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The Protofour Manual
Unit Wiring System


Electrical instructions and diagrams seem complicated when seen for the first time. However, they are basically simple and are easy to understand if each stage is studied in the correct sequence.

Protofour Unit Wiring has been designed to enable a modeller with no knowledge of electrical principles and no experience of wiring to plan and install a reliable model railway wiring scheme.

It is most desirable that the wiring and control diagram of a model railway layout should be drawn in conjunction with the track plan. This enables the necessary connections to be provided for in the jig construction stage. If this is not done, wiring becomes a haphazard, difficult and frustrating operation which makes excessive demands upon-modelling time and patience, with a high risk of failures and damage to the appearance of the finished layout.

Protofour Unit Wiring is a standard form of electrical wiring for model railway layouts and is based on the use of Protofour Wiring Connector Strip (WCS) and Turnout Bonding Strip (TBS). The 'external' wiring connections to the track are effected through WCS, one end of which is clamped to the sleeper base by the base of the track rivet, and thus feeds the rail through the rivet head; the other end is fitted with a dropper wire leading to a terminal block below the baseboard. The 'internal' bonding of rails, for example wing and vee rails at crossings, is carried out using Turnout Bonding Strip laid along the base of the timber and held by the rivet base. Both forms of connection are invisible when track is finally laid.

Protofour Unit Wiring has five component parts:

  1. Principles of Layout Wiring.
  2. Wiring Diagrams.
  3. Wiring Index.
  4. Wiring Templates.
  5. Control Diagrams.

The Principles of Layout Wiring are a summary of the basic rules for wiring a model railway.

The Wiring Diagrams are simplified, schematic wiring plans for the types of track unit found in the range of Construction Templates. Wiring Diagrams are also provided for certain combinations of standard units commonly found in the prototype.

The Wiring Index is the means by which the electrical connections shown schematically in the Wiring Diagrams maybe translated into actual locations on the construction templates. Each WCS, TBS and Essential Rail Break (ERB) is indicated in terms of the crossing timber identification number on the appropriate construction template. Using the Wiring Index for the construction template concerned, the WCS, TBS and ERB positions can be marked on the template before construction commences. The necessary connections may then be provided during construction of the track unit in the jig.

The Wiring Templates are the electrical equivalent of the track planning templates, and may be used to build up an electrical equivalent of the layout in exactly the same way as the planning templates build up a diagram of the track. They are similarly printed on self-adhesive paper.

The Control Diagrams indicate the several forms of control which may be used in conjunction with Protofour Unit Wiring. ANY desired control system may be incorporated into the wiring plan produced from the wiring templates, and one form of control may be exchanged for another at any time.

1. Principles of Layout Wiring


2. Wiring Diagrams

Protofour Wiring Diagrams are based on the rail patterns shown in the construction templates. Although they are not to scale, they show clearly the correct form of bonding by means of TBS, the feeds through WCS, the Polarity Switch connections, and the Essential Rail Breaks (ERB). Additionally they show the 'external' connections to adjoining sections of track. This information is given for all track formations found in the track construction template range, and also for certain combinations of these formations commonly found in the prototype.

The following standard symbols are used to indicate the type of electrical connections and the form of switchgear.

Wiring symbols

Running rail terminating at the end of a track unit.


Essential Rail Break (ERB). Irrespective of the control system employed, these breaks MUST be incorporated.


Rail bonding using TBS. This bonding is consistent with the Essential Rail Breaks in dicated in the unit. (If additional rail breaks are incorporated, additional TBS bonding may be required).


Polarity switch. These switches are linked up, and worked by, a turnout operating mechanism and are denoted by the hatched line. They automatically select the correct polarity for the Controlled Feed, and thus for the crossing, in accordance with the setting of the turnout switches.


Turnout operating device


Direct Feed (DE) wiring.

Direct Feed (DE) wiring of opposite polarity to the red DE


Controlled Feed (CF) wiring.


Direct Feed (DF) connection (red or green). Running rails are fed via WCS feeds from dropper wires terminating at tag boards or terminal blocks below the baseboard.


Controlled Feed (CF) connection (blue). All common crossings, and certain types of obtuse crossing, are electrically isolated from the adjoining running rails. They are fed via WCS and Controlled Feeds from polarity switches linked to the turnout operating device.


Adjacent Feed (AF) connection to the next track unit.


Bridged Feed (BE) connection to the next track unit.


Recommended Bus Bar connections.


Wiring junctions.


More than the necessary minimum of WCS and TBS connections are shown in the diagrams. These 'extra' connections should be incorporated to provide a 'fail-safe' operation in the event of one connection becoming defective.

The Unit Wiring ensures that WCS and TBS connections are standard throughout, irrespective of the control system employed. however, with multiple controller operation the CF switch gear is more complicated in certain track formations. Wiring diagrams for these cases are not included in the first part of this leaflet.

Fig 1. Plain track units

Wiring diagram for plain track units
WCS feeds should be installed at the third or fourth sleeper from the rail break.
AF/AF connections only are required.
AF/AF connections may be replaced by isolating switches if track sections are required to be rendered electrically 'dead', for example in locomotive sidings. (See also Fig: 12).

Fig 2. Plain turnout

Wiring diagram for plain turnout

Wiring is identical for curved or 'Y' turnouts.

Figs: 3 Single slip with single controller feeds

Wiring diagram for single slip with single controller feeds

Motive power will only operate through the diamond if the second switch is set for the slip road. If possible, levers should be interlocked to prevent both switches being simultaneously set for the through roads. (See also Figs 4, 13 and 15)

Figs: 4 Double slip with single controller feeds.

Wiring diagram for double slip with single controller feeds

Motive power will only operate through the diamond if the second switch is set for the slip road. If possible, levers should be interlocked to prevent both switches being simultaneously set for the through roads.

Fig: 5. Three throw turnout. (Asymmetrical)

Wiring diagram for three throw turnout (asymmetrical)

Fig: 6. Three throw turnout. (Symmetric)

Wiring diagram for three throw turnout (symmetric)

The switches controlling entry to the left hand road are operated by the unit nearest to the switch toes.

Fig: 7. Tandem turnout. (Unsymmetric)

Wiring diagram for tandem turnout (unsymmetric)

Fig: 8 Diamond crossing with single controller feeds.

Wiring diagram for diamon crossing with single controller feeds

The Controlled Feed polarity must be set by a polarity switch controlled by the turnout switches or a signal giving access to the crossing. (See Figs; 9, 11, 12 & 13).

Fig: 9 Double junction with single controller feeds.

Wiring diagram for double junction with single controller feeds

For completeness, single controller wiring has been included. However, greater flexibility of operation maybe obtained from the use of dual controller wiring. This wiring is detailed in Protofour Manual Section 4.1.9. As in the diamond in Fig: 3., one pair of switches must be set for the slip road to enable motive power to cross the diamond.

Additional coloured wiring diagrams

3. Wiring Index

All Direct Feeds (DF/WCS), Controlled Feeds (CF/WCS), Turnout Bonding (TBS) and Essential Rail Breaks (ERB) shown in the Wiring Diagrams are incorporated into the trackwork during construction in the jig.(Protofour Manual Section 4.1.6.)

The Wiring Index lists the serial numbers of the timbers found on the construction templates against the template designations and the codes for wiring feeds from the Wiring Diagrams. Using the Index, it is a simple matter to transfer the appropriate feeds to the construction templates and to incorporate these during construction of the unit.

If substantial numbers of units are to be built, it is recommended that a set of the desired templates be marked and used as master references.

4. Wiring Templates

This aspect of the Protofour Unit Wiring System is described in detail in Section 4.1.9. of the Protofour Manual.

5. Electrical Control Systems

This aspect of the Protofour Unit Wiring System is described in detail in Section 4.1.9. of the Protofour Manual.

Wiring Installation - Single Controller operation.

Protofour Unit Wiring enables the installation of any form of control system in conjunction with the wiring. However, for the beginner, the initial wiring of a single controller system enables the wiring to be tested in its simplest form before a more complex system is installed.

The procedure for installing wiring for a single controller operation is as follows:

  1. Select the construction templates for the track units to be built.
  2. Using the Wiring Diagrams and the Wiring Index, mark all WCS, TBS and ERB positions on the templates. If two or more templates are combined to form one unit, carefully check the positions of the rail breaks. (See note below).
  3. Construct the track as described in Protofour Manual Sections 4.1.3. and 4.1.6., incorporating all feeds and breaks previously marked.
  4. Lay the track, and solder dropper wires to all WCS feeds.
  5. Mount terminal blocks or tag strips below the baseboard and connect each dropper wire to its terminal.
  6. Using the Wiring Diagrams, connect together the terminals representing AF/AF connections. Where appropriate, connect together the AF/BF terminals. (See Diagrams 1,11, & 12).
  7. Check that there are rail breaks corresponding to each AF/BF connections.
  8. Connect the CF terminals with the appropriate polarity switch outlet and the appropriate DF connections to the polarity switch inputs as shown in the Wiring Diagrams.
  9. Check the wiring and track to ensure that all connections have been made and all loose debris removed, (to avoid possible short circuits).
  10. Join the output terminals of the power pack/controller to any pair of red/green terminals. With Protofour Unit Wiring it should be possible to operate a locomotive over any part of the layout.


Protofour Turnout Bonding Strip and Wiring Connector Strip.


The purpose of Turnout Bonding Strip (TBS) and Wiring Connector Strip (WCS) is to provide respectively the electrical bonding of adjacent rails in certain track formations, and power feeds to the running rails, in accordance with the Protofour Unit Wiring system.

The use of these strips virtually eliminates the problems of layout wiring, as the TBS is integral with the track, thus dispensing with the use of wiring for 'internal' bonding, and the WCS provides wiring terminals for the connection of 'external' power feeds. Protofour soldered rivet track construction allows these connections to be incorporated in the track during construction in the jig, so that the electrical and mechanical aspects of the track are covered in the same operation. This represents a very considerable saving in modelling time, and also ensures that all connections are invisible once track is laid.

Bonding strip 1. Turnout Bonding Strip (TBS).

2. TBS fitted to underside of Crossing Timbers and rivetted.

3. Wiring Connector Strip (WCS).

4. WCS rivetted to underside of Crossing Timber for Track Feed.

Turnout Bonding Strip (TBS)

This is a 1/8" wide self-adhesive copper foil strip which is applied to the base of the sleeper or crossing timber. Rivets set through and over the foil are electrically bonded by the strip, as are the rails to which the rivets are soldered. To ensure a permanent bond the foil and rivet bases may be given a coating of resin-cored solder, residual flux being removed with methylated spirit or a glass -fibre brush.

Where aluminium TBS is supplied instead of copper the procedure is the same, but the operation of coating with resin-cored solder is omitted.

This method of rail bonding is simple, neat, rapid and invisible once track is laid.


  1. Use scissors to cut the desired length of TBS.
  2. Select the timbers to be bonded AFTER punching but BEFORE riveting.
  3. Remove the protective backing from the TBS.
  4. Apply the TBS to the timber base to cover the rivet holes of the bonding group.
  5. Re-run the timber through the punch tool with the foil to the base of the tool for clean punching, and re-punch the existing holes.
  6. Insert rivets in the usual manner remembering that the foil will form the base of the timber.
  7. Rivet the timber so that the rivet bases spread over and hold the foil.
  8. Solder rivets and strip using a resin-cored solder.
  9. Clean the joints using methylated spirit or a glass-fibre brush to remove all traces of flux.
  10. Cut insulation gaps if necessary by slitting; the foil and peeling away the unwanted strip

Wiring Connector Strip (WCS)

This is a 1/8" wide hard brass strip perforated at intervals to receive rivet shanks. Its greater strength enables it to be used as a free standing power feed to the rails where TBS would prove too fragile. One end of the WCS is held below the base of the track rivet and the other in a slot in the underlay where it is connected to a vertical dropper wire leading below the baseboard.


  1. Insert rivets into the timbers as in normal track.
  2. With the timber in the slideway of the riveting tool, hook the end WCS hole over the appropriate rivet shank, and operate the press so that the rivet base turns over and holds the WCS.
  3. Leaving a tab as shown in the photograph, cut away the excess WCS using metal cutters.
  4. Solder the WCS to the rivet base using resin-cored solder.
  5. Clean the joint usIng a glass- fibre brush.

Maintenance of track levels in the jig.

The addition of WCS to the base of the sleeper or crossing timber increases the thickness. To counteract this, and preserve the rivet heads at a uniform level in the jig for soldering, the following procedures are recommended.

  1. In a simple unit, the timbers carrying the WCS feeds can be omitted from the jig and soldered in place when the formation has been lifted from the jig.
  2. Alternatively, in a complex unit a base of thin card can be placed using double-sided adhesive tape between the template and the jig surface. After the positions of the WCS feeds have been marked, slots can be cut through the template and card, and the area so removed will allow the WCS feed to be recessed thus preserving rail levels. Modellers may well prefer to adopt this latter system for all formation

On the layout itself, the underlay will have been removed below the WCS feeds to facilitate the fitting of dropper wires.

Electrical track feeds. (Direct and Controlled Feeds)

Power feeds to the track are always provided through WCS connections, by means of wires leading from the free end of the WCS directlybelo\v the baseboard. This method allows for invisible connections below the ballast, and ensures that in the event of an accidental pull on the feed wire, the track and its electrical continuity remain undisturbed.


  1. Place the track unit on the underlay and carefully position it in the exact location that it will be laid.
  2. Carefully mark the cork underlay where the WCS feeds occur.
  3. Cut slots in the underlay to accept the WCS feeds.
  4. Install the track section.
  5. Drill a small vertical hole in the base of the underlay slot, adjacent to the end of the WCS, to penetrate the underside of the baseboard.
  6. Prepare feed wires (dropper wires) each with a small hook at the end.
  7. Drop the wires through the vertical holes and solder the hook end to the WCS using resin-cored solder.
  8. Fill and ballast the underlay slot.


Notes for use with index tables.