# ZW at risk



## cos1953 (Nov 16, 2015)

I have a ping-pong table filled with O27 track and ten switches, more a maze than a railroad (but the grand kids love it). I got a deal on O gauge track and want to add a mainline around the outside of the maze powered by the second side of my ZW. If both sides were powered on and a derailment crossed from one track the other, what would happen to the transformer? Thank you for your time and consideration.


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## sjm9911 (Dec 20, 2012)

It would short out. I don't think it would be any diffrent if it derails on one track. There is always a chance of damage with anything. If your are using newer stuff with circuit boards, you need diffrent protection. ( this would be best case with one or 2 loops)


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## phillyreading (Aug 25, 2015)

When metal touches metal if it is the center rail to an outside rail it should short out. How long it takes to trip the circuit breaker depends on what model ZW you have. The old post war ZW's circuit breaker takes about 3 to 5 seconds to trip with a direct short. The newer ZW-c and ZW-L should trip almost instantly and have TVS protection built in.

If you are using a post war ZW you can add in 7 or 8 amp circuit breakers in line to help with circuit protection. The breaker in a post war ZW is there to protect the transformer and not the equipment run. Another decent thing to do is to add TVS(transient voltage suppressor) units to a post war transformer when using newer engines with circuit boards so you don't fry the circuit board.

Lee Fritz


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## BigAl56 (Dec 14, 2011)

Any time center rail shorts to outer rail it can cause damage and trip the circuit breaker.
The circuit breaker in the ZW is designed mostly to protect the transformer. To protect the trains and layout Philly is right and wiring in a 7 amp breaker is best practice.


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## RonthePirate (Sep 9, 2015)

Not hijacking the thread, but I have the same question, but for a CW-80.
It's not newer, (no date) made in China is the only clue to a time.
Would that also need a breaker?


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## cos1953 (Nov 16, 2015)

Thanks for the information - what does a 7 amp circuit breaker look like and where can I get some?


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## Lehigh74 (Sep 25, 2015)

I would try Digikey. They charge reasonable shipping fees and they are QUICK. You might want to go with a 10 amp as there are more to chose from, but you can do a search for whatever you want. You need one breaker for each track. I went with the SNAPAK 10 amp push pull.

http://www.digikey.com/product-sear...=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25


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## Wood (Jun 9, 2015)

This may be a little overkill however it is effective, easy to operate and trust worthy. From DelCity see the link:

http://www.delcity.net/store/Thermal-Push-Button-Circuit-Breakers/p_539615.h_539678.t_1

It is a 10 amp small circuit breaker. They are $4.51 each and you can mount them to your transformer station or you can get the mounting box which is a little expensive at $49.47. 

Each of my power supplies runs through these breakers before going to the layout so I get an immediate trip when ever a short circuit occurs.


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## phillyreading (Aug 25, 2015)

I got my circuit breakers from Mouser Electronics a few years ago. They look like the ones Scott's Odds & Ends sells in a set of 4 but cost way less then Scott's.

Lee Fritz


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## 400E Blue Comet (Jul 11, 2014)

Hmm... An interesting question. It would probably short out both track power coils in the ZW, but that's given that it crashes in such a manner that would touch the correct combinations of rails between them. Even if you did get it to do that, it would most likely not be harmed. When I encounter see a spark from a crashed train or when I'm using a bad track when using my KW, I instantly turn it off and there's no harm done. However if you leave the short there without turning it off, you'll obviously be tempting fate but it's doubtful you'll leave it like that without noticing. Another thing to remember, in order for damage to occur the transformer must get hot enough for the insulation to melt first, so you'll probably be able to stop the transformer in time. Most big lionel transformers have circuit breakers anyway.


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## sjm9911 (Dec 20, 2012)

Any auto parts store will have an inline breaker. But like I said if not running anything new its probably not nessaccery. As for the CW 80, the newer transformers have faster breakers, so its probably all good. I do remember some of the CW 80 were not as reliable as others. But I dont think it was because of the breaker. Some were built cheaply and had some problems.


