shall be suitable for [125] [____] volts dc and shall reset when the
breaker is reset.]
2.2.1
Trip Units
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NOTE: Both thermal magnetic and solid state trip
units have been included in this specification.
Solid state units can be more reliable and permit
more selective coordination since they can have long
time pick-up, long time delay, short time pick-up,
short time delay, instantaneous pick-up, ground
fault pick-up, and ground fault time delay settings.
Solid state units have come down in price and are
becoming competitive with thermal magnetic units.
Specific locations where solid state trips are
required should be indicated on the drawings.
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Except as otherwise noted, the circuit breakers, of frame sizes and the
trip unit ratings as shown on the drawings, shall be provided with
combination thermal and instantaneous magnetic or solid state trip units.
The Government reserves the right to change the indicated trip ratings,
within frame limits, of the trip devices at the time the shop drawings are
submitted for approval. The breaker trip units shall be interchangeable
and the instantaneous magnetic trip units shall be adjustable on frame
sizes larger than 150 amperes. Nonadjustable instantaneous magnetic trip
units shall be set at approximately 10 times the continuous current ratings
of the circuit breakers. [Solid state trip units, where indicated, shall
also have adjustable [long time pick-up and delay],[short time pick-up and
delay], [and ground fault pick-up and delay].]
2.2.2
480-Volt AC Circuits
Circuit breakers for 480-volt or 277/480-volt ac circuits shall be rated
600 volts ac, and shall have an UL listed minimum interrupting capacity of
[14,000] [_____] symmetrical amperes at 600 volts ac.
2.2.3
120/240-Volt AC Circuits
Circuit breakers for 120-volt ac circuits shall be rated not less than
120/240 or 240 volts ac, and shall have a UL listed minimum interrupting
capacity of [10,000] [_____] symmetrical amperes.
2.2.4
125-Volt DC Circuits
Circuit breakers for 125-volt dc circuits shall be two-pole rated 125/250
or 250 volts dc, and shall have an UL listed minimum interrupting capacity
of [5,000] [10,000] [_____] amperes dc.
2.3
WIRING
All control wire shall be stranded tinned copper switchboard wire with
600-volt flame-retardant insulation Type SIS meeting UL 44 or Type MTW
meeting UL 1063, and shall pass the VW-1 flame tests included in those
standards. Hinge wire shall have Class K stranding. Current transformer
secondary leads shall be not smaller than No. 10 AWG. The minimum size of
control wire shall be No. 14 AWG. Power wiring for 480-volt circuits and
below shall be of the same type as control wiring and the minimum size
SECTION 16403A
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