HANDBOOK REQUIREMENTS - Central Maine Power Company

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double-throw switch or other transfer device
which meets all
of the following requirements shall be used.
A. When service is transferred, it must be so arranged as to
open all ungrounded conductors from the normal supply
from the Company before any connection is made to the
emergency or standby supply.
B. The double-throw switch or transfer device must be so
constructed and connected as to positively prevent any
possibility of power from the customer's emergency source
feeding back into the Company's distribution system.
C. A sign/label shall be placed at the service entrance
equipment (as prescribed by the NEC) indicating the type
and location of the on-site emergency or standby power
sources. CMP highly recommends this sign/label be placed
conspicuously outside of the building on the service
entrance equipment or meter enclosure.
When it is desired to energize all of the customer's
distribution circuits from the emergency or standby source,
the above switch may, if acceptable to the "authority having
jurisdiction," be connected on the line side of the regular
service disconnecting means; provided, in accordance with
the NEC, the equipment is marked as “suitable for use as
service equipment” and is installed per its “listing.”
Additionally, for the case of automatic transfer, there must
be a manual disconnecting means (suitable for use as
service equipment) on the line (CMP) side of the autotransfer
device. This disconnect may be an integral part of
the transfer device. Where equipment is exposed to the
weather, it must be of a raintight construction.
Conductors that may be energized by emergency or
standby generating equipment shall not be located in the