C MARKETING INSTALLATION
Issue 3, Oct 77
SUBSCRIBER'S PRIVATE METER
Meter No. 19/ ...
The Meter No. l9/..., when connected to a subscriber's line, will indicate to the
subscriber the number of charge units which have been registered on his meter in the
exchange when subscriber trunk dialling is in operation. It will step with the exchange
There are two types of the meter, No. 19/FRA (right) and No. 19/SSS (above and
lower right). They are
interchangeable. In each meter the units' hand and the resettable trip hand move one
division on the scale for each operating pulse. The hundreds' hand moves progressively
over its scale, each division of which represents a complete revolution of the units'
The trip hand can be returned to zero without affecting the operation of the meter by
pressing the reset button or lever.
A total of 9999 units can be recorded and
the trip hand will register up to 99 units.
The meter is operated by pulses of 50 Hz current which are injected into the line at the
exchange. The pulses, nominally at 45 V and with a duration of 200-300 milliseconds, are
impressed on the line longitudinally to earth. The meter is series tuned to 50 Hz and
gives adequate rejection of 17 and 25 Hz ringing frequencies. At PBXS, etc, 50 Hz ringing
should not be used where subscribers' private meters are provided (see Q0005).
The meters are intended for use with DELs (including Extension Plans), cordless
switchboards, PBX extensions, House Exchange Systems, and in exceptional cases one party
of a Shared Service Line.
The first models will be supplied complete with Cord, Inst, No. 3/105L, Grebe, 54 in, for
the Meter No. 19/SSS and Cord, Inst, No. 3/62AB, Grebe, 54 in, for the Meter No. 19/FRA.
The cord connection screws in the meter are located behind the removable panel in the
base. Access into the mechanism is not provided.
1. DELs (Including Extension Plans) The cord will normally be connected to the
instrument terminal block, red and green to line, white to earth. Where the meter is
required remote from the telephone, extension wiring to a separate block, Terminal, No.
52A will be needed.
An earth connection should be provided from the terminal block. Where a protective
earth or a signalling earth exists, this may be used.
Because of the high impedance of the meter, the resistance of the earth connection is
The pulses might be audible on some Extension Plan installations because of unbalance
to earth in the wiring between stations. If this wiring is proved to be at fault, it must
be separated from all other wiring and earth's and run in a non-metallic sheathed cable.
Plans 105 and 107 Meter No. 19 at an Internal Extension Where the meter is required to
function on "Extension to Exchange" calls only, it will be necessary to provide
an Auxiliary Gravity Switch Springset in the extension telephone. This switch (e.g. No. 19
B-1) should be connected between two spare terminals' in order to interrupt the meter
operating earth when the extension telephone hand-set is on the rest.
2. Cordless Switchboards and PMBX Extensions See TI C3 E5001.
3. PABX Extensions and Manual Switchboard of PABX No. 1 See TI C3 F2500.
4. House Exchange Systems See TIs C3 C3034 and C3 C3036.
LOCATION AND FIXING
The location of the meter should be agreed with the subscriber. The subscriber may wish to
have the meter by the side of the telephone for his own use, or remote from the telephone
if the primary purpose is to check the charge incurred by a casual user. The ideal
arrangement for the latter would be to have the meter visible but inaccessible to the
Normally the meter will be free standing, but two blind tapped holes (4BA, 0.44 in
deep) are provided in the base for screw fixing.
||2 Washers No. 4 BA, Small, Oxidised, Lacquered
||3 Washers No. 4 BA, Large, Oxidised, Lacquered
If a wall mounting is required by the subscriber, the meter should be screwed to a
bracket which can be made locally; a suitable design is shown in Drg 91089.
When screw fixing is used, care should be taken that the tapped bushes are pulled
against something solid (such as a distance piece) between the base of the meter and the
baseboard. Never the less the feet should remain in contact with the baseboard thus
preventing strain due to rocking caused, for instance, by operation of the reset
Where two or three meters axe to be located together, they should be of the same type
suitably mounted and labelled for identification (see TIs C3 E5001 and F2500 for
To test the operation of a subscriber's private meter, a call should be dialled to a test
number in the local exchange or a nearby exchange; this should cause the meter to register
one unit when inverted ring tone is connected. In director exchanges it is necessary to
use a test number circuit returning a permanent loop (i.e. that previously known as a
"multi-metering test number"). The test call may be repeated a few times if
considered necessary to confirm the result. The number of test calls made should be
carefully noted and advised to the Maintenance Control so that the subscriber's account
may be suitably credited. Calls on which the private meter fails to operate must not be
held (for example, for tracing in the exchange) because of the uncertainty regarding
registration which may be continuing periodically on the exchange meter.
Attempts must not be made to gain access to any component or to any part of the mechanism.
Only a change of cord is permissible. Any meter which fails to work satisfactorily should
be returned to the Supplies Dept using the normal procedure for the return of faulty
Because of the delicate mechanisms in these meters they should be handled with care at
all times and transported only in the packing boxes in which they are supplied.
The presence of the meter does not affect the normal line test condition.