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I'm running 3 ovals (largest 5'X7') on Fastrack.  I'm using 2 Z1000's and a Z500 through a MTH TIU.  I've had 2 boards on both Proto 2 & 3 locos fry out.  How, where, and what circuit breakers/fuse should also be installed to hopefully prevent a third strike?  Electricity and I are far from being friends.

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Sorry Rob, but what little research I did I still do not understand what passive mode is.  I will try to find the book tomorrow.  Z1000 wired to TIU, then out to track.  I'm using the handheld remote for Proto 2.0 & 3.0 (strictly 3.0 this year).  I guess this is not as easy as it appears to run a simple loop.  The tracks may have come unseparated or the train got derailed (bad Cat) prior to the arc and bark issues. 


That's not the passive mode. The TIU has TVS diodes, but to prevent further issues from transient voltage spikes, you should install TVS diodes in each of your power districts, or even better, on board each power unit you are protecting.  Breakers or fuses won't provide this protection as they are current limiting devices designed to protect the transformers and wiring. The TIU has its own fuses.

Thank you Rob, but I guess my level of electrical knowledge is probably well below any Amish folk.  I've never heard of TVS diodes and have yet to find the MTH TIU manual.   My power district is a 5' X 7' oval around a tree.  I would like to have three separate ovals operated through 1 TIU to run DCS on Proto 3.0 powered units powered by 2 Z1000's and 1 Z500 ( 1 to each oval).  I've done 2 the last few years.  Are three possible?  I just noticed today that I have 2 fixed and 2 variable inputs.  I've been using fixed for the Z units.  How do I run the 3rd?   The issues I've had is that a derailed train would pop a breaker on one of the Z power units and a brand new MTH CTA subway set just stopped after less than 5 runs around the tannenbaum (out of warranty $330)  Many years ago I had a Proto Sound MTH E8 ABA unit snap, crackle, and pop!  I had it repaired and changed to a 2.0 with no issues.  I just got another $1000+ MTH set up, and want to prevent owning another paperweight.  My TIU is level "L" if that matters.  If running three trains under a tree require wiring that resembles the cockpit of a 727 with the panels removed, then I'm going back to conventional.  Most of my friends drink enough not to appreciate the difference between a first year Lionel Polar Express/1936 AF Zephyr vs. a MTH Premier NYC Hudson.  BTW, I'm running O48 Lionel Fastrack due to space limitations.  My MTH Premiers can run, but they look goofy/odd/wrong on O48.  I just got a MTH Railking Imperial GS-4 SP with all the passenger cars with the happy Christmas Lights figuring this is the last shot due to MTH shutting down.  2020 continues to be a dog with fleas! 

I'm assuming all three loops are independent and not electrically connected.

You should have trans A connected to Fixed 1 In and then out to one loop from Fixed 1 Out and then trans B connected to Fixed 2 In and then out to the second loop from Fixed 2 Out.

In order to run a third command loop, change Variable 1 to a fixed channel using the remote. Then connect Trans C to that Variable (now Fixed( input and then out to the third loop.

Now each track should run DCS independent of the others and you should not have any electrical issues, unless you are frequently derailing for some reason, but that's operator error, and should not be happening in a properly set-up layout.   

As for the TVS diodes. You can get them on amazon or ebay. They stop a large voltage spike from taking out your control boards if any wheels jump the track, and they are very easy to install. They come with different ratings, so here's my recommendation. I also install a fast blow fuse in the wiring.
Only one locomotive at a time on each track:
1.5KE27CA on each output

For a lashup or double heading locomotives:
1.5KE30CA on any wires going to a track where you run multiple locomotives at the same time.

For a fuse size, the DCS Wifi companion recommends 10 amp. I've seen those not blow with only one locomotive. So I use a 7 to 8 amp amp for those situations.
Here's a fuse holder. I didn't link the kits with holders and fuses as they use 18 to 22 awg wire, which is too small for the current drawn by the locomotives.

Here are the fuses. You actually spend less money per 10 and 7 or 8 amp fuses buying them in a mixed assortment than buying a package with only 10 or 7/8 amp fuses:

I used automotive fuses at first but am switching to the glass.

All you need for tools are some strippers, crimpers (cheap ones are fine),  butt splices and electrical tape. You can get fancier with heat shrink and soldering things if you want, but that's a personal choice.

On the Christmas layout, I use an old RW transformer  for the power. Since I'm paranoid, I put a TVS diode and fuse on the TIU input. For the power on the  layout I'm working on I use an old Z, so I still use the diode and fuse.

The diodes can be installed on the barrels for the TIU input and track connector. The fuses are installed before the diodes because, as soon as the over voltage is gone, the diodes will stop current flow and power will be re-apllied to the track, Then they'll short again and so on. It' almost like the old breaker on my RW.

With the fuses where they are, it protects the transformer, TIU in and out, the TVS diodes, and the control boards on your locomotives. I did this for My DCS Explorer too before I upgraded to the full blown Wifi setup.


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Last edited by Quietman

BTW, if you are using any locomotive with a digital control board and are running it directly from a transformer in conventional mode, you should still use  the fuse and TVS to the track.

As for breakers. There's a HUGE time difference between a fast acting fuse and some of the so called, fast acting breakers as most are tripped thermally. They are fast acting when it comes to protecting equipment from over current that is not digital, hence they can use the term. The exception is electronic breakers that actually monitor the current, but those are not cheap. What it says on the breaker and how it actually reacts are not the same. I spent some time looking at the trip curves from the manufacturers on a number of breakers people recommend. The time it takes for a breaker to trip is highly dependent on how far over the breaker rating the current goes. I did not like the variability.  They can be dog slow compared to a fuse, depending on the circumstances. The TVS may compensate for that as, when it creates an effective short, the breaker may instantaneously trip. Just got a digital o'scope, so I'm going to get a breaker and see what happens using a TVS diode and breaker from the old RW, when I make an old post war Lionel loco jump the track. (That way I don't have to worry about frying any boards)

Last edited by Quietman

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