The 5F circuit breaker test for the ZW transformer places a .1 ohm (one tenth) resistor across the output terminals of the transformer.
With this load, the 5F manual says the current should be 30 amps (thirty), and the circuit breaker should take between 11 and 40 seconds to trip.
IMHO that is a lot of current, and an awfully long time, which is one of the reasons I aways use postwar Lionel #91 adjustable electromagnetic breakers on all the power posts that are in use.
The internal breaker is there to protect the transformer. It probably would not protect your wiring or anything else very well.
The resistance load in a Lionel test bench is a heavy piece of nichrome ribbon. They get HOT!
I absolutely would not use a postwar Lionel ZW transformer that did not have a properly working circuit breaker.
