f.
Instantaneous current pick-up, adjustable from 1.5 to 9 times
long-time current setting.
g.
Ground-fault pick-up, adjustable from 20 percent to 60 percent of
sensor rating, but in no case greater than 1200 amperes. Sensing
of ground-fault current at the main bonding jumper or ground strap
shall not be permitted. [Zone-selective interlocking shall be
provided as shown.]
h.
[Fixed] [Adjustable] ground-fault delay.
i.
[Ground-fault I square times t switch.]
j.
[Overload] [and] [Short-circuit] [and] [Ground-fault] trip
indicators shall be provided.
2.8.7
Current-Limiting Circuit Breakers
Current-limiting circuit breakers shall be provided as shown.
Current-limiting circuit breakers shall limit the let-through I square
times t to a value less than the I square times t of one-half cycle of the
symmetrical short-circuit current waveform. On fault currents below the
threshold of limitation, breakers shall provide conventional overload and
short-circuit protection. Integrally-fused circuit breakers shall not be
used.
2.8.8
SWD Circuit Breakers
Circuit breakers rated 15 amperes or 20 amperes and intended to switch 277
volts or less fluorescent lighting loads shall be marked "SWD."
2.8.9
HACR Circuit Breakers
Circuit breakers 60 amperes or below, 240 volts, 1-pole or 2-pole, intended
to protect multi-motor and combination-load installations involved in
heating, air conditioning, and refrigerating equipment shall be marked
"Listed HACR Type."
2.8.10
Motor Circuit Protectors (MCP)
**************************************************************************
NOTE: A motor circuit protector (MCP) is defined as
an adjustable, instantaneous trip circuit breaker
used in conjunction with a combination motor
controller having overload protection.
**************************************************************************
Motor circuit protectors shall conform to NEMA AB 1 and UL 489 and shall be
provided as shown. MCPs shall consist of an adjustable instantaneous trip
circuit breaker in conjunction with a combination motor controller which
provides coordinated motor circuit overload and short-circuit protection.
Motor Circuit Protectors shall be rated in accordance with NFPA 70.
2.9
LOW-VOLTAGE POWER CIRCUIT BREAKERS
2.9.1
Construction
Low-voltage power circuit breakers shall conform to IEEE C37.13, ANSI C37.16,
and NEMA SG 6 and shall be three-pole, single-throw, stored energy,
SECTION 16475A
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