Western Electric Catalogue #1 - Wedophones.com wedophones

N o . 13
No . 12-A
Code No .
WESTERN ELECTRIC COMPANY
PLUG SEATS
Mounted on
Centers
inches
Red Fibre
PROTECTION
The complete protection of telephone apparatus from foreign electrical currents which might cause
damage by fire or injury from electrical shock requires the use of high potential, abnormal current and
sneak current arresters . These arresters should be installed (1) at central offices, (2) at cable terminals,
and (3) at telephone stations .
All lines entering the central office should be equipped with heat coils or sneak current
Central Offices arresters . In case the lines outside the central office are wholly underground, or of
non-exposed, insulated wire, no protection other than heat coils is necessary . In case
the lines leave the central office in underground cable but are exposed, carbon block cutouts should be
installed in addition to heat coils . In case the lines are distributed immediately to open lines, heat coils,
carbon block cutouts and No . 7-A fuses should be provided .
When open wire lines enter the central office and at any portion of their length are exposed to potentials
in excess of 2,500 volts, the protection noted above should be used and, in addition, metal block cutouts
should be installed at the outer end of the bridle cable .
Cable terminals should be located at the outer end of underground cable and equipped
Cable Terminals with No . 7-A fuses . If the lines are connected to aerial cable or open wires in localities
where lightning is not very prevalent, and if they are not exposed to foreign electrical
circuits this protection is sufficient, provided the lines are less than one-half mile in length . Under these
conditions if the lines are over one-half mile long, copper block cutouts should also be used . Carbon block
cutouts should be installed if the lines are exposed to other electrical circuits . If the lines are not exposed
to other circuits copper block cutouts should be used if the lines are over one-half mile in length or if they
are in districts where lightning is very severe .
In case the line from the central office to a telephone station is wholly underground
Telephone Stations or of non-exposed, insulated wire, no protection need be installed at the telephone
station .
If the lines are wholly or in part of open wire, and exposed to circuits not in excess of 1800 volts, the
No . 12-A protector should be used at magneto stations and the No . 58-A or Nos . 59-A and 60-A at central
battery telephone stations . If the lines are not exposed to other circuits the No . 58-B or the Nos . 59-A
and 60-B may be used at central battery and magneto stations respectively .
In case the lines are exposed to lighting or power circuits in excess of 1800 volts, or to severe lightning
discharges, the No . 47 type fuse should be employed at the telephone stations . These are outside fuses
to be connected in the drop wire and are so constructed that if an are persists after the fuse blows, the tube
will be shattered and the wire will fall away by several feet, thus effectually opening the line .
When the exposed line is not more than one-half mile long, the No . 47-A, 7 ampere fuse, may be
employed in connection with the No . 60-A protector . In case the exposed line is more than one-half mile
long the No . 47-B, 14 ampere fuse, may be used in connection with the No . 79-A protector .
For code numbers of fuses, protector blocks and protector
micas, see tables having these headings .
WRITE FOR LIBERAL DISCOUNTS
Used with
Plugs
number
PROTECTORS
MOUNTED SINGLY
57
List Price
each
12 110 $0.015
13 109 .015
15 s 47,116 .015
Code No . Used with
Protecting
against Consists of
List Price
each
12-A Magneto tele- High poten- 2 7-ampere fuses
phone sets tial, abnormal with heat coils, 2
and sneak cur- carbon cutouts
rents and mounting . . . . $ 1 .22