Table 4. Size of holes required to pass station wire through floors and walls.
Fastening wire and cable in buildings.
a. Where facilities are not provided for concealed wiring, such as an underfloor duct systems,
base raceways, mouldings, fasten the wire to the walls along baseboards, chair rails, door frames,
window trim, and so far, where it will not be subject to mechanical injury. In the case of wooden
baseboards, however, fasten wire to the baseboard, either along its top or in the groove. Where marble,
steel, or concrete baseboards are encountered, always place a nail or screw behind the baseboards and
into the plaster. Never fasten wires directly to conduits or pipes or to their supports.
b. Fastening line wire, exposed station. Between point of entrance and protector: Line wires
between the point of entrance and the protector must neither touch nor be movable into permanent
contact with any combustible or electric-current-conducting materials or objects except where wires
enter through a service conduit. If the number of wire runs installed on C-knobs increases to more than
two, remove the knobs and place the wires in insulated screw eyes. Space fastening devices at the
approximate distances shown in Figure 51.