Well, I can't help with the ZW-L, I don't own one. However, the ZW-L should normally not trip the thermal breaker, doesn't it have fold-back current limiting?
Your Lionel ZW-L is equipped with three levels of overload protection: dynamic power limiting, foldback
current limit, and circuit breakers. Each output has its own fold-back current limit and circuit
breaker. The dynamic power limiting is applied across all four outputs. This provides multi-layer protection
for your trains and transformer while supplying the maximum power possible for pulling lighted cars or
fighting over grades with heavy loads.
And their take on the actual physical circuit breakers, seems they assume the electronic current limiting will deal with most overloads.
The circuit breakers on the ZW-L Transformer are designed as a fail-safe for the electronic over-current
protection. Because most problems will be protected by and corrected during fold-back mode operation
(described in the previous section), circuit breakers should be tripped infrequently.
Seems like a power cycle would cure 90% of the ZW-L overload issues as well.