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## phillyreading (Aug 25, 2015)

400E Blue Comet said:


> Hmm... An interesting question. It would probably short out both track power coils in the ZW, but that's given that it crashes in such a manner that would touch the correct combinations of rails between them. Even if you did get it to do that, it would most likely not be harmed. When I encounter see a spark from a crashed train or when I'm using a bad track when using my KW, I instantly turn it off and there's no harm done. However if you leave the short there without turning it off, you'll obviously be tempting fate but it's doubtful you'll leave it like that without noticing. Another thing to remember, in order for damage to occur the transformer must get hot enough for the insulation to melt first, so you'll probably be able to stop the transformer in time. Most big lionel transformers have circuit breakers anyway.


True the Lionel transformers have a circuit breaker in them but it is a very high amp breaker, the post war versions; ZW has a 15 amp breaker hooked in on the common side, the KW has a 10 amp breaker and the Z has a 15 amp breaker. So you may fry something if used with newer engines without having additional circuit protection. Also a TVS or transient voltage suppressor works well with post war transformers as they won't clip momentary voltage spikes.

Lee Fritz


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## phillyreading (Aug 25, 2015)

I recommend using AC rated circuit breakers and not automotive circuit breakers. Car circuit breakers are used for DC and not AC and may trip prematurely or not at all because they are not set up for AC current. DC means direct current and/or battery voltage, AC means alternating current which can change polarity up to 60 times a second.

Lee Fritz


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## Wood (Jun 9, 2015)

Fritz, I never new that about the ZW being 15 amps. I'm glad you told us and that explains a lot. I'm glad I installed my 10 amp breakers and yes they are AC breakers.


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## sjm9911 (Dec 20, 2012)

More info here http://www.modeltrainforum.com/showthread.php?t=14195&page=5
Also, with the AC DC thing, some are made for both currents, I never even bothered to check, but I gave the specs that someone recommended to me. Ill double check it but im sure its fine.


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## gunrunnerjohn (Nov 10, 2010)

phillyreading said:


> I recommend using AC rated circuit breakers and not automotive circuit breakers. Car circuit breakers are used for DC and not AC and may trip prematurely or not at all because they are not set up for AC current. DC means direct current and/or battery voltage, AC means alternating current which can change polarity up to 60 times a second.
> 
> Lee Fritz


It shouldn't make any difference in the trip rating, these are all thermal breakers. They will all react to the RMS value of current flowing through them, be it AC or DC. However, the difference in voltage ratings between AC and DC switches and breakers is primarily due to the fact that 60hz AC will self-quench any arc upon opening as it reverses polarity every 8 milliseconds. This is typically not significant at the low voltages of the secondary of our transformers, but in higher voltage applications, the voltage specification becomes more significant.


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## DennyM (Jan 3, 2016)

RonthePirate said:


> Not hijacking the thread, but I have the same question, but for a CW-80.
> It's not newer, (no date) made in China is the only clue to a time.
> Would that also need a breaker?


CW-80 has built-in circuit breakers.


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## cos1953 (Nov 16, 2015)

Thank you all for your kind and informative replies. I have two circuit breakers ordered- have to protect the mother of all transformers.


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## Lehigh74 (Sep 25, 2015)

I don't think you have to worry about protecting the ZW. It can protect itself. It is not at risk. See attached manual that I downloaded from another thread here. What the circuit breakers you are adding (if they are similar to the ones that Wood, P&R and I added) will do is protect modern locomotives (with circuit boards). The breaker in the ZW is not fast enough to protect modern locos.

View attachment Lionel ZW User's Manual.pdf


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## David 1005 (Jul 1, 2012)

The issue with the postwar ZW that comes up from time to time is inadvertently connecting the variable throttles together when they are set at different voltages. This can happen when a loco or car with two rollers is left parked across an insulating pin. In order to use a single circuit breaker, Lionel put it in the "U" connections, not the variable voltage connections. This leaves a "short" line to line at different voltages completely unprotected. When the train is running and this condition exist only for a second it is not a problem. But if a train is parked over in insulated pin, which could exist for hours, the only protection is the house circuit breaker. Under this condition the ZW could be damaged or wiring on the layout could be be overheated.

