I am going to be replacing 15kv and 35kv switchgear located adjacent to the local utility company yard which feeds it. The existing gear has 2-4/0 equipment grounds going to each ( 15kv and 35kv) and is connected to the ground grid. The drawings I have for replacing the gear shows installing 1 - #6 ground wire to each section for equipment grounding. My experience with medium voltage is limited. Does this seem correct going from 4/0 to #6? I appreciate any input.
Thanks
250.66 Size of Alternating-Current Grounding Electrode
Conductor. The size of the grounding electrode conductor at
the service, at each building or structure where supplied by a
feeder(s) or branch circuit(s), or at a separately derived system
of a grounded or ungrounded ac system shall not be less than
given in Table 250.66, except as permitted in 250.66(A)
through (C).
(A)
Connections to a Rod, Pipe, or Plate Electrode(s). If the
grounding electrode conductor or bonding jumper connected
to a single or multiple rod, pipe, or plate electrode(s), or any
combination thereof, as described in 250.52(A)(5) or (A)(7),
does not extend on to other types of electrodes that require a
larger size conductor,
the grounding electrode conductor shall
not be required to be larger than 6 AWG copper wire or 4 AWG
aluminum wire.
