I purchased some time ago a package of miniature incandescent lamps for adding lighting to my layout structures. The specifications of the lamps are: 14v 80mA 5.5mm Dia. My problem is I want to wire several of these in series but both wires on the lamps are black. I looked at the wires under a lighted magnifyer to see if one was marked different. No luck.
Is there any way I can tell which wire is the common one - or the hot one? If the wires from one lamp gets switched during hookup I assume a short will occur. If a short occurs will the bulb(s) be damaged? I also have a package of small bulbs that have a screw base with two wires that are color coded. To me, that means its’ important.
first, just an opinion, the bulbs won’t short just because the wires are reversed unless they’re mounted on a panel that will conduct power (through the bases for example). Usually they are not marked if it won’t matter ( no base used). Wiring in parallel would keep each bulb lit if one goes out, but would make bulbs burn brighter.
The bulbs I’m speaking of have no shell. They are all glass and the two wires come out of that glass. I just can’t tell from looking how to hook several up and get the same connections (common to common, etc). I wanted to avoid connecting each light to a separate hookup on a terminal strip. Connecting in series is probably not the best way, but I’m not sure how to do it in parallel and still avoid using up valuable terminal strip real estate. I assume if the bulbs are connected individually it won’t matter which wire is common and hot. Another thought I had was to run a common and hot from the terminal strip to the general area of the lamps and tie in the lamps at convenient points. Think that would work?
You can run a wire loop from a switch, or transformer terminal for the hot and ground wires, and connect one side of the light to the hot wire loop, and ground to the ground loop with tap splices.
I’m connecting LED’s like this, and can’t tell which side is which. Here’s a parallel diagram.
Is that diagram showing how you are wiring your leds a parallel scheme? If so, I guess I have forgotten the difference between series and parallel wiring. If I understand correctly, your diagram indicates the lights are connected together and the power enters the group from the one light. That is exactly what I want to do. I have already done that with four PW lamp posts.
With parallel wiring you can keep the voltage lower as well, just need a more powerful transformer-watt or amp wize. Each lamp will draw the power it needs.
With series wiring, as others have mentioned, when one light goes out they all go out and the voltage and brightness can vary unless your light bulbs are the same wattage.
I have the old GE Mazda lights(about 8 to 10) in parallel circuit on a 13 volt AC source, they burn bright enough but not too bright like they would if I put them on 17.5 volts AC like they would in an old Christmas light set. You can use a lower voltage setting and get a little longer life out of your light bulbs.
With an incandescent lamp, the wires are interchangeable, which is why they didn’t bother to mark them.
In power wiring, the shell of the socket should always be connected to the grounded conductor, not because the incandescent lamp cares which way it is wired, but so that anyone accidentally touching the shell while screwing a lamp in or out will not touch a dangerous voltage. In many countries, they use bayonet lamp bases with two contacts, so that the shell of the base is not involved in the power circuit.
BillBobBoy1, if you are not too far along in your layout progress, here’s a different idea. I use the small mini-CHRISTmas lights for illuminating all sorts of things. Most of the commonly sold light chains use a 2.5-3.5v bulb. But there are shorter chains that utilize either 6v or 12v bulbs. I just cut the light chains apart so I have the bulb base and enough wire lead.
I can think of no cheap or cost effective way to illuminate a layout than using these mini-CHRISTmas lights. Since I run my layout on DC current without any digital command, I find lower voltage bulbs suit my needs better. So I often replace lights in train cars and locos with 6-7v mini-CHRISTmas llights… they work great! Can’t beat the price either, especially if you buy the chains during the post-holiday sales.
One advantage of using smaller transformers to power accessories/lights is that you can “customize” the voltage more accurately. For example, the basic no-frills K-Line starter set transformer is both common and cheap. It’s not a high amperage transformer, but it does start at a zero voltage and goes upward very gradually. This transformer will power those 2.5-3.5v bulbs very nicely. And because of the lower power requirement of the bulb, you can power more lights off this transformer versus powering 12v bulbs off the same one.
Also available around the holiday season are these nifty self-adhesive plastic clips to hold the mini-light fixture base in place. I use these in train cars too… they work great, so I can get the lights inside the train car where I want them to be.
I do use the bulbs you described BillBob, but for specialized purposes like doorway lights, or on one of my factory buildings I built an exteneded loading dock with a roof. I used those small bulbs with attached wires for lighting the dock, with small holes drilled into the building to allow the lights to be placed beneath the roof over the loading platform.
I heavily revised an MTH Operating Loading Platform,
