postwar ZW replacement circuit breakers

[lionelsoni]

"If you're counting on 14 AWG or larger to reduce voltage drop, you can't take advantage of these lower breaker ratings."  I didn't say that you can't use a 5-ampere breaker.  You just don't get the advantage of using smaller wire--cheaper and easier to work with--because you're still using 14 AWG for another reason, that is, its lower resistance.

[phillyreading]

The logic is that you can safely use 14 gauge wire on a 5 amp circuit, what Bob N. is talking about is voltage drop or resistance of the wire to the number of feet it is away from the power source-transformer. Since 5 amps is only one third of the rated capacity of 14 gauge wire, according to the NEC(National Electric Code).

[cwburfle]

Although protecting against faults between the multiple outputs of a transformer is the primary reason for adding individual breakers, using breakers with lower ratings has another benefit.  Since any one circuit is very unlikely to need the full 15 amperes that a ZW or a Z can put out, using breakers rated somewhere between 5 and 10 amperes (depending on the needs of your trains) makes it completely safe to use smaller than the 14 AWG wire that 15 amperes requires.  For example, 16 AWG is big enough for 10 amperes, and 20 AWG is big enough for 5 amperes.  Of course, if you're counting on 14 AWG or larger to reduce voltage drop, you can't take advantage of these lower breaker ratings.

 

I just don't follow your logic. If you wire with 14 gauge, you cannot use a 5 amp breaker? Why not?

There is more to protect than the wires under the layout. How about the wires inside the trains and acessories? A lot of the internal wires in Postwar Lionel are 20 to 24 gauge.
Then there is personal safety.
I recall an incident where a steam locomotive derailed, and the wire handrails happened to short across the tracks. That handrail got hot enough to cause a rather unpleasant burn, but all the feed wires and the transformer were fine.  Imagine a child grabbing that engine. Do you think he or she would be real anxious to play with the trains anytime soon?

[lionelsoni]

I agree that fuses are a nuisance.  And, although they and electromagnetic breakers are not at all unsafe, they do not do a good job of modeling the windings and wiring that they are protecting.  A moderate momentary overcurrent is not really dangerous, since it takes time to heat up the wiring to the point of damaging it.  Thermal circuit breakers, the type that Lionel used and the type that is used in automobiles, do a good job of opening the circuit only when the wiring is truly in danger.

Although protecting against faults between the multiple outputs of a transformer is the primary reason for adding individual breakers, using breakers with lower ratings has another benefit.  Since any one circuit is very unlikely to need the full 15 amperes that a ZW or a Z can put out, using breakers rated somewhere between 5 and 10 amperes (depending on the needs of your trains) makes it completely safe to use smaller than the 14 AWG wire that 15 amperes requires.  For example, 16 AWG is big enough for 10 amperes, and 20 AWG is big enough for 5 amperes.  Of course, if you're counting on 14 AWG or larger to reduce voltage drop, you can't take advantage of these lower breaker ratings.

[phillyreading]

I have added 10 amp breakers to the outputs of my 275 watt ZW, for a total of four circuit breakers. Like others have mentioned, the ZW does not have good circuit protection between outputs A to D, the only thing protected by the factory is the common side as this is where the circuit breaker is really protecting. You might want to use 8 amp breakers if you can find them, as I feel this would be better then the 10 amp breaker that I am using. I don't use fuses as they have to be replaced anytime they blow.

[cwburfle]

The internal circuit breaker in a ZW is only designed to protect the transformer, and does not do a thorough at that.
A circut can easily be created between any two "hot" posts, (A,B,C, or D) which is not protected by the breaker. For example, this could be done by a locomotive pickup assembly bridging two blocks controled by different handles.
Additionally, a ZW breaker will not trip unless heavy amperage is flowing. According to the test bench section of the Lionel factory service manual, a good ZW breaker should trip in 11-40 seconds under a thirty amp load.

Therefore, it is always a good idea to put external circuit breakers on each "hot" post of the ZW. Same goes for the KW.
I like to use Lionel postwar #91 adjustable electromagnetic breakers. They trip instantly.
There are many other options.

[TrainLarry]

  If the ratings are the same, then the choice is yours. I have the Z-22 because that is what I could get at the time I needed to replace it.

 You do not need to add an external circuit breaker to protect the electronics, but a Transient Voltage Suppressor (TVS) such as this.

Larry

[Mr. S.]

Hello!

What is the the preferred replacement circuit breaker for an ZW I'm bringing back up to speed with new carbon rollers, updated diodes and a circuit breaker.

Would it be the Z-22 that mounts in the bottom of the case, or the gray updated circuit breaker (ZW-232) that mounts where the old one would have (I don't know the ratings but I see them all the time).

Thanks!

 

p.s.  I should add I run almost all conventional but do have two TMCC Lionel engines but have not yet made the jump to command control but will someday.  No layout at the moment.  I understand I might want to add an external circuit breaker at some point to protect the electronics of the TMCC engines when I upgrade my power.