P.A. 450 POLICE SYSTEM

POLICE TELEPHONE AND SIGNAL
SYSTEM P.A. 450
Installation of Call-points

1. Scope of Instruction
This Instruction describes the erection and installation of the equipment required at the street call-points for the Police Telephone and Signal System P.A. 450.  Its contents are arranged as follows:-

2. General
The call-point equipment Consists of a telephone and signalling unit, together with associated signal lamp, housed in either a metal street post or in a kiosk of suitable design and situated in a prominent position in a public thoroughfare.  The street post currently used for new work is the Post, P.A. No. 3.  This supersedes the Post, P.A. No. 2 which is similar in appearance but made use of a different method of construction.  The telephone is so mounted as to be readily accessible for use by either police or public.  A general description of the equipment is given in P 1301.

3. The police authorities will decide whether Posts, P.A. No. 3 or kiosks will be used.

4. Siting of call-points
The choice of sites for the call-points is the responsibility of the police authorities, who will also negotiate all wayleaves necessary for the erection of the call-points.  Assistance should be given to the police authorities in deciding final locations so that, wherever possible, difficult cabling operations may be avoided and to ensure that, when erected, each position gives easy and safe access to the telephone compartment and maximum possible shelter from prevailing wind and rain.

5. Earth connexions
An efficient earth is essential at each street call-point and arrangements should be made to sink an earth plate during the erection of all posts and kiosks. The method adopted should be in accordance with PROTECTION, General, S 3901.  If an earth circuit-breaker is required, it should be fitted in the bottom compartment of the post.

6. Lead-in cables
All cables to the posts should be led-in direct from underground.  Where it is not possible or economical to connect with underground cables direct, the overhead line should be terminated on a suitably located pole or building, and led-in by means of underground cables from that point.

7. Lead-in pipes
Two Bends, Asbestos-cement, No. 3, one for the telephone cable and the other for the power cable, should be set into the base of each post during its erection.  To prevent the entry of gas, the pipes should be sealed in accordance with LINES, Underground, K 3003.

8. Erection of Posts, P.A. No. 3
The Post, P.A. No. 3 should be set on a firm concrete foundation. An excavation should be made of approximate dimensions 2 ft. x 1 ft. 6in. x 1 ft. 6 in. deep.  The actual dimensions of the foundation provided will depend upon the situation and the nature of the ground.  The depth may be decreased to 1 ft. if a larger area can be provided, but each case will have to be decided on the local conditions.  After positioning the lead-in pipes (see par. 7), the excavation should be filled with ‘A’ quality concrete and four Bolts, Foundation, Indented, No. 1 (or equivalent) set in the concrete.
[NOTE: ’A’ quality concrete consists of one part of Portland cement, two parts of sand and four parts aggregate.  The aggregate comprises clean, screened river ballast, gravel stone or other approved material graded in size up to 0.75in.]

A simple wooden or metal template (prepared locally) should be used to ensure the correct setting of the lead-in pipes and foundation bolts.  Care should be taken to ensure a level surface of the finished concrete.  When laid, the foundation should be protected from the action of frost, shielded against too-rapid drying by exposure to the sun or wind, and guarded for at least 48 hours, to ensure that it will be set thoroughly before erection operations are commenced.

9. Before the erection of the post, the surface of the concrete should be thoroughly cleaned and a bedding of cement-mortar laid to a depth of 0.5 in. over that part of the surface on which the base flange will seat.  The post should then be set in position and secured by the foundation bolts.

10. The cement-mortar should then be struck off level with the inside surface of the concrete and, on the outside, the mortar should be trowelled to form a fillet around the post flange, to assist in the drainage of water.  The concrete inside the post should be coated with bituminous compound to form a seal against the ingress of moisture.

11. Fitting of lantern glass
To prevent the entry of rain and dust into the telephone compartment of a Post, P.A. No. 3, it is necessary for the lantern glass (Glass No. 68 - Amber), which is requisitioned separately, to be fitted in position immediately after the erection of the post.  Alternatively, if this is not practicable, the lantern aperture should be plugged with cotton waste or similar material.

12. Painting
The standard colours to be used for the posts are blue outside with the interior white.  The posts are issued with only a priming coat on the outside and, after erection, the exterior should be given two coats of Paint, Glossy Blue.  The interior should not need further painting, but if necessary a further coat of Enamel, White, Finish may be given.  Care should be taken that the painting does not prevent the easy removal of the screws holding the lantern on the top of the post.

