I used Wireless switches to turn off the entire layout and also to be able to power cycle individual transformers. As a final warning, I have a nice bright red light that tells me that the layout is on.
I have four of these remotes that are scattered around the layout, the four transformers are on the first four buttons, the 5th button is the master off for the entire layout. I normally stick one of these in my pocket when I'm running so I have instant control of the layout power at any time.
The receivers here are for each of the PowerHouse 180 transformers. If I need to reset the breaker for an individual power district, I can cycle just that transformer from anywhere in the room.
This receiver turns off all the power to the layout.
Up on the wall I have an additional receiver with an LED bulb that is slaved to the main power, whenever the power is on, that bulb is on. This alerts me to the fact that the layout is on if I'm leaving and forgot to turn it off.
