POST OFFICE ENGINEERING DEPARTMENT
Issue 2, 1934
POLICE TELEPHONE AND SIGNAL SYSTEM
This Instruction details the apparatus items, under their Rate Book descriptions together
with general information regarding their provision.
HEADQUARTERS EQUIPMENT (EXCEPT POWER PLANT)
2. Switchboards P.A.101
Suitable accommodation will be provided by the Police Authorities, and the following
switchboard dimensions are given to assist in the selection.
|(a) Height of switchboard
|(b) Width of switchboard
|(c) Depth of switchboard (maximum)
|(d) Depth of switchboard (minimum)
3. The reduction of width from (c) viz. 3 ft. to (d) viz. 2 ft. is
possible by dropping the keyshelf, which is hinged for this purpose.
4. Clocks No. 37
A mechanical 8-day clock, with 6-inch dial flush-mounted, is provided on the front of each
5. The grouping of switchboard units, in the panels of the switchboard, will be
arranged to meet local requirements.
6. The relay controlling the trickle-charging of the filament batteries will be fitted
in a suitable position inside the switchboard.
7. Unit, Switchboard P.A. No. 1
This is a jack-in line unit for the party-lines, and will be requisitioned on
the basis of one per party-line group fitted, plus one spare unit per switchboard - to be
held in a position provided inside the switchboard.
8. Handles, Key, No. 1, Yellow will be requisitioned
and fitted, in place of the black key handles supplied with the unit, on each key
associated with a call point equipped with a signal lamp, in schemes where signal lamps
are not fitted at every call point.
9. The labels on the units will be forwarded together with
engraving schedules, in accordance with the normal procedure, to be engraved with the code
for each call point as agreed upon locally.
10. Additional Units will be requisitioned and fitted as, and when, additional groups of
street call points are required.
11. Units, Switchboard P.A. No. 1 dummy
These are dummy panels required to fill up the unequipped positions in the switchboard
panels containing the party-line units. The number requisitioned for each switchboard will
be the difference between the number of party-line groups fitted and the capacity of the
12. Vibrator, Ringing No. 4A
These are supplied in accordance with the capacity of the switchboard, and are provided
with the switchboard. They jack-in on a metal frame for wall mounting.
13. As the noise during operation is likely to be disturbing to the operator, the
vibrator should be fitted in a position outside the switchroom.
14. Dynamotor No. 20 is a D.C. to D.C. converter, for
providing the high-tension supply to the amplifying valves. Input 22 volts; output 180
volts, 60 milliamps. One Dynamotor No. 20 is provided as part of each
15. Unit, Amplifying, No. 10 is a two-valve amplifier, two of which are
supplied as part of each switchboard equipment, to provide amplified speech currents for
the loudspeakers at the street call points.
16. Valves, Thermionic, No. 76 and No. 77
One of each is supplied with each Unit Amplifying No. 10. No. 76 is a Mullard
P.M.6D., and No. 77 is an Osram P.625A.
17. Extension of Public Call Alarm
The relay, with the mercury tube contact, required for this circuit is contained in a wood
case, and is supplied with the switchboard. Where this circuit is required, the relay will
be fitted in any desired position within the curtilage of the Police station, and the
signal light - consisting of a red-coloured 25-watt electric lamp, obtained locally - will
be fitted alongside, in series with the mercury tube contact and electric light mains. The
connexion to the electric light mains for this lamp will be provided by the Post Office
with the agreement of the Renter, who will supply the current.
CALL POINT EQUIPMENT
18. Unit, Telephone P.A. No. 1 is a telephone unit required for a
street call point fitted as a terminal station, and includes Hook,
Receiver U, and Telephone No. 164 with cord instrument No. 380. One unit
will be requisitioned for each party-line group.
19. Internal signal lamp
When the Unit, Telephone P.A. No. 1 is fitted in a kiosk, one Lamp,
General Purpose 25-watt will be requisitioned separately for each unit, for the
signal light associated with the unit.
20. Unit, Telephone P.A. No. 2 is the telephone unit required for a street call point
fitted as a side station, i.e., an A, or B call point, and
includes Hook, Receiver U and Telephone No. 164 with cord instrument
21. Internal Signal Lamp
When Unit, Telephone P.A. No. 2 is fitted in a kiosk, one Lamp, General
Purpose 25-watt will be requisitioned separately for each unit, for the signal light
associated with the unit.