To protect against this I suggest a 7 to 10 amp circuit breaker in each of the variable voltage outputs and a single 15 amp in the the "U" connections. Additionally, all the wiring on the layout should be of proper size to be protected by the circuit breakers. 

As for the current rating of the circuit breaker that comes with a postwar ZW, it is a thermal device. This type of device will usually have a graph that comes with them showing a current vs time curve. it will trip at 15 amps in some period of time. It will also trip at almost any other current depending on the trip time. A magnetic or electronic circuit breaker will trip almost instantaneously at the rated current, which is much more appropriate for toy trains.


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## DennyM (Jan 3, 2016)

When I had my post war ZW, I used 10A fuses I bought in bulk at the local Radio Shack here (yes there is actually one open in my little town). The fuses reacted immediately. Now I have a ZW-C so it's no longer a issue. I didn't know the breakers on a PW-ZW are connected to the U post.


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## sjm9911 (Dec 20, 2012)

OK good advice, I dont really know how parking a train across two tracks for hours would effect a transformer. Let alone why you would do it! I did park a train as a test across 2 different blocks a few years ago, one track with high voltage the other with low voltage and it seemed as if the higher voltage ran through the train over powering the lower voltage block. This was with post war, and some newer stuff but nothing with complex circuit boards. While im sure the zw can be damaged, I think its highly unlikely through normal use, if its been maintained. The trains however are a different story, the wires are smaller so I can see them being damaged more easily.


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## Wood (Jun 9, 2015)

> David 1005 Posted: To protect against this I suggest a 7 to 10 amp circuit breaker in each of the variable voltage outputs and a single 15 amp in the the "U" connections. Additionally, all the wiring on the layout should be of proper size to be protected by the circuit breakers.


Thanks David, I did link my circuit breakers to each variable voltage output. I did not protect the "U" ground connection however, I have an extra slot on my circuit board. All of my transformer's "U" connection are linked together. Why do you recommend a 15 amp breaker for that post?

I think I am going to experiment with your comment about creating a fault when a train is parked on two different Variable Voltage tracks. I have 4 different powered tracks using 2 ZWs that intersect each other and that could be a problem. I'll post my results later tonight.


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## DennyM (Jan 3, 2016)

Wood said:


> This may be a little overkill however it is effective, easy to operate and trust worthy. From DelCity see the link:
> 
> http://www.delcity.net/store/Thermal-Push-Button-Circuit-Breakers/p_539615.h_539678.t_1
> 
> ...


It's not overkill if it works for you.


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## Wood (Jun 9, 2015)

> David 1010 posted: But if a train is parked over in insulated pin, which could exist for hours, the only protection is the house circuit breaker.


David, I interpreted the above comment to say "..if a train is parked over an insulated pin (and it is shorting out).... the only protection is the house circuit breaker.

I experimented with this problem and by having circuit breakers on the variable voltage runs the problem does not exist. I put one end of a die cast flat car on one variable voltage track and the other end on the other variable voltage run. When shorting out the first end the breaker will pop in 2 seconds the same is true if you reverse the short to the other end and if both ends of the car are shorting out, both circuit breakers will pop within the 2 sec threshold. I also did this with the two variable voltage settings at different voltages.

So my conclusion is that circuit breakers on the variable voltage outlets are a complete fix for this problem.

Please let me know the answer to the 15 watt breaker for the "U" run.

As an aside, before I put circuit breakers on the ZWs I had a couple of shorts that melted some of my wiring. So I am reinforcing the effort for members to install some kind of variable voltage circuit breaker system on their ZWs.


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## RonthePirate (Sep 9, 2015)

DennyM said:


> CW-80 has built-in circuit breakers.


