Newbie Needs Help with Electrical Question

Discussion in 'HO Scale Model Trains' started by raj824, Sep 12, 2007.

  1. raj824

    raj824 New Member

    I am new to model railroading as well as to this forum. As you can see, this is my very first post.

    Here is my problem. I am building a wall track that is mounted around in my kids room. I have placed numerous lighted lampost and building lights around the track I've built thus far. I guess there are 13-15 lights thus far that I have running off of one line. To power the lights, I'm using a cheapo tyco transformer (7v max rated) and the wires are connected to the "AC Accessaries" terminal.

    To make it easier for my kids to turn on/off the lights, I brought a toggle switch from home depot. The specs are 10 A 277 V AC / 20 A 125 V AC / 3/4 HP 125-250 V AC. I'm no electrician so I have no idea what all this means.

    Anyways, I ran 16 gauge wire from my toggle switch to the transformer. I then have my wire that connects my lights running to the toggle switch. In other words, the lights are connected to the switch, which is then connected to the transformer.

    Okay, here in is the problem. The switch works perfectly, but when I leave the lights on for an extended period and then turn the switch on/off, I here a click and then nothing. The lights are no longer working. At first I thought I blew out all the lights, but not so. I guess it's a safety feature that's engaging. After I unplug and replug, it's fine again.

    Is it the switch that's causing the problem? Any help would be appreciated.

  2. alexbnfan

    alexbnfan Member

    It may be the overload tripping. The overload happens when you have more amps being drawn than the power pack is rated at.
    Try to get another power pack, I've heard good things about the MRC packs.

    I personally use all sorts of old packs, but i have a big pile of power packs that were not good enough too.

    Is the switch the same you use to turn on lights from the main power supply (ie wall current)? that may be the problem.

    This is all i can think of off the top of my head.
  3. raj824

    raj824 New Member


    Thanks for the quick and courteous response. I'm not sure I follow your second statement. The switch is connected directly to the transformer, which is connected to the wall current. Is that what you mean? If so, then yes.

    Are you saying that I should have one switch to turn on/off the "power" then another switch to turn on and off the lights? Hmmm....I guess that makes sense.
  4. 60103

    60103 Pooh Bah

    Rod: is that power pack rated at 7 Watts? That gives 1/2 amp at 12-14 Volts. You are probably overloading the power pack and it's cutting out. (I don't know what the load per lamp is, but you have to add the amps together.)
    Your switch will handle any load you could come up with on a model railroad.

    You might get a quick and cheap workaround if you find a load of wall transformers from old computers that are rated in the 6 to 12 volt range.
  5. ezdays

    ezdays Out AZ way

    There's no doubt that you are overloading the source. As David says, your power pack is rated at 7 VA, or watts. Again, that's around 1/2 amp at the rated output voltage, barely enough to run a couple of lamps. There is probably a thermal overload switch in the circuit and it cuts out after a short while because of the excessive load. It cools down and restores by the time you've made several attempts to find out what's going on.

    You can buy a 12 volt transformer at Radio Shack that will handle two amps at about 12 volts, or get an even bigger one. I think they even sell a five amp. transformer. Save the power pack to power your trains.
  6. alexbnfan

    alexbnfan Member

    What i mean is it like the sort of switch you use to turn off the lights at the wall, or is it a special electronics switch.

    I hope thats a bit clearer.
  7. ezdays

    ezdays Out AZ way

    There's nothing wrong with using a wall switch to turn your lights on and off. They are usually rated to switch 115 volts and a maximum of 15 amps. Your lamps don't need that heavy duty kind of switch, and might even cause problems down in time because the contacts can get corroded and the lower voltage and current won't keep them clean. I'd opt to use an electronic toggle switch rated at no more than 5 amps.

    One thing you need to find out is the kind of lamps you are using. What voltage are they rated at, and what kind of current do they draw. Once you know that, it's easy to calculate what kind of transformer and switch you'll need. If there are any numbers on your lamps, or if they're in a street lamp or something, let us know what they are.
  8. lester perry

    lester perry Active Member

    I would sugest gettinr an mrc power pack, since it is around thwalls of room you may want to consider a walk aroud type Ihave 2 of them they work very well and have plenty of power. before you spend a lot of money on power supplies you probably shoul look inyo DCC. please forgive spelling errors i am in the hospital due to a stroke
  9. alexbnfan

    alexbnfan Member

    OK, i thought they would generate extra resistance, that may be why its shorting out
  10. eightyeightfan1

    eightyeightfan1 Now I'm AMP'd

    With the old packs the have an "overheat protection" in built in them. To reset alls you have to do is unplug the powerpack, let sit for about fifteen minuates and it should automatically reset.

    One thing you might try is hooking the lights to the DC(Track) side of the transformer. You can control the amount of voltage to the lights. They won't be as bright as with the AC side, but when you add more lights, you just bump up the throttle a little more. But..Get another transformer for running the trains.
  11. Triplex

    Triplex Active Member

    A short is too little resistance, not too much.
  12. alexbnfan

    alexbnfan Member

    You can tell how much i know about electricity!!!!!
  13. diesel

    diesel Member

    Hey raj824,

    As stated above MRC packs are great; the new ones have a feature that keeps your locos from stalling (a little) AND there is an on/off switch built in to most of the packs, not to mention inexpensive sound for a small room.

    alexbnfan, BN is my favorite road, maybe you'll post a pic or 2 of your work.

  14. rhtastro

    rhtastro Member

    Hey Lester, get well soon, we need you on the gauge. RAJ's problem sounds like a classical overload. The simple solution is a larger transformer for the lights. Dan of Diesel above probably is on the right track for power packs. I'm sort of out of this myself since I use an AC system for everything. Trains, switches, lights, etc. everything. bob
  15. nkp174

    nkp174 Active Member

    Commenting on the switch:

    The switch you purchased is telling you an amp/voltage rating. 20A / 125V AC tells you that it designed for up 20amps at 125 volts.
    A Watt (W) is the voltage * the amperage...
    so a 60W lightbulb at 120 V is using 0.5 amps.

    In Europe, the use 220V electric, so a 60W light bulb takes less amperage...but it is still uses 60W. The europeans did that to save money on their copper wiring (more amps, thicker wire)...while we americans/canadians chose to use the safer 120V.

    At 12V, a 60W lightbulb would require 5amps...and something like 14 gauge wire.

    Voltage is the ability for electric to jump...amperage is the amount that is jumping...wattage is how much light, movement, or heat is being generated.

    Since the voltage is 120V between the wall and the transformer...there is no problem with using the switch you have. I recommend following the ideas to purchase a larger power supply from radio shack and maybe an MRC Tech 4 or Control Master 20 (which could handle all of your lights) for the track. I'd place both powerpacks on that same switch you're already using as it is a nice kill switch.

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