4 Small Layout Wiring

Part 8 Section 4 LAYOUT WIRING Issue Date November 1997

4 Small Layout Wiring Although it is possible to connect the feed and return wires directly to the track, it is preferable to 4.1 General use fine wire droppers to connect the rails to terminations under the baseboard. Tinned copper wire of For a newcomer to layout wiring, being presented about 24 SWG is a useful size which when painted with a full layout wiring diagram can create a false with track colour virtually disappears into the back- impression of the complexity of the work involved. ground. The terminations under the baseboard can The majority of layouts, particularly the smaller be a 'chocolate block' screw connector or a soldered terminus to fiddle yard variety, normally consist of connection. If a layout has to be set up for each a series of simple individual circuits. If these are operating session and dismantled afterwards, the tackled in a step by step manner the final result latter method is preferred as screw connectors have should be achieved with the minimum of fuss. been known to loosen due to constant movement. Before wiring commences, at least one of the fol- Intermittent faults due to a loose connection can be lowing items of equipment should be acquired to difficult to trace. A simple dropper terminating at a enable each circuit to be checked: a VOM (Volt-Ohm brass brad is shown in Figure 4-1. Whichever Meter) or multi-meter having a resistance setting method is used, leave a little slack in the dropper to which is used for checking continuity and/or a sim- allow for movements in the rails due to temperature ple continuity tester consisting of a box containing a or humidity changes. For the same reason, where battery and buzzer and having a range of probe electrical breaks occur in the rails, they should be wires. The multi-meter need not be an expensive prevented from closing up by filling the gap using type as it does not need to have a high degree of either an insulating fishplate, a thin slip of plas- accuracy. A multi-meter and a home made continu- tikard or some epoxy resin. This will also make the ity tester are shown in Photo 4.1. Points to note are joint smoother for rolling stock to pass over. that the wires for the continuity tester have small Once droppers have been installed and tested, crocodile clips at the end instead of probes and that an identifying letter and number should be marked the third is extra long to enable the tester to span underneath the baseboard adjacent to the terminal. the length of a baseboard or to reach from a termi- Figure 4-1b shows the local connections to a tie-bar nal below the baseboard to the track above. The operated microswitch, mounted below the base- buzzer type of continuity tester is particularly use- board, which is used to change the polarity of the ful for checking wiring over a distance as it allows crossing or frog when the turnout is moved. In this the operator to hear if a circuit is complete. case, the identifiers have been chosen to reflect the purpose of the dropper.

a) b)

P1F

Tie-bar Operated a) Simple wire dropper attached to a brass Microswitch P1X screw or brad. b) View of the underside of a baseboard P1C showing the connections to a tie-bar operated microswitch. The numbering system adopted is: P1f - Turnout 1 Feed c) Isolating Switch Adjacent Rail Rail, P1c - Turnout 1 Common Return Rail and P1x - Turnout 1 Crossing or Frog Isolating Rail c) Isolating rail used to stable an engine or, if the track is long enough, a multiple-unit train. The isolating switch can be located at a convenient spot, either at the edge of the baseboard or on a separate control panel Return Rail FIGURE 4-1

Compiled by K. Sheale. 8 - 4 - 1 PHOTO 4.1 An inexpensive multi-meter and a continuity tester for checking layout wiring.

Note: Because the rail polarity changes with the 4.2 A Simple Loop Terminus. direction of movement of the locomotive, the use of the terms positive rail and negative Because of the wide variety of layout designs and rail can be confusing. Hence the preference operating requirements, there are no precise rules for the terms (power) Feed and (power) for wiring layouts. However, unless the layout is a Return rails to identify them. simple through station without a need to reverse trains, the majority will require some form of loop to Examples of other identifiers used in the follow- enable the locomotive to run round its train. Basic ing sections include F for a power Feed, SF for a loop wiring, the power feeds and the electrical Switched power Feed, CR for a connection to the breaks required are dealt with in Section 3, Point Common Return and IR for an Isolating Rail used Wiring (subsection 3.3.2). Figure 4-2 shows a termi- to stable an engine. An example of the latter is nus having a loop to release the locomotive plus two shown in Figure 4-1c. With careful use of identifiers spurs, one serving as an engine service road. If the at each end of a circuit, the wiring between the pointwork were of the insulated frog type, e.g. Lima droppers and the power supply or isolating switches set-track, only two wires would be required to sup- can use a single colour cable. However, if the layout ply power. As most layouts use some form of live wiring is to be worked on by a group, it is useful to frog pointwork (see also Section 3, Figures 3-2 and arrange a standard colour coding system to assist 3-6), additional feeds and insulation breaks are members, particular when tracing faults. For exam- needed. Figure 4-2 shows the connections required. ple, a coding system could use Red for Power Feed, The electrical breaks in both rails which occur in Black for Common Return and Blue for Isolating the middle of the two crossovers divide the layout Rails. Cables are available in a range of colours, into two main areas. The single break in the plat- both plain and two-colour banded form road common return rail is to prevent a short As the majority of layouts use 2-rail electrifica- circuit occurring when one of the crossovers is tion, this is dealt with initially, 3-rail - stud contact reversed. (see also Section 3, subsection 3.3). electrification is covered in subsection 4.7. In order to make wiring and the subsequent testing as easy as possible, a convention should be established to assist in identifying which rails are feed rails and which are return rails. As an exam-

8 - 4 - 2 Part 8 Section 4 LAYOUT WIRING Issue Date November 1997

Platform

Engine Spur Main Line

Release Road Spur Release Road Engine Service Road

b) Point 1a Point 2a F2 Loop Break F1

CR F3 CR Point 1b Point 2b

1b xing 1b return 1b feed

c) a) Basic track diagram of the type appearing in the model press. F3 F1 F2 b) The same diagram expanded to show the individual rails with insulation breaks marked. The loop CR CR CR break (marked) is to prevent a short circuit when one of the cross-overs is reversed (see also Figure Connection to 3-8a and b in the previous section). The turnout Baseboard operated switch shown worked by turnout P1b changes the polarity of the frog. Similar switches would be fitted to the other three turnouts on the Control Unit diagram.

c) Simple wiring schematic showing feed and return connections. FIGURE 4-2

ple, in an oval layout the outer rails of the track could include the engine spur at the end of the plat- could be the feed rails and the inner rails the return form road, the release road spur and the engine ser- rails. Once a convention is established, stick to it. In vice road. If the latter were long enough it could Figure 4-2 the upper rails are feed rails and the provide two stabling spots. These require additional lower rails form the return. The identifying num- electrical breaks in one of the two running rails at bers shown on the diagram represent the droppers these locations. Although either rail can be used, it supplying power to the track and are marked on the is preferable to put the break in the feed rail and underside of the baseboard adjacent to the dropper leave all the return rails linked together electrically terminations. If the layout has only one loco in ser- to form the common return. (See Figure 4-1c) vice at a time and is served by a single control unit, The additional electrical breaks are shown cir- the wiring schematic, shown as an inset, is all that cled in Figure 4-3 and the connections are given is required. identification codes. Note that because the feeds to If more than one engine is present on the layout the release road spur and engine service road are on it becomes necessary to provide isolating rails the same side as the frogs of the adjacent turnouts, where the additional engines can be stabled. These they could be fed directly from the controller but the

8 - 4 - 3 preferred method is from the crossing connection of connections to the droppers on the baseboard would the adjacent turnout. The connections shown with require a multi-cable connection to be fitted. Figure the suffix X are the connections from the switches 4-4 shows this variation. In the illustration a screw that change the polarity of the frogs. If the turnouts terminal strip is shown fitted to both the baseboard have built-in live frog switches a local dropper will and the control panel with the necessary connecting need to be provided. If not, a connection to the tie- wires. If the layout is intended to be portable a bet- bar operated microswitch termination can be used. ter method would be to use multi-pin plugs and Although this method requires additional wires to sockets to make the process of connecting and dis- be brought from the layout to the isolating switches, connecting easier. Some examples of plugs and sock- it is preferred as it ensures that a locomotive cannot ets are shown in Photo 4.2. be moved unless the turnout is correctly set. In All these connections should be listed on a Figure 4-3, isolating rails IR1, IR2 and IR3 are fed wiring schedule and kept with a copy of the layout in this way. schematic. Preparing a schedule is an important

a) Pt 1a Pt 2a F2 F1

CR CR F3 IR2 IR1 IR3 Pt 1b Pt 2b

P1bx P2bx CR

Common Return Power Feed Edge of Baseboard

a) Sketch showing connections Output from Controller between droppers, isolating switches and input from the controller. The additional isolation F2 F1 rail breaks required are shown IR3 P1bx F3 P2bx IR2 IR1 circled. It is assumed that the isolating switches are mounted on CR CR the baseboard close to the edge and CR roughly opposite the sections of track that they control. The live frog Connection to droppers associated with turnouts Baseboard 1b and 2b are identified as P1bx and P2bx. Control Unit b) b) The same circuit shown as a simple wiring schematic. FIGURE 4-3

An alternative option to mounting the switches step, particularly for newcomers to wiring, as it can on the baseboard would be to have a separate con- save considerable time in tracing faults should they trol panel, particularly if it is intended to have elec- develop at a later stage. A simple schedule associat- trically operated turnouts and signals at a later ed with Figure 4-4b would appear as follows: stage. In this instance the four Isolating Rail switches would be mounted on the panel and their

8 - 4 - 4 Part 8 Section 4 LAYOUT WIRING Issue Date November 1997

Terminal No Baseboard Control Panel Feed from/to 1 Engine spur F2 Switch (4) Power feed 2 Isolating Rail 3 Switch (3) Turnout 1BX 3 Turnout 1BX Switch (3) IR 3 4 Common Rails Power return Control Unit 5 Feed rails F1, F3 Power feed Control Unit 6 Turnout 2BX Switch (2) IR2 7 Isolating Rail 2 Switch (2) Turnout 2BX 8 Isolating Rail 1 Switch (1) Turnout 2BX via Switch (2)

PHOTO 4.2 A length of terminal strip or ‘chocolate block’ screw connector suitable for permanent wiring. This can be cut to length with a craft knife. The 8 and 12 way plug and socket connectors can be permanently mounted or, when provided with a protective cap incorporating a cable clamp, used as jumpers between baseboards.

4.3 Goods Sidings. branch line terminus of the type that could be found in many parts of the country up to the mid-late 60s. A fan of dead end goods sidings would normally The four rail breaks shown divide the layout into require a single feed and return connection at the four areas and are to ensure that there is no chance toe of the fan. Unless additional stabling points are of cross feeds and possible short circuits when the needed, individual sidings would be isolated by set- turnouts are operated. The four feed and return ting the turnout against them. This is described and wiring connections to these areas follow the illustra- illustrated in Section 3, sub-section 3.1 and Figure tion methods used in most of the model press, i.e. 3-7. they are connected at the toes of their respective groups of turnouts. If only one engine is present on the layout at any one time, they could be joined 4.4 A Typical Branch Line Terminus together and taken directly to the controller output. The wiring schematic is similar to that shown in Figure 4-5 combines the elements described in the Figure 4-2 with the addition of the two connections two preceding sub-sections and represents a typical for feed and return to the goods sidings.

8 - 4 - 5 a) IR3 CR P2bx IR1 FIGURE 4-4 F2 P1bx F1/3 IR2 a) Additional connections required for a separate control panel. Baseboard 12345678 b) The wiring schematic. Compare this with the schematic in Figure 4-3.

Engine Release ESR2 ESR1 Spur Road Spur

Common Feed Control Panel

Input from Control Unit

F2 F1 b) F3 IR3 P1bx P2bx IR2 IR1 CR CR CR

23 1 45 678Connection to Baseboard (3) (4) (2) (1)

Control Unit

a) Feed Power supply Return to Rail Electrical Break Goods Sidings in both rails

Parcels F4 Headshunt CR Platform F2 F1 CR Platform Road CR Main Line F4 F3 Release Road Spur Release Road CR Engine Service Road F2 F1 F3

Carriage Siding CR

CR CR CR

a) Typical single line branch terminus showing power Connection to Baseboard feed and return connections to the four control areas. b) Simple wiring schematic based on one engine in b) Control operation. Unit FIGURE 4-5

8 - 4 - 6 Part 8 Section 4 LAYOUT WIRING Issue Date November 1997

4.5 Two Trains at once troller. These should be two-way centre-off types to provide isolation as well as controller selection. Referring to the track plan of the terminus, it will Figure 4-6a shows the track layout with the addi- be seen that it is possible to have three trains mov- tional breaks to provide stabling turnouts for loco- ing at the same time, although two would be a more motives and Figure 4-6b shows the wiring schemat- realistic maximum. One train could be moving on ic. A simple control panel with the switches mount- the main line while a second could be shunting in ed in a line appears in Figure 4-7. To move a train the sidings. The introduction of a second controller from one area to another requires the appropriate would require four additional switches to be fitted area switches to be selected to the same controller. to supply the four feed rail areas from either con-

Electrical Break in Feed rail Dropper number P2bx of Point Frog

F2 F1 CR CR

IR3 P1bx F3 P2bx IR2 IR1 CR

a) Track diagram showing additional insulation breaks to provide stabling points for locomotives. The lighter feed arrows F4 show the feeds to these separately CR switched sections. F2 F1 CR CR IR3 P1bx F3 P2bx IR2 IR1 CR

