Cal. Code Regs. Tit. 8, § 2735 - Overcurrent Protection
(a) Feeders and branch circuit conductors
shall have overcurrent protection in each ungrounded conductor located at the
point where the conductor receives its supply or at a location in the circuit
determined under engineering supervision.
(1)
Circuit breakers used for overcurrent protection of three-phase circuits shall
have a minimum of three overcurrent relays operated from three current
transformers. On three-phase, three-wire circuits, an overcurrent relay in the
residual circuit of the current transformers may replace one of the phase
relays. An overcurrent relay, operated from a current transformer that links
all phases of a three-phase, three-wire circuit, may replace the residual relay
and one of the phase-conductor current transformers. Where the neutral is not
grounded on the load side of the circuit, the current transformer may link all
three phase conductors and the grounded circuit conductor (neutral);
and
(2) If fuses are used for
overcurrent protection, a fuse shall be connected in series with each
ungrounded conductor;
(3) Each
protective device shall be capable of detecting and interrupting all values of
current that can occur at its location in excess of its trip setting or melting
point.
(4) The operating time of
the protective device, the available short-circuit current, and the conductor
used shall be coordinated to prevent damaging or dangerous temperatures in
conductors or conductor insulation under short-circuit conditions;
and
(5) The nominal rating of the
cables will be as required by Section
2821.
(b) The following additional requirements
apply to feeders only:
(1) The continuous
ampere rating of a fuse shall not exceed three times the ampacity of the
conductors. The long-time trip element setting of a breaker or the minimum trip
setting of an electronically actuated fuse shall not exceed six times the
ampacity of the conductor.
EXCEPTION FOR FIRE PUMPS: Conductors may be protected for short circuