a circuit breaker or an "overload reset" button. Would I take a chance on an old circuit breaker in place of a fuse? Would I risk my $100,000 house for the sake of a $1 fuse? Not a chance! Choosing lights. Twelve volt circuits mean twelve volts lights, right? Well, that is a definite maybe. Twelve volt automotive dash lamps are a possibility, especially when you want a few bright lights, and you can accept a limited life. Type #194 (wedge base) is rated 3 watts, 2500 hours life. If you want to use sockets, #52 (miniature screw base) and #53 (miniature bayonet base) are 3/8" round bulbs rated 1.5 watts, 1000 hours and #1487 (miniature screw base) and #1815 (miniature bayonet base) are 3/8" tubular bulbs rated 2.5 watts, 3000 hours. These lamps are all available at Radio Shack for about a dollar each (that's a Canadian Loonie, folks.) Screw and bayonet sockets for these lights run about 50 cents each. Alternately, Christmas lights can be used. Twelve volt Christmas lights are no longer manufactured but 6 volt and 3.5 volt ones are. These can be strung in series across 12 volts in various ways to achieve various effects. For example if you connect two identical 6 volt lights in series across 12 volts, each lamp will receive 6 volts, its full rated voltage. At this voltage, it will glow brightly and last about 1000 hours. But if you connect three in series to make a sort of mini string, and connect that string across 12 volts, each bulb will receive only 4 volts, and some marvelous things will happen. Firstly, the glow will be softer and more yellow, which tends to look better, particularly in older style buildings. Secondly, we will have extra lights that we can position at different points inside the building for more even lighting without drawing any more current from our transformer. And thirdly, the lights will last a very long time, about 22 years if you leave them on night and day. Not bad for lights that cost as little as a dime apiece, including sockets (strings of 20 sell for about $2 at Christmas - lay in a stock when they are available.) The 3.5 volt Christmas bulbs are similar except that they are sold in strings of 35 lights or sometimes 100 lights. They can be connected in strings of 4 or 5 across 12 volts for more light or softer light/longer life. Because a string of four 6 volt lights draws only about 1.5 watts and a string of five 3.5 volt lights draws only about 2 watts, many strings may be connected in parallel across your transformer. Series connections in parallel??!!! Yes. You probably do it every Christmas without thinking about it if you put several strings of mini lights on your tree. Each string of lights is wired in series. That is, the electricity must go through each bulb in turn to get from one end of the string to the other. There is just one path for the electricity. That is why they all go out if you pull out just one bulb. But when you plug all the strings into the wall, the strings are connected in parallel. That is, each string is an alternate path for the electricity to flow and interrupting one path does not affect the other paths. How this can be done in outdoor railroad buildings can be explained with a diagram.
Outdoor connections. In the photo above, the ends of the wires between the light sockets have been stripped bare of insulation for about 1/2 inch, and the bare copper strands twisted together. This is ok for testing the lighting to be sure it works, but it will not last for long. To make a lasting joint, the wires need to be soldered and wrapped with electrical tape. For best results, terminal lugs should also be soldered after they are crimped on, especially if you are going to bury them. Another trick that will help if you bury your terminal blocks is to sparingly coat both sides of the lugs and nuts with silicone grease (sold at automotive stores for greasing spark plugs.) Ratings, rantings, and ravings. It is important to not exceed the power rating of your lighting transformer. They don't like it and you won't like it either if you have to replace a burned out one. My lighting transformer, bought with a set of lights, is rated at 50 watts, which seems to be pretty typical. That means all the lights that I connect to it cannot exceed a total of 50 watts. It was purchased as part of a set that included 12 "moon lights" rated at 4 watts each. Not much extra for running building lights. But nobody said I had to connect all those moon lights. So I used 6 of them which totaled 24 watts, leaving 26 watts for buildings. Now as it happens, I really like the mini strings of Christmas lights and at the moment have 10 of them installed. That is about 20 watts. So I have only 6 watts left. But this summer I want to add four street lights using pairs of 6 volt Christmas tree lights, and put lights in another building. That will be 10 more watts. Well, I could uninstall one moon light and just make it, or I could replace the original 4 watt #918 bulbs in the moon lights with 3 watt # 194 bulbs and make it with a couple of watts to spare. Better yet, I could buy another lighting transformer and be done with it. Epilogue. Ever wonder why they quit making 12 volt Christmas lights? Or are you even old enough to remember those cone shaped lights with the little red beads on the sockets for holding them onto the branches? Originally, they were sold 10 in a string, and the bulbs would last perhaps 1000 hours before you had to work your way along the string, unscrewing bulbs and screwing in spares until you found the one that had burned out. The math worked. 120 volts divided by 10 bulbs was 12 volts. Well and good. But then the manufacturers started putting eight in a string. Made them more profit, I suppose. But the math wasn't quite so good. 120 volts divided by 8 bulbs was 15 volts per bulb and the life dropped to about 55 hours. Then they got really greedy and went to 7 in a string, a little over 17 volts per bulb, and a life of about 10 hours. By now you were spending more time looking for dead bulbs than sitting admiring your tree. Everybody quit buying that type of light. I wonder why. For the technically minded who are wondering about those estimates of
bulb life, Spectrol advised some years ago that the life for small lamps
varied inversely as the 13th power of the voltage ratio. This means that
if we operate a bulb at 2/3 of its rated voltage, it will last
Postscript. Sometimes nice things unexpectedly happen. Shortly after finishing this article, I dropped into a garage sale, looking for some old telephones for my HO layout, and what did I find but a complete set of garden lights, including transformer, for all of two dollars (that's a Canadian Toonie, folks.) Most of the lights were shot, the bulbs dead and the plastic disintegrated from too long in the sun, but lo and behold, the transformer works! Now where did I put those Christmas lights... Jim
|
The 3 Amp fuse
connected to the transformer at left is a blade type automotive fuse. Tubular
fuses are fine as well. The fuse is in series with one of the red wires
going to the lights. Series means all the electricity must flow through
the fuse on its way to the lights; there is no alternate path. Note that
the cord that carries house power to the transformer is not seen in this
photo. With the speed control set just past half way, this Lionel transformer
produces 12 volts.
At
the top of the photo is a terminal block with two terminals. It is convenient
to have one in each building or each group of buildings. This particular
block was made using 1/4 inch stainless steel bolts with 3 stainless steel
nuts on each bolt. The first nuts hold the bolts in the insulating block.
The second nuts hold the two wires from the transformer, one on each bolt.
Actually, the wires may not come directly from the transformer, they may
come from another block just like this one but located closer to the transformer.
The second nuts may also hold two other wires, one on each bolt, that go
to another block just like this one but located farther away from the transformer.
The top nuts hold the two wires coming from the lights in the building,
one to each bolt. The left hand wire is already connected to the left hand
bolt but the right hand wire has been left off to show the crimp-on terminal
lug which is used to keep all the strands in the wire together and under
control. These lugs are not absolutely necessary, but do make a neater,
more reliable job of it. The two wires for the lights in a nearby building
could also be held under the top nuts, to save on terminal strips. The
terminal strips can be hidden inside buildings or in a pinch, buried in
plastic bags. Note - the bulbs in the photo just happen to be coloured
ones. Before using them, the coloured lacquer can be removed by scraping
it with a knife or by washing it off with lacquer thinner.