123 4 5 6 7 8910Connection to Baseboard

Connection to Panel Control Control Unit 1 Unit 2 b) Wiring schematic with provision for two locomotives to operate at the same time. The two control units are wired for common return and each track feed is supplied via a two-way centre-off switch. FIGURE 4-6

8 - 4 - 7 Baseboard

P1bx F3 F1 P2bx IR1

IR3 F2 F4 CR IR2

12345678910

Release Engine Release Goods Main ESR2 ESR1 Road Spur Road Yard Line Spur

Common Control Panel

Control Unit 1 Control Unit 2

FIGURE 4-7 A simple control panel for two train operation of the branch terminus based on the schematic in Figure 4-6b.

4.6 Route Selection shown in Figure 4-8. Three new power supply feeds (F1, F2 and F3) are added and three of the original The wiring described above follows the standard feed connections now become Switched Feeds (SF1, convention where, when two controllers are in ser- SF2 and SF3) and are supplied via the additional vice, power is fed to the toes of the turnouts and the switches attached to the adjacent turnouts. layout is divided into a number of areas. An alter- Figure 4-9 is an expanded version of Figure 4-8 native method is to employ a system known as showing both rails, the insulating rail breaks and route selection where the wiring is adapted to suit the additional switches required for power routing. the train movements. The advantage is that the As an illustration of the principle, consider the trac- control panel becomes easier to use and there is less tion power supply to the goods yard. With crossover likelihood of operating errors, particularly when the 3 normal, the power to the sidings is fed from the layout is being operated by visitors who are unfa- headshunt feed F2 via the additional micro-switch miliar with the control system. attached to turnout 3b. While the operator is busy The track layout in Figure 4-5 also appeared in shunting the yard, a second operator can be dealing Part 6, Section 2 and was used to illustrate the fact with movements on the main line into or out of the that location and type of signalling were determined platform or engine release roads. Once shunting is by the track layout and train movements. These completed and the goods train is ready to depart, were; arrival and departure along the main line, reversing crossover 3 operates the additional micro- shunting in the yard from the headshunt and move- switch attached to turnout 3b and transfers the ments into and out of the engine service road. These power supply for the sidings to the main line feed movements can also be used as the basis of a route F1. At the same time turnout 3a isolates the plat- control system. form road preventing unwanted movement towards If the traction power supplies are fed to these the main line. The goods train can then depart three primary locations (main line, headshunt and using the controller selected to the main line. engine service road) and routed to other parts of the Similar switches attached to crossovers 1 and 2 layout by adding switches to certain turnouts, the (P1a and P2b) are also used for power routing and, need to ensure that the area feed switches are all as an example, can make passenger operation easi- correctly aligned is eliminated. This routing is er as the following series of movements show. achieved by converting three turnouts to the heel fed version by adding an extra micro-switch to 1. A passenger train arrives in the platform from them. (Refer to Section 3, Point Wiring, sub-section the mainline having traversed crossovers 3 and 3.3.4 for details of heel fed turnouts). The changes 2 set normal. Traction power for the movement to the droppers and insulation rail breaks are is supplied to feed F1 from, say, control unit 1.

8 - 4 - 8 Part 8 Section 4 LAYOUT WIRING Issue Date November 1997

a) The additional rail breaks required for route selection are shown circled. A new feed and return are required for the headshunt and a feed for the engine service road.

SF1 P3b F2 CR CR

SF2 P1a P2a P3a F1 CR CR

IR3 P1bx P1b SF3 P2bx F3 IR2 IR1 CR P2b

IR3 P1bx SF2 P1af F1 F2 F3 IR2 IR1

CR CR CR CR CR

123 4 5 6 7 8 910Connection to Baseboard

Common Connection to Panel Control Control Unit 1 Unit 2 b) The wiring schematic for the layout. FIGURE 4-8

2. The locomotive is detached and moves forward 4. Crossover 1 is reversed. The micro-switch to the engine spur, over crossover 1 normal, as a attached to turnout 1a transfers the power feed- preliminary to running round the train. This ing the engine spur (SF2) from the platform requires the engine spur isolating switch to SF2 road to the release road (SF3) which is now fed to be ON. from FI. With turnout 4 set normal, the locomo- 3. Crossover 2 is reversed. The micro-switch tive can be driven from the engine spur to the attached to turnout 2b transfers the power feed- main line via the release road still using control ing the release road (SF3) from the engine ser- unit 1. vice road (F3) to the main line (F1) via the sup- 5. Crossovers 1 and 2 returned to normal. The loco- ply to the live frog (3ax) of turnout 3a. The plat- motive is eased down into the platform road to form road is isolated as the live frog (2ax) of recouple ready for departure. turnout 2a is switched from common return Apart from checking that the engine spur isolat- (CR) to connection 3ax, placing both platform ing switch to SF2 is in the ON position, no electrical rails at the same polarity. switching is required to carry out the operation as

8 - 4 - 9 power is routed as required by the movement of the crossovers. A simple control panel for two train operation is shown in Figure 4-10.

