Does the MTH Z-4000 require additional circuit breakers

I am a big fan of the PSX-AC. When placed between the track and TIU (or power source), it protects everything against derailment voltage spikes and amperage overload. One for each throttle.

Add the piezo chirper to provide an audible notification of a short circuit.

https://tonystrains.com/produc...gent-circuit-breaker

@hclark6345 posted:

I am using 7 amp circuit breakers on the individual output posts between my Lionel ZW and the track.

Does the MTH Z-4000 need the same level of circuit breakers between the output posts and the tracks?

I also am using 7 amp (thermal) breakers on my ZW and also on the Z-4000. Those external breakers to the Z4000 always seem to "pop" before the internal ones so I'm pleased to have them. But while I regard the external breakers on the ZW to be an absolute necessity,  the ones on the Z-4000 are more of a nice-to-have. (The only exception to the breaker type is when I run the Lionel Acela set where I need to use the fast-acting Airpax/Sensata breaker to instantly kill power to the engines in a derailment.)

The Z4000 breaker is a couple orders of magnitude faster than any thermal breaker but rated for ten amps. You only need another breaker if you want to limit current to something less than ten amps.

Pete

Thank you all for your replies. I will go with the 7 amp breakers. It seems to be kind of a " belts and suspenders " solution,  but will give me a little more peace of mind.

I bought 2 brand-new Z4Ks a few years ago, and it has been my experience that the breakers on the fixed outputs are lightning-fast, but very slow on the variable outputs. I contacted MTH about this shortly after I bought them, spoke to Don, and he said that is normal operation. I never understood why a modern transformer like the Z4K doesn't have fast-acting breakers, asked several times, but never got an explanation, so I quit asking. I was expecting fast-acting breakers like the one in the Lionel 180-watt brick.

They're usually sufficient and way faster than the breakers of old. However, we switched over to PSX-AC breakers as they're even faster, plus they will auto-reset.

My board melting derailment was powered by a Z4K.  Bought a batch of Airpax instant trip breakers after that.