I thought I’d post this info for anyone else who might find it useful.
A few months ago I purchased a new 6-85226 180 watt powerhouse from an authorized Lionel dealer. I intended to use it to provide power to a fixed channel on my TIU. Upon receiving it, to my great frustration, the circuit breaker would trip as soon as I turned it on EVERY TIME. I eliminated all the variables until I realized that The powerhouse didn’t even have to be connected to anything for the breaker to trip!
I was in the verge of returning it when I decided to stick both of the leads from my voltmeter into the molex connector plug and noticed it was registering high and low readings. Eventually, I decided to role up some electrical tape and put it in the molex plug hole that is “empty”, I.e. the hole that doesn’t have the connection through which the power would pass. Low and behold, the breaker stopped tripping when I would turn it on and it has both provided power and the circuit breaker has worked appropriately ever since.
I have no idea why this occurred and unfortunatetly have forgot what caused me to think to put the electrical tape in the top hole but it has essentially served to fully/properly insulate something in the plug. Hope this solution may be prove useful to anyone else who may encounter this problem.