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what is a manhole where both transmission and distro ducts terminate is called what
a T & D manhole
in an area where it is necessary to avoid disrupting streets and lawns it is most likely that the cable will be ?
buried with guided underground boring
on underground systems it is more costly to locate and repair faults when?
compared to overhead systems
ducts running from manhole to manhole can be made of?
concrete
primary cables cant be buried in the same trench with secondary cables
false
the term "joint construction" of a pole or an underground system refers to an installation where several utilities share the facilities but not the cost
false
advantages of underground systems compared to overhead are?
less vulnerable to damage from wind, ice and cars. more aesthetically pleasing, safer for the public
when are underground systems commonly used?
the appearance of overhead lines is undesirable. the hazard of exposed high voltage lines is too great. space is not available for overhead lines.
a disadvantage of underground systems compared to overhead is that
theyre more expensive to build
accidental dig ins, corrosion or chemical action, and earthquakes are potential problems that damage underground systems
true
fault indicators minimize the duration of outages because they aid in finding the trouble location
true
loop type feed design makes it possible to restore service to certain customers while making cable repairs
true
some underground cables may be burried directly in the ground with only an envelope of sand around them
true
the direct bury system is used mostly in underground residential distro systems
true
the underground riser provides fused protection and an isolating device for the underground cable
true
ducts for transmission lines are sometimes referred to as?
trunk ducts or subterranean feeders
the letters URD stand for?
underground residential distribution
what is oil or gas filled cable used to permit
underground transmission conductors with line voltages up to 500kilovolts
can a pad mounted transformer be used in URD
yes
can a system have sections of overhead and underground or not?
yes
