Hello I recently received a box of Marx, Lionel and A.F. signals and devices. One of these is a Marx circuit breaker. There is one wire going to an insulated post. one ground terminal, and a third wire hanging down unattached. Were these effective as a circuit breaker? I know very little about Marx and was looking for information about this




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It's from a time when many transformers didn't have integrated circuit protection. While it may still work I would keep it on the shelf as a conversation piece and not rely on it for regular operation. In operation it is wired in between the track and transformer.

Jim McC

   They worked. But I don't recall how exactly.  I think there should only be a hot in and a hot out for this #420 and Lit if on. The third leg would likely go to common. Especially if modified to light on point break. Can you get inside and describe what's seen or take a picture to tell for sure ? It wont be hard to figure out. (Assuming nobody else has a fast answer)

"Still trying to not shoot my eye out"


"Nursing insomnia one railcar at a time"

My aroma therapy? Smoke Pellets.


It is a thermal breaker.  It can be checked for operation with a direct short and a count to ten. No more or less effective than any other thermal breaker from Lionel or in the power seats of the car you drive today. If it is in good shape and wasn't overheated to the point of abuse it will do the job it was made for.

There are better options today sure. Mostly IN modern transformers, but this is not useless and too dangerous to consider using just because it's old. 

"Still trying to not shoot my eye out"


"Nursing insomnia one railcar at a time"

My aroma therapy? Smoke Pellets.


Nor would it be great for very large postwar. But for up to two small Marx?  If used with a non breakered transformer, it would be better than none also.

I still use a prewar Jefferson, (fused externally; same thing) And a Lionel Z. Marx 1669, 1239, & 1209 with thermals. I check things out on the inside first .

"Still trying to not shoot my eye out"


"Nursing insomnia one railcar at a time"

My aroma therapy? Smoke Pellets.


Mark Wags posted:

Thank you for all of the information.  I know so little of Marx and was curious as to how this operated.

The third wire is probably for the indicator light.  Basically, the breaker works thermally, with the light wired in parallel.  When there is a short circuit, the thermal breaker heats up and opens.   At that point,  power goes to the light instead, and it lights up.  

I wrote an article on Lionel and Marx breakers for the CTT forum back in 2014, but what with Photobucket getting hinky, it no longer has pictures.   I'll see about reposting it here. 


It's crackers to give a rozzer the dropsy in snide!


Remember, SCROUNGE!

My grandfather wired one of these in between track and transformer on the plywood sheet layout he gave me in the 1940's.  Immediately after l got it, l derailed the train and got a short.  Train wouldn't run. Later in the day he came by and said, "Push the button!".  Worked great with one of those vertical Marx transformers with the easy to move rheostat lever.  How come, on the later horizontal Marx transformers, you almost need a locking pliars to move the lever?

??Another one of THOSE!!??  What you want to sell is not what I want to buy!

The wire going to the insulated post went directly to the lamp. I attached the free wire to the same post as the lamp wire and got the unit working. it really responds very fast to a short. Whats neat about it is a blinking red message "Short Circuit" appears in the window at the top until reset.

Mark Wags posted:

Also in this set were these 2 items. Are these prewar items also?20180729_010413

Hi Mark, those are both prewar, they are (judging by the picture) both the same model of circuit breaker made by Marx, just in different colors.



The last two accessories are 407 Automatic Crossing Signals.  Marx used the square base for a number of accessories and the top used on the circuit breaker is also used on the 407 Automatic Crossing Signal and the 605 Illuminated Bumper.  Just different lettering on the face.  Since the tops are interchangeable they are often incorrectly put on the wrong base.



I had one of those Marx circuit breakers on my childhood O27 Marx 999 engine layout that worked great.  I opened the CB and saw how it works.

Below is a photo of my control panel Marx copied circuit breaker shown on top.  The "Reset" red circuit breaker button on a $3, 6 amp circuit breaker wired in series to one of my Lionel LW transformers.  The red lens over the "Short" hides an 18 v light bulb that us wired across the two contacts of the CB.  When a short occurs, and the CB opens, power is cut to the trains and all the power to the track goes to the bulb and indicates in red a short has occurred.

This works great for my conventional control, post war O27 layout which runs mostly Marx and Lionel trains.  I have no modern trains with newer less rugged electronics that may require faster working protection.


Train Lots 5-10-2016 251

I have three such circuit breaker for my 3 Lionel LW transformers and been using them for over 40 years.  I uses these 6 amp circuit breakers for two lighting circuits and a switch operating transformer.  I do not need to put a light across the CB contacts as I can tell when they throw (lights go out and switches do not operate).


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