series versus parallel wiring for lights

It could possibly be voltage drop due to the tiny wires with lighting being done in series, in my opinion only. I know it would be more wiring and work but I would recommend running buss wires for both hot and common wires (like it's done in house wiring) and tap off each so all your lighting is parallel wired, then all your lighting should be the same brightness no matter how many lights you put on them. In series each light you add takes a share of the voltage amount supplied, and some of the lights may for one reason or another may be dimmer or not light. Good luck Walt!

Swap light #3 (the dark one) with light #2 using the same series wiring scheme.

I'll bet light #3 is still dark in the middle position (and light #2 stays dim in the last position).  If not, this would be nothing less than fascinating!

Stan is right, on the other thread I offered the opinion that the lights are NOT the same.  Specifically, the bulbs clearly have different resistance or I can't imagine how this could happen.  As Stan says, if it doesn't work that way, it would be, at the very least, verrrrrrrry interesting!

Resistances in series are known as a voltage divider. With light 1 and light 2 you have added two resistances together resulting in more voltage drop (R1 + R2 = Rtotal).  Add in light three (Resistance 3) and there is not enough voltage to light the element, but current can pass to complete the circuit and keep lights 1 and 2 illuminated, but dimmer (less voltage).  Put them in // and the voltage across each resistance remains the same.  The series equation is as follows:  V1 = (R1/(R1+R2))*V where V1 is the voltage across light 1, V is the source voltage.  V2 is similar in that V2 = (R2/(R1+R2))*V.

Walt, although I used different lights (Town and Country), I wired them as Gary P suggested, and also lowered the voltage a bit, so the bulbs last longer. I used 16 gauge wire as the buss.

I would prefer to wire in parallel and use berg or molex connectors to hook up to the lights if this is going to be a yearly setup.   If the light bulbs are incandescent then polarity of the wires won't matter.  If they are led lights then use a red sharpie or paint pen and color one wire to indicate the polarity.

With series wiring each bulb will drop (or consume) a certain voltage.  The amount of voltage consumed by each bulb will determine their individual brightness.  The three lights will divide the total voltage according to the drain/load of each light.  Given the quality of today's toy products, the variance in the internal wire, the bulb, or internal series resistors would all have an influence from light to light.  The size of wire that you use to connect them to your power source could have an influence also.

With parallel wiring,  each light will get roughly the same voltage.  The voltage would decrease down the wiring according to the size of your parallel wires used.   26 or 28 gauge would possibly be noticeable while 12 gauge wire would not be noticeable.

You could lay three passenger cars on their side and connect them with clip leads in series going from pickup rollers of one car to the axle of the next car to see if you have any variation in brightness.  If you put them on the track and connect your power source to the rails then they would be in parallel.  It should take more voltage to light the cars in series than in parallel.

Walt,

If you have an ohmmeter, check the resistance of each lamp.

I love all of the comments made here.

A point of clarification: I DO use parallel / bus wiring on my Christmas layouts - ever since the learning experience in year 1.

Another point: As I mentioned, I used a BRAND NEW UNOPENED 3-pack of Lionel lights trying to make sure that they were identical.  I'm not electrically smart enough to know if one could have been different.  I already put the lights away and they are now mixed in with my other 20 Lionel Lights so I have no way to repeat the test swapping light 2 with light 3.  I would have liked to try that.

John H: I would have liked to do that test but as I said I now have no idea what lights that I used

John, I hope that you are OK with me starting this thread.  I appreciate all of your contributions and I've learned a ton of things from you.  But my own curiosity got the best of me and I just had to try this to satisfy my own ego.

To me Farmer-Joe said what I was thinking  Thanks for stating it in correct electrical terminology.

One of the great things about this forum is to intelligently and politely discuss topics when opinions can vary.

- walt

@walt rapp posted:

John, I hope that you are OK with me starting this thread.  I appreciate all of your contributions and I've learned a ton of things from you.  But my own curiosity got the best of me and I just had to try this to satisfy my own ego.

I have no problem with rational discussions.