Adding a "brick"??

Hi Mannyrock,  Good questions.  So that I can hopefully avoid confusion, I'm going to use the terms used by MTH in describing their Z-1000.

The Z-1000 transformer is what is often referred to as a "brick".  Lionel's Powerhouse 135 and 180 transformers are also called bricks as are the Z-500 and Z-750.

The Z-1000 transformer has two outputs.  One is a 2 conductor barrel connector that puts out a constant 18VAC and connects to the Z-Controller's input.  The Z-Controller chops up the incoming 18VAC into tiny on/off slices spread out over small time increments and puts out an 18VAC or less average voltage depending on the throttle position.  The second set of outputs from the Z-1000 are a fixed 14VAC, which is designated for Accessories.  The Z-controller's input is designed to only have one Z-1000 transformer connected to it.

If one wanted to add another brick or any type of transformer to their layout to increase the amount of power that can be delivered for more trains and/or accessories, there are essentially two ways to do this.  One way would be to keep all the connections from different transformers separate, i.e. no common neutral (ground), neutrals not tied together.  This would require all tracks, wiring, and accessories fed by different transformers (bricks) to be kept completely isolated electrically.  For most 3 rail O gauge layouts, the preferred way to use multiple transformers, especially when using conventional throttle control of multiple trains on different interconnected tracks is to have a single neutral bus that's common to all transformers and all outer rails.  Only the Hot wires from different transformers would be connected to the center rails of different track sections (called Power districts or blocks) which have their center rails isolated from each other.  This isolation is accomplished by using either fibre pins with traditional tubular track, by cutting the center rail, or by using special track sections which already have a gap in the center rail.  When using multiple transformers in this way (common Neutral), the transformers must be in phase with each other, AKA. Phased.  Phasing assures that the maximum continuous voltage that is ever present on the tracks is ~18VAC or less.  With unphased transformers, voltages can reach up to 36 or more volts.

There are numerous topics on phasing multiple transformers here on the forum.

Excellent reply Steve.

Thanks very much,

Mannyrock