6-9. Air Force Installations.
ing conductors of dissimilar metals. The need for
an interference-free environment may also necessi-
a. Reclosers and sectionalizers. Reclosers and
sectionalizers shall be fully rated and coordinated.
radio noise suppression. Valve-type lightning ar-
Electronically controlled reclosers are preferred
over hydraulically controlled ones. Reclosers may
should be avoided. If required to suppress radio
utilize vacuum or oil as the interrupting medium.
interference, utilize underground construction with
Sectionalizers shall be automatic loadbreak, man-
ual recock, and installed only as an integral part
metal enclosures. High intensity discharge (HIS)
of the system protection scheme. They should not
lamps are also sources of high radio interference
be installed for switching purposes only. Stirrups
while filament lamps and low pressure sodium
should be installed as appropriate to prevent dam-
lamps are basically free of radio noise.
age to main conductors at junction poles.
c. Arresters. Distribution class is preferred; con-
b. Radio interference. Where suppression of ra-
sideration should be given to gapless types such as
zinc oxide, metal oxide varistor (MOV).
shall be given to contacts between current carry-