SSPRR Run Room

Playing with Toy Trains

Toy Train Layout Wiring - Engine Safety Relays

Basic Intermediate Advanced Wire Management Bus Wiring 120V Train Room
Glossary Wire Sizes Switches Load Calculations Soldering Troubleshooting


Bridges Wired to Control Track Power
with Relays for Engine Protection

see Lionel postwar 316 Lift Bridge with 022 Turnout Protection

When an access bridge can't switch the track power, the bridge can switch a relay.

Run Room Wire Color Coding

Black and Red #12 for outside Main Tracks Variable Voltage, White for all Commons,
Red #16 for Z-Stuff Switch Machines

Lift Bridge with Lift Assist Serving the Two Main Lines
(located at South end of Run Room)


Atlas 2 Track Truss Bridge

Atlas O 3 Rail Double Track Pratt Truss Bridge Kit

Atlas 2 Track Bridge Open Atlas Two Track Bridge Table Contackt
The bridge acts as a switch for the Common
that trips the 2 relays for the two isolated area
center rails.  The protected track is long enough
to prevent an engine from running into hole.

Bridge Track Power Soldered
Wires are soldered to bridge track.

See Access Bridges used as Switches

Wiring Bus for Black and Red Mains with Z-Stuff DZ-1008 Relays
The Black track is the outside Main, the Red track is the inside Main, and the Purple wires are
for switched track.  The white wires are Run Room commons.  The "gizmo" at the
bottom left of the photo is an original MTH DCS Filter.

Protected Track Relays and Wiring


Z-Stuff for Trains DZ-1008 SPDT Relay Module
(used as a stand alone relay - Requires 10-18 VAC, Relay Contacts rated 10A 24VAC)
Wiring for Engine Protection with Open Bridge

Relay Wire Color Function Function for Engine Protection with Isolated Center Rail
12-14 VAC
tie to RED
not used
Relay - COM
Relay-NC (not used)
Relay - NO
Red 13 VAC terminal for Z-Stuff Switch Machines
White (outside rails)
Red 13 VAC terminal for Z-Stuff Switch Machines

Red or Blue Variable voltage power from Control Center

Purple to center rail (off when bridge is open)

Lift Bridge with Lift Assist Serving the Outside Main Line
(located at North end of Run Room)

This bridge needs two circuits to prevent an
engine running into an open hole.  With the
bridge closed the straight path and curved
path through the turnout are both live.  With
the bridge open and the turnout lined for the
 straight path, the protected track is dead.
With the bridge open the turnout lined for the
curved path, the protected track is live.
Single Track Lift Bridge
Lift Bridge Open

Protected Center Rail Through the Turnout
The rail between the turnout and bridge opening is too short to keep an engine from
coasting into the hole so the protected track had to extend north of the turnout.

Protected Center Rail Diagram


Wires into South Table The black and white wires to the left feed the
bridge rails.  The black wire is the live feed
from the north table.  They slide into the table
holes when the bridge is lowered.

The bridge is fed by the same wires
soldered to the track.
Soldered Wires to Rails
When the bridge is lowered, the copper strip
on the far side connects the Commons/White.
The wide copper strip on the near side acts as
Bridge North End Contacts
a switch by closing the circuit between the black
center rail voltage and the purple switched
North Table Bridge Contacts

Z1008 Relay Plugged into Switch Machine


Terminal Strip w Risistors Terminal Strip w Filter

From Z-Stuff for Trains - The diodes must be added to prevent early drop-out when switch motor is wired for non-derailing operation.

Z-Stuff Diode Diagram

This diagram is posted at titled "DZ-1000 & 1008 Non-Derailing Operation With DZ-1008 Track Power Control".


This Z-Stuff Relay Diagram is Posted Near Relay for Reference
For Track Protection Zone:
Blue Com wire goes to Black center rail variable voltage source.
Gray NC wire is not used.
White NO wire goes to Purple Switched center rail.
Yellow Relay wire ties to Red Switching Rail for Straight Path.
  Green Relay wire ties to Green Switching Rail for Curved Path.
Red Relay wire ties to Red 13 VAC terminal for Z-Stuff Switch Machines.
Black Relay wire ties to track White Common

Z-Stuff Relay Wiring Diagram


Question? Contact the SSPRR COO (Chief Operating Officer) using the email button to the right.  (If email link is absent, please enable JavaScript.)