Figure 4-33 shows an open types of distribution cutout
being closed. Distribution cutouts are used with
installations of transformers, capacitors, cable circuits,
and sectionalizing points on overhead circuits.
Enclosed Distribution Cutout
An enclosed distribution fuse cutout is one in which
the fuse clips and fuse holder are mounted completely
within an enclosure (fig. 4-34, view A). A typical
enclosed cutout has a porcelain housing and a hinged
door supporting the fuse holder. The fuse holder is a
hollow vulcanized-fiber expulsion tube. The fuse link is
placed inside the tube and connects with the upper and
lower line terminals when the door is closed. When the
fuse blows or melts because of excessive current
passing through it, the resultant arc attacks the walls of
the fiber tube, producing a gas that blows out the arc.
The melting of the fusible element of some cutouts
causes the door to drop open, signaling to the lineman
that the fuse has blown.
Open-link Distribution Cutout
This type of cutout differs from the open cutout in
that it does not use the fiber expulsion tube (fig. 4-34,
view B). The fuse link is supported by spring terminal
contacts. An arc-confining tube surrounds the fusible
element of the link. During fault clearing, the spring
contacts provide link separation and arc stretching. The
arc-confining tube is incorporated as part of the fuse
Open Distribution Cutout
Open cutouts are similar to the enclosed types,
except that the housing is omitted (fig. 4-34, view C).
The open type is made for 100- or 200-amp operation.
Some cutouts can be up rated from 100 to 200 amps by
using a fuse tube rated for 200-amp operation.
Lightning arresters are designed to permit normal
circuit operations at designed voltages, yet conduct any
potentially destructive higher voltage, such as lightning
Figure 4-33.Distribution cutout.