Legacy with old ZW - Any need for 10 Amp Bkr

Your Legacy command base is pretty safe, it doesn't actually have any current flowing through it from the transformer.  The track connection is capacitor isolated in the command base.

The danger from old PW transformers comes to the stuff on the tracks, that's why you add the breakers and possibly the TVS as well.

I am pretty sure my JLC BigBoy fried a board when it derailed while on a track connected to my old postwar ZW. Luckily it was still under warranty

I can believe that, protecting stuff on the track is the point of the breakers, the Legacy base is pretty safe for the most part.

I'm guessing that he is thinking about the Legacy electronics in the engines. If so, use this on each of your track circuits...

http://www.tonystrains.com/pro...s/dccspecialties.htm

scroll down to this...

PSX1-AC 3

He clearly states he is worried about the Legacy 990.  So John's advice was correct.  Dave pushes the Scott's resettable breakers and uses DCS so the track power goes through the TIU.  Legacy and TMCC for that matter don't have current flow through the device to get to the track.  G

I disagree. The breakers are to protect the transformer/power supply and wiring to the track. The damage to the stuff on the track is already done(and it's cumulative) long before the fastest breakers trip.

Well, that clearly depends.  If you're talking about voltage spikes, that's true.  However, in a derailment, I'd like a breaker to trip rather than the locomotive wheels to sit on the track arcing because there is no circuit protection.

Circuit breakers are just one element of equipment protection, I think we've covered that many times.

While I have you gentlemen's attention, I'm a victim of 3 separate incidents where the train derailed and before I knew it I was melting and cooking wire with my Lionel ZW.  I have since gotten a spool of 14 gauge wire and will put that into effect soon.  In reference to the breakers, how do I wire that into the layout?  Is it between the track and the transformer, and I also have a ZW-L.  Will I have to worry about this derailment problem when I use that transformer also?

The breaker would be between the transformer and the track connection.  While a 10A is fine, for added protection I'd probably consider something like a 6A model.  It'll withstand brief peaks of more than 6A, but on a true derailment it'll trip a lot faster than the 10A model.

I use the PSX-AC breakers cjack posted above with my PH-180 bricks. They are probably the fastest available for our trains, faster than the PH-180's which are very fast. IMHO, those would be well worth looking into. The small modern breakers sold by Digi-Key (and other places) would protect your wire from melting. Others may disagree, but personally I would not trust the breakers in the PW-ZW's and would add some other type of protection no matter what I was using it for.

I thought the ZW-L had excellent breakers for protection, but according to the manual with a short on the track, it first drops the voltage to maintain 10 amps current and can then take 3 seconds to trip the breaker. 3 seconds sounds like a lot to me, but someone better versed in electronics would need to weigh in on the whole process for an explanation and any damage that could occur while waiting the 3 seconds. Maybe one of the other more knowledgeable folks in this thread will be back with more on this one.

I know that voltage spikes are a big cause of bad electronic boards and the PSX-AC above protects against those as well. TVS diodes are also recommended a lot around here for voltage spikes. That would also be a very good addition to everything else mentioned here for protection. I would rather over protect than under protect when it comes to replacing $300-$500 and up engines or $200-$300 worth of electronic boards. Or as a good friend of mine says "anything worth doin' is worth over doin'"

Gentlemen,

    When I use the DCS and the Legacy together the TIU has the built in TVS and I use the Scott 10 Amp resettable breakers between the old ZW & KW's, heck I even have them in front of my Z4K, I do believe I will put one between the ZW and the track as I test the Legacy buy itself, it's probably over kill, but I have nothing to loose in playing it safer.  I have been using the 10 Amp Scoot breakers as G points out, with my DCS for many many years, I might do as Guns says and pick up a bank of 6 Ampers, I do believe the company who bought Scotts out, still has the 6's, but the 5's and the 7's have been discontinued.  In the post above I was mostly concerned about the Legacy 990, however with as expensive as some of these Legacy engines happen to be, that also is a big concern.  Because the Legacy is so new to me, I wanted to test it by itself,

before I integrated it into my DCS where I have all the safety breakers already available.  With as long as I had to wait for my 990 legacy I do not want it damaged.

PCRR/Dave