SF1 Yard

CR (8) F2 (6)

P3b P1af (4) SF2 (3) CR (8) F1 (5) P2a

P1a P3a CR (8) IR3 (1) SF3 F3 (7) IR2 (9) IR1 (10) CR (8) P4 P2b P1bx (2) P1b CR (8)

FIGURE 4-9 Figure 4-8a expanded to show the individual rails and insulation breaks required for route selection wiring. The individual switches mounted on each turnout for changing the frog polarity have been omitted to avoid cluttering the diagram. The three switches shown operated by turnouts P1a, P2b and P3b are used to route power to the Switched Feeds SF1, SF2 and SF3. Note that because the engine spur at the end of the platform road (SF2) is used a stabling point, its connection from P1a switch (P1af) is taken via an isolating switch on the control panel. The numbers in brackets adjacent to the connections correspond to the baseboard - control panel connections shown on the schematic, Figure 4-8b.

Baseboard

P1bx P1a F2 CR IR1

IR3 SF2 F1 F3 IR2

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Release Engine Main Goods Engine ESR2 ESR1 Road Spur Line Yard Service Spur

Common Control Panel

Control Unit 1 Control Unit 2

FIGURE 4-10 A simple control panel for two train operation using route selection control. Compare with the wiring schematic in Figure 4-8b.

8 - 4 - 10 Part 8 Section 4 LAYOUT WIRING Issue Date November 1997

To Yard a)

IR4 Feed

Main Line IR3 IR2 IR1

a) Track diagram for a three-rail version IR4 IR3 Feed CR IR2 IR1 of the terminus supplied by a single controller. All running rails are Connection to 123456 bonded electrically to form the common Baseboard return. All third rails are bonded as traction feeds but with four independently fed sections (IR1 to IR4) to provide locomotive stabling points. Connection to Panel b) The wiring schematic corresponding to the above track diagram. Control Unit b)

FIGURE 4-11

4.7 Three Rail Wiring tems described earlier, the route selection system is the one most suited to three-rail. Referring to (This includes centre third, outside third and stud Section 3, Point Wiring, Figure 3-4 shows a self iso- contact). If the same typical single line terminus lating version of a three rail turnout using a micro- track layout is wired for third rail operation there is switch. If this configuration is used for turnout 4 some simplification as the running rails form the and the three crossovers 1a-b, 2a-b and 3a-b, then, common return for traction power and no switches combined with power feeds to the main line, head- are required to change the frog polarity. Similarly, if shunt and engine service road, control of movement only one controller is in use the third rails can be is by turnout operation. Figure 4-12a shows the con- bonded together to form the power feed. The only nections to the third rail and Figure 4-12b shows isolating breaks are those where a locomotive is the wiring schematic for a layout having a separate required to be held and these are easily produced in control panel. Note that, apart from the dropper the third rail. Figure 4-11 shows the connections identifying numbers which change slightly, the where the isolating switches are located on a sepa- schematic is identical to that used for the two rail rate control panel. version in Figure 4-8b. Similarly, a simple control If a second controller is introduced, the third rail panel would be identical to the panel illustrated in has to be split up into sections each with its own Figure 4-10. two-way centre-off switch. Of the two wiring sys-

8 - 4 - 11 To Yard

P3b F2 Headshunt IR4 P1af P1a P2a P3a F1 Main Line IR3 P1bf P1b P2b F3 IR2 IR1 Engine Service P4

a) Connections to the third rail required for route selection wiring. The microswitches are operated by the adjacent turnouts. Running rails have been omitted for clarity but are bonded throughout and connected to the common return (CR).

IR3 P1bf IR4 P1af F1 F2 F3 CR IR2 IR1

123 4 5 6 7 8 910Connection to Baseboard

Connection to Panel Control Control Unit 1 Unit 2

b) The wiring schematic for the above layout when supplied by two control units. Note that isolating rails IR3 and IR4 are fed from the adjacent third rails (P1bF and P1af respectively). Compare this diagram with Figure 4-8b which is almost identical.

FIGURE 4-12

8 - 4 - 12