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On another thread ( I sorta opened a can of worms, and diverted the discussion from the original topic, by bringing up series wiring.  I don't want to continue to divert the topic there so I'm starting a new thread.

I mentioned that years ago for the1st time using Lionel street lamps that I wired them in series and what I observed was a continual dimming from the first light on down.  That was challenged in the other thread as not possible.  I know what I saw so Yesterday I got a brand new 3-pack of Lionel street lights (I mention new because it was suggested that my observation could only happen in the lights were not identical) and ran 2 tests using different wiring patterns.

For ease of explanation say each lights wires are numbered wire 1 and wire 2.

Test 1: I connected all 'wire 1' wires together and tied them to POS on the trannie.  Connected all "wire 2" wires and connected that to Ground on the trannie, sort of simulated parallel wiring, sorta.  Here's the result:


TEST 2: connect POS on the trannie to wire 1 on first light.  Connect first light's wire 2 to 2nd light's wire 1, and continue for 3rd light.  sorta like "daisy chaining'.  Here's the result.  BTW: the trannie setting was the same in both tests.  Light 1 and 2 were very dimly lit and light 3 didn't even light.


I might be directing this to the person that questioned my statement, a person that I highly, highly respect his electrical knowledge and told him so.  I'm not looking to pick a fight with him (john) but hope that he sees this and helps me understand.

I would LOVE to simplify my Christmas layout light wiring using series wiring so if I'm doing something wrong, please tell me what it is, OK?

- walt


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Last edited by walt rapp
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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!

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.

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.

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

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