boards that are manufactured by other companies, the line and cut-off
relays are mounted on separate racks outside the switchboard room and
adjacent to the main and intermediate distributing frames, the wiring
being extended from the relays to the jacks and lamps on the switchboard
proper by means of suitable cables. The Western Electric Company has
recently instituted a departure from this practice in the case of some
of their smaller No. 1 switchboard installations. Where it is thought
that the ultimate capacity required by the board will not be above 3,000
lines, the relay rack is dispensed with and all of the line and cut-off
relays, as well as the supervisory relays, are mounted in the rear of
the switchboard frame. For this purpose the line and cut-off relays are
specially made with the view to securing the utmost compactness. In
still other cases, in switchboards of relatively small ultimate
capacity, they use this small line and cut-off relay mounted on a
separate relay rack, in which case the board is the standard No. 1 board
except for the type of relays. In all of these modifications of the No.
1 board adapted for the use of the smaller and cheaper relays, the line
relay has but a single winding, the small size of the relay winding not
lending itself readily to double winding with the added necessary coil
terminals.

_Capacity Range._ The No. 1 Western Electric board is made in standard
sizes up to an ultimate capacity of 9,600 lines. For all capacities
above 4,900 lines, a 3/8-inch jack, vertical and horizontal face
dimensions, is employed. For this capacity the smaller types of cut-off
and line relays are not employed. Up to ultimate capacities of 4,900
lines, 1/2-inch jacks are employed, and either the small or the large
relays mounted on a separate rack are available. Up to 3,000 lines
ultimate capacity, the 1/2-inch jack is employed, and either the small
or the large cut-off and line relays are available, but in case the
small type is used the purchaser has the option of mounting them on a
separate relay rack, as in ordinary practice, or mounting them in the
switchboard cabinet and dispensing with the relay rack.

=Western Electric No. 10 Board.= The No. 1 common-battery multiple
switchboard, regardless of its size and type of arrangement of line and
cut-off relays, involves two relays for each line, the line relay
energized by the taking of the receiver off its hook, and the cut-off
relay energized b