13. Equipment of Posts, P.A. No. 3
Each post requires one of each of the following components:-
Telephone No. 244, minus Cord.
Unit, Signalling, P.A. No. 2.
Cord, Instrument, No. 7/10M, 14 in.
Lamp, General Service, ... V/60W Pearl.
Lamp, General Service, ... V/150W Pearl.

The voltage of the lamps should be that of the local supply.  Diagram PA 459 shows the internal connexions of the various items of equipment.  The Telephone No. 244, minus Cord should be secured to the shelf in the top compartment by means of two wood screws and connected to the block terminal on this shelf by means of the Cord, Instrument, No. 7/10M, 14 in.  The Unit, Signalling, P.A. No. 2 should be fixed in position by means of the screws provided; tapped bosses exist in the rear of the centre compartment for this purpose. A length of Cable, P.V.C., No. 1, 4 Wire 64 ..., run via the conduit, should be used for the connexion between the signalling unit and the telephone terminal block.

14. Protection
A Protector and Fuse No. l should be fitted in the base of the post if required under the terms of PROTECTION, General, B 1002.  A length of Cable, P.V.C., No. 1, 3 Wire 64 ... should be run between the terminal block and the protector, via the conduit provided in the right hand rear of the post.  Some posts may be issued with a protector already fitted and if not required it should be recovered and used locally.  If a protector is not required, the lead-in cable should be run direct to the terminal block.

15. The internal wiring for the power supplies is provided with the post.  The police authorities will arrange for the connexion of mains supply to the cut-out. If required, a meter for these supplies may be fixed to the board provided at the rear of the lower compartment.  A Lamp, General Service, V/150W Pearl should be fitted in the signal lantern and a Lamp, General Service, ...V/60W Pearl in the upper compartment of the post.

16. A temporary NOT IN USE label should be attached to the post after erection and prior to the post being brought into service.

17. Locks
One Key, Lock, W is provided with each post.  When a post is brought into service, the key should be handed to the police authorities.  If additional keys are required, arrangements should be made to supply them under “cash sales” terms in accordance with STORES, General, K 0011.

18. Erection of kiosks
The provision and erection of kiosks is the responsibility of the police authorities.  Particulars of the dimensions of the door to the telephone compartment should be given to the police authorities so that a Glass No. 67A may be fitted.  These details should be obtained from Drawing EC 2072.  In addition, the police authorities should be advised that the equipment will benefit in service by the provision of adequate ventilation in the kiosks, thus ensuring a free air-flow and avoiding trouble due to condensation.

19. Special bracket for kiosks
The lantern used for the signal lamp at a kiosk is the Lantern, P.A. No. 1.  This lantern has a flat base and it will be necessary for a suitable bracket to be provided on the kiosk for mounting the lantern.  Fixing is effected by three bolts and nuts supplied with the lantern, and the police authorities should be supplied with a copy of Diagram PA 126 (which is a dimensioned sketch of the drilling required for fixing the lantern) so that the brackets may be drilled correctly.

20. Leading-in arrangements for kiosks should be made during the erection of the kiosks to provide facilities for leading-in the telephone cable.  Where convenient, overhead distribution may be used for kiosks.

21. Equipment of kiosks
A typical layout of the telephone equipment fitted at a kiosk is shown on Diagram EC 2072 and the wiring connexions are given in Diagram PA 484.  A complete list of items to be provided and fitted by the P.O. at each kiosk is given on Diagram EC 2072.  The police authorities will arrange for the power supply to be connected to the cut-out and are also responsible for the provision of any internal lighting that may be required.

22. Audible signals
In addition to the signal lamp, a loud-sounding bell may be fitted at both the post and kiosk.

23. Post, P.A. No. 3
A Bell No. 61A (Bell No. 61B in d.c. areas) should be fitted in the rear of the telephone compartment.  It is necessary to drill and tap blind holes in the post casting to secure the bell.  The Plug, Conduit, No. 2 should be removed from the tee-piece and the conduit extended round to the bell. The bell should be connected in circuit in accordance with Diagram PA 459.

24. Kiosks
If a loud-sounding external bell is required at a kiosk, a Bell No. 61A (Bell No. 6lB in circuit in d.c. areas) should be fitted in a suitable position on the kiosk.  This position should be as high as possible, e.g. immediately under the eaves.  The power cabling should be extended in conduit and the bell joined in accordance with Diagram PA 484.

25. An internal bell may be provided in a kiosk by connecting a Bell No. 64D in series with the line in accordance with Diagram PA 484.

Last revised: March 12, 2023