027 line is shorting out

First, disconnect the transformer from the track.  If the red light stays on it is the transformer.

Since the track is not screwed down cut loose half the track and see if it is still shorted.  If not connect the transformer to the other half of the track and see if it shorts.  By now you get the picture.  Keep shrinking the track till you find the bad piece.

The last option is your motorized car car is bad.

You have to "Divide and Conquer" the loop in order to find this.

1. As Bill DeBrooke said above, step one is to disconnect the wires from the transformer and see what happens.
2. If the transformer still shows a short with the wires disconnected, the transformer is defective.
3. If the transformer is OK, reconnect the wires to the transformer.
4. Remove all locomotives and cars from the track.
5. Apply power. If there is now no short, the problem is in one of the pieces of equipment that was on the track.
6. Place them back on the track, one at a time, until you find the one that has the short.
7. If you still have a short with nothing on the track, you have to do the "divide and conquer" routine.
8. Take two track joints apart to split the loop in half.
9. Apply power to each half of the loop, one at a time.
10. One section will show the short, one section won't.
11. Take two track joints apart to split the loop again.
12. Apply power to each half of the loop, one section at a time.
13. One section will show the short, one section won't.
14. Carefully inspect the section that shows the short and locate the defect.
15. DONE!

Thank you both for your helpful responses.  I have a bus line, shoot power to both sides of the layout.  I disconnected to take it out of the picture.  I separated the layout into about six sections, taking the track apart.  I went around with a small transformer and a clip on and connected each section independently.  Each section tested fine.  I first turned up the transformer.  The red light did not come on.  I than placed a caboose with a light.  It was fine for each section.  Now I’m thinking that somehow the bus line is bad or hooked up wrong.  Before I did anything else I reconnected the six sections back to one.  Instead of hooking the track back to the bus line, I connected the small transformer, using the clip on, to the track.  What the ****...... the red light comes back on.  So divided we are fine, together it fails.  Any thoughts?  

Thank you again.      Fred O.

Only thing I can come up with is there is a track connection issue somewhere where one of the groups of tracks connects to the next group. I would try connecting the groups  one end at a time, testing the power each time, until you've completed the loop or pop the breaker again.

That should solve it.  Thanks again.  Will let you know how I make out.

Fred O.

Have not been able to solve.  No sooner the problem seems to have gone away, it reappears.   When I disconnect track the red light goes out.  Then I  start adding track one by one by one and the red light does not come o.  Once the track is all back together it continues not to short out.  I run a train for 5 minutes.  Everything is fine.  I move onto to something else and come back later and the problem is back.  I‘ve done this three times with the same result.  It’s not the transformers,  since the problem has happened with both.  I have a ZW transformer for which a separate line is running fine.  

Let me know if any of this new info provide a clue.  

Thank you again.

Fred

Is the control that keeps popping the breaker on the ZW too?   Can you temporarily wire the problem loop to the ZW  controls running a train without a problem? And the train that's running fine to the transformer that keeps popping the breaker?  

I'm curious as to the result, but I'm stumped.

Just a side bar, the breaker on the ZW is designed to protect the transformer, not your train. I understand if you're running other than standard postwar stuff, you want to put an inline 10A fuse on the positive feed to the track, the electronics in the newer trains (Lion Chief, TMCC, Legacy, etc..)  could be toasted before the ZW breaker pops.  I have two post war ZW's and any feeds for track power for my Lion Chief engines have a 10A fuse and fuse holder (from Advance Auto Parts). Cheap insurance.

Since you said you had to replace the insulation on a piece, I'm assuming you're working with 0-gauge tubular track. I'd go through the list Rich posted above again starting with #4

I ran into a 36 inch section of 027 track years ago that would only short out if it was deflected slightly. So the weight of the engine would make it short out. I had never seen that either before or since. Also, you mentioned a lighted caboose, I have seen those short out intermittently sometimes. My suggestion would be to just take the caboose off and set it aside and run the train for a while without it and see what happens.

Is the wire you are using individual wires or is it like a lamp wire, together?  I would try different wire.  That is about the only thing you have not tried.

if you have an ohm meter, one track section at a time connect one lead of meter to outside rail and other to middle rail. Meter should read zero. Apply pressure to middle rail, try to wiggle it a little and see if the meter jumps up with a reading. If it does that is your bad section. You haven't stated what engine you are running. When the short appears it goes away when you disconnect the transformer but does it stay on when you take the equipment off the track but haven't disconnected the transformer?

@Tman129 posted:

I understand if you're running other than standard postwar stuff, you want to put an inline 10A fuse on the positive feed to the track, the electronics in the newer trains (Lion Chief, TMCC, Legacy, etc..)  could be toasted before the ZW breaker pops....  ... Cheap insurance.

No insurance, actually. The breaker on the ZW is designed to protect the transformer, not your train. You need transient voltage suppression, which actually is cheap insurance, to clamp high voltage spikes, something no fuse or breaker can provide.

On my prewar layout I use prewar Lionel standard and O gauge track. Before I selected a section I used an ohm-meter as @Forest mentioned. Each section was twisted side to side to ensure the insulated paper was solid and not shorting out. I did find a few with cracked or worn pieces which were easily corrected. Haven’t had any issues for the last year with them.

Hope you resolve it sooner than later so you can get your trains on the rails for your grandkids.

A long shot, but are the wires on your lockon intermittently touching?

Belated thanks for your help and as well as everyone else who responded.  Woke up yesterday morning with a thought that there was one thing I had not checked out.  I had inspected the insulation pieces for the center hot rail only from the top and every thing looked centered and good.   When I turned them over I found two that looked suspect, so I replaced them and was in business.  Thank you again!!!     Merry Christmas to all and to all a good night....... best to you and your families.  

Fred

Yea!