Just read this. Thanks, Denny! :smilie_daumenpos:


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## sjm9911 (Dec 20, 2012)

Some like the feel of the old school zws, plus the power is good for lots of stuff, the ability to run multiple trains , and have control over your accessories etc. Much better then being a few CW 80s. Especially if you get the CWs with the problems I have used 2 zws for my layout, I did add circuit protection for the newer stuff ( although I really run it) I also have a zw with 4 180 bricks that has built in circuit protection that will protect newer stuff. Its was $$$$ So, it could be the money factor too


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## David 1005 (Jul 1, 2012)

The reason I suggest a 15 amp breaker on the "U" post is that it is really just a single wire out put from the transformer. Inside the case all four terminal posts are connected together. If you use 7 amp circuit breakers on all four variable posts, A to D, and loaded them all to the full 7 amps, the load on the "U" post would be 28 amps. The maximum capacity of the ZW is 15 amps. The 15 amp external breaker on the "U" post is actually in series with the ZW own internal 15 amp circuit breaker. But that breaker is probably 60 years old now and I do not like to depend on it.


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## David 1005 (Jul 1, 2012)

When I referred to parking a train over an insulated pin, I am referring to a insulated pin in the center rail separating two different variable voltage terminals, like "A" and "D". A locomotive with two rollers or a passenger car with roller pick up on the trucks at both ends could shunt the center rail pin. If the two handles are set at different voltages this is shorting turns in the secondary coil of the transformer. If the voltage difference is great the current flow through the locomotive's pick up roller assembly or the passenger car's internal wiring will be limited only the the impedance of the transformer and the resistance of wire and track between the two transformer variable posts involved.


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## Wood (Jun 9, 2015)

David, Thanks, I got it. Very helpful comments. Besides the friendships I have made here this is the big reason I continue on the forum. There is always someone who has a lot more experience and knowledge and that helps me "do it right"!


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## gunrunnerjohn (Nov 10, 2010)

The PW-ZW does have a serious weakness in protection as has been pointed out in this thread. I always recommend anyone using them to provide circuit protection on each of the output terminals and not depend on the internal breaker.


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## Wood (Jun 9, 2015)

As a final follow up from me, my two ZWs now have "U" circuit breaker protection. My breaker box had two unused slots and I hooked each ZW up, individually, to their own 15 amp circuit breaker. Hopefully the system is now fully protected.


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## Ace24 (Nov 10, 2015)

There is Youtube video in which some Eaton circuit breakers are tested in line with a ZW. The tester concludes that 5A is too high, (a direct short does not trip the breaker), and that 3A is right.






The Eaton breaker he uses is now discontinued.
Is his conclusion correct in choosing 3A breakers? That's lower than what everyone here is using.


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## sjm9911 (Dec 20, 2012)

Honestly , I would trust the guys here. I watched the video the wire that burned up would probably do so anyway, as it was undersized. And mostly for post war stuff I dont see the need for extra protection. No computers or chips. And hopefully your watching your layout. I wouldn't leave it on unattended, so my zw would never cycle on , off, on, off. The 5 amp did not trip instantly, but it might have worked if left on the track for 2 seconds. You'll never know as it wasn't recorded


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## gunrunnerjohn (Nov 10, 2010)

FWIW, I have a 2A breaker on my test bench power supply. Other then when I have a real issue with a test subject, it never trips. Thermal breakers will carry a pretty massive overload for a short period of time.


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## Ace24 (Nov 10, 2015)

One more question:
If my ZW internal circuit breaker still works, is there any advantage to installing a ZW-232R replacement circuit breaker?

I plan to do what is suggested in this thread and put external circuit breakers between the transformer and the track/accessories. But I'm curious, is installing a ZW-232R just for when the original circuit breaker is shot, or does it perform quicker and better than the original?


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## gunrunnerjohn (Nov 10, 2010)

I would install external circuit protection and leave the original ZW breaker intact.


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