22. Hook, Receiver U, also Telephone No. 164 with cord
instrument No. 380 for use with Unit, Telephone P.A. No. 1 or No. 2,
can be obtained separately upon requisition, if required.
23. Cord instrument No. 380 is 18 inches in length. This is of the cab
tyre flex type, and forms part of Telephone No. 164 with cord instrument No.
380. This can be obtained separately upon requisition, if required.
24. Cord instrument No. 381 is similar to Cord, instrument No.
380. This can be obtained in continuous length, upon requisition, when a long cord
25. Bracket P.A. No. 1 is a bracket to support the mounting for
Units, Telephone P.A. Nos. 1 or 2 in cases where line units are fitted in a
kiosk. It includes the public call door and grille structure, complete. This is supplied
as part of the street pillar, but must be requisitioned separately when the telephone unit
is fitted in a kiosk.
26. Mounting for Unit, Telephone P.A. No. 1, is the mounting base on which
the telephone units are fitted in both kiosks and pillars.
27. Level of mounting
It is essential for the satisfactory working of the mercury contacts in the telephone unit
that the mounting be level, and provision is made for slight adjustment of the level by
means of washers.
28. Earthing of Unit and Structure
Since power from the mains is carried into the telephone unit for the working of the
signal light, it is necessary that the cover of the telephone unit should be earthed. The
tubing carrying the power cables from the Power Companys cut-outs to the telephone
unit will be earthed in accordance with normal practice, and this tubing will be
effectively screwed to the mounting base, at the point where the power cables enter, by
means of lock nuts.
29. Posts, P.A. No. 1
This is a cast-iron street pillar to accommodate “Units, Telephone P.A. Nos. 1
or 2,” together with “Lantern P.A. No. 1“ where required (for lamp see picture
at bottom of page).
30. This item includes the public call door and grille structure complete, also
Mounting for Unit, Telephone P.A. No. 1, and a Lantern P.A. No. 1
31. A First Aid Compartment is provided in the body of the pillar for the
accommodation of a first aid outfit, which, if required, will be provided and maintained
by the Police Authority.
32. One Key, Lock N is provided with each pillar for the lock on the door
of the police compartment. Where a number of keys is required by the Police Authority,
arrangements should be made to supply these under direct sale terms. The direct cost of
Keys, Lock N is 10d. each, and the sale should be negotiated in accordance
with Engineering Regulation F. 1/85.
The pillar will be erected, if possible, in the footway alongside the kerb, and will be so
placed that the police side, and public side, and also the first aid compartment, will be
towards the footway.
34. The base of the pillar will be sunk in the ground, and suitably set in concrete.
35. Earth plates
An efficient earth is essential at each street call point, and arrangements will be made
to sink an earth plate during the erection of all pillars and kiosks.
36. Lead-in pipes
Two pipes G.I. 3/8 inch will be laid through the concrete into the base of the pillar
during erection, for the lead-in of the telephone and power cables.
37. Lead-in cable
All cables to pillars will be led-in direct from underground, and, where it is not
possible or economical to connect with underground mains direct, the overhead line will be
terminated on a pole, or building, suitably situated, and led in by means of underground
cable from that point.
38. The call point numbers will be painted on the grille structure of the public call
door, at the left of the grille; and, if desired, on the inside of the police compartment
door. If the call point numbers are engraved on the labels on the switchboard units, the
quick identification of a call point from which a call is being received will be
39. Label No. 206 is a not in use label, which is fitted to
the public call door of street call points during installation, and is recovered when the
system is brought into use. This is fixed from the inside by means of a bolt, which passes
through the grille structure and prevents the public call door from being opened.
40. Label No. 201 is a public instruction label, to be affixed to the
outside of the public call door on both pillars and kiosks. It is enamelled iron, with
white lettering on a red ground, and reads:
To call, Pull and Hold Door Open
For Public Use
41. If a Police Authority desires any alteration in the above, the matter should
be referred to the Engineer-in-Chief (Telephone Section) with full details.
Red is the standard colour of paint to be used for all pillars. After
erection, the pillars, which will be issued with a primer coat, will be given one coat of
Paint, Kiosk, Undercoat, and one coat of Paint, Kiosk, Finishing,
Special Red, to be obtained upon requisition from the Stores Department.
