INFORMATION & REQUIREMENTS ELECTRIC SERVICE - NStar

ARTICLE 802
suitability of the proposed equipment for operation at the
intended location. Attempting to operate a motor at other
than its nameplate characteristics will result in
unsatisfactory performance and, in certain instances, could
cause injury to personnel and/or damage to equipment.
B. Limitation of Motor Size
NSTAR reserves the right to refuse service to the following:
1. Single phase motors larger than 5 hp. Single phase motors
of larger rating may be permitted, provided NSTAR’s
facilities are adequate to supply the service and provided
the use of such motor or motors does not interfere with
the quality of service rendered to other customers.
2. Polyphase motors larger than 5 hp operated from a single
phase service by use of a phase converter.
3. Motor installations aggregating less than 7 hp would
typically be a single phase installation. Specific permission
from NSTAR will be required in all cases involving
polyphase motors of less than 7 hp.
4. NSTAR further reserves the right to limit the size of the
largest motor, which may be operated on any part of the
system.
C. Single Phase Motors
1. 120 Volt Supply – Motors with rating of 1/2 hp or less and
window-type air conditioning units whose running load
current does not exceed 7 amperes, with not more than
forty starts per hour and with a locked rotor current not
exceeding 50 amperes, may be connected to 120 volt supply.
Motors having a full load running current of more than 7
amperes but less than 12 amperes, and conforming to the
above locked rotor current limitations, may be connected
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ARTICLE 802
to a 120 volt branch circuit only if such branch circuit
supplies the one unit and does not supply lighting units
or other appliances. It is strongly recommended that
units drawing more than 7 amperes full-load running
current be connected to 240 or 208 volt circuits.
2. 208 or 240 Volt Supply – Motors with ratings larger than
1/2 hp but less than 5 hp will be regularly supplied at
208 or 240 volts, provided the locked rotor current does
not exceed the values given in Table No.1. In
predominantly residential areas, and for small
commercial installations, the NSTAR New Customer
Connect Tech Center should be contacted before
installing motors with ratings over 2 hp.
3. Maximum Locked Rotor Currents – Single phase motors
supplied from combined light and power secondary
systems shall not have locked rotor current values in
excess of those shown in Table No. 1. Motors having
locked rotor current values in excess of those shown in
the table shall be equipped with starters, which will limit
the current to the values specified. Domestic laundry
equipment, with operating cycles and electrical
characteristics as currently available, is considered
acceptable.
Motors that start more than four times per hour are an
exception to the above and may cause interference to
other customers. Automatically and frequently started
motors for general use, such as motors for refrigerators,
oil burners, and similar devices shall not have a locked
rotor current exceeding 23 amperes at 120 volts or 29
amperes at 240 volts. For multi-motored devices
arranged for starting of motors one at a time, the locked
rotor current limits shall apply to the individual motors.
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