@nkptomo posted:I have an old TIU. no fuses. Z100 transformer.A Scotts 15 amp circuit breaker. Where do I put the breaker?
Your Scotts 15A circuit breaker is NOT useful in the context of this situation. 15A rating it will never trip and never protect anything. Use it as a door stop, a paperweight, but nowhere with your trains.
Your power source, a Z100 (assuming you mean an MTH Z1000?) already has a 6A thermal circuit breaker in the side.