These will be provided by the Renter in all cases (see P.3002) but particulars of the
dimensions of, and method of fixing, the public door and grille structure will be supplied
to the Renter, so that suitable fixing facilities may be provided for these items. These
details will be obtained from diagram P.A.125.
Tool, Instrument No. 243 is supplied upon requisition from the Stores
Department for operating the triangular-headed screws on Posts, P.A. No. 1
and Lanterns P.A. No. 1.
45. Tool instrument No. 245 is a two-pin driver for locking the
fixing bolts of Label No. 201.
46. Lantern P.A. No. 1 is a cast-iron lantern which may be fitted on
Post, P.A. No. 1, or in other positions as required, to provide a visual
signal for calling the attention of Police Officers.
47. Special bracket for kiosks
The lantern is provided with a flat base; when it is required to be fitted on a kiosk, it
will be necessary for the Renter to provide, on the kiosk, a suitable bracket to which the
lantern may be fitted. Fixing is effected by means of three bolts and nuts, supplied with
the lantern, and the Sectional Engineer will provide the Renter with a copy of diagram
P.A. 126 - which is a dimensioned sketch of the drilling required for the fixing of the
lantern - so that the bracket may be drilled to suit.
48. Wall brackets
When it is required to fit the lantern on a wall bracket, the bracket and cabling between
the telephone unit and the lantern will be supplied, fitted, and maintained by the Renter. The lantern, and electric bulb, will be supplied and maintained by the Department, except
in any special case where the position of the lantern on a bracket will present
exceptional maintenance difficulty, when the lantern and electric bulb will also be
supplied and maintained by by the Renter.
49. Glass No. 40“
This is a specially-constructed cylindrical lens, and one is supplied with each lantern. The lens is specially treated to give an amber-coloured light, which is the standard
colour for the signal light.
50. Electric bulb
A 100-watt drawn-wire filament electric lamp will be used for the signal light in the
lantern, and will be obtained by local purchase.
51. Lantern, P.A. No. 1 dummy will be recovered in all cases when a
lantern is provided on a pillar.
52. Bell No. 60A Unmounted
The dome of the Lantern P.A. No. 1 is made of bell metal, and a Bell No.
60A Unmounted may be fitted inside this when an intermittent audible signal is
required in conjunction with the flashing signal light. The bell is a solenoid gong
movement, and is arranged to provide for working on 100 - 130 volt D.C.; 200 - 260 volt
D.C.; or 200 - 260 volt AC. This item will be requisitioned separately when required.
53. Power Supply for lamp
This will be provided, together with the necessary cut-outs, by the Renter, see P.3002.
54. External wiring of Call Points
In order that the full line-testing facility may be obtained throughout the line, the
routing of the line must be from the Switchboard, direct to the A call point;
thence direct to the B call point; thence to the terminal call point; i.e.,
the external line must be led in and out at the A and B call
points. It must also be borne in mind that the total line resistance must not exceed 500
55. Accommodation for the necessary power plant will be provided by the Renter,
This will be carried out in accordance with the instructions contained in Technical
Instructions XXIV, part 1.
57. Main Battery
Cells, Secondary, Stationary No. 6 will be installed for the four main
batteries, where a 30-line switchboard is provided, and Cells, Secondary, Stationary
No. 5 will be installed where 10-line or 20-line switchboards are provided.
58. Amplifier Filament Battery
Cells, Secondary, Stationary No. 1 will be provided in all cases.
59. Charging Panel
A Panel, Charging No. 28 will be required. This will be issued without the
Ampere hour Meter, which will be requisitioned separately.
60. A Meter, Ampere hour No. 1/50A will be required in cases where
Cells, Secondary, Stationary No. 5 are installed; in other cases, a
Meter, Ampere hour No. 1/100A will be necessary.
61. Charging Plant
This will be in accordance with T.I. XXIV, Part 1, having regard to the power supply
available, and the local requirements.
62. Separation of telephone and power Cables
In this system amplified speech currents are employed on certain connexions, and the
possibility of interference from induction in the circuits is therefore increased. In this
connexion special attention is drawn to the instruction in T.I. XXIV, Part 1, paragraph
100, with special reference to the cabling between the charging panel and the batteries.
63. Power Supply
The power supply and the power cut-outs will be provided by the Renter, see P.3002.
|Lantern P.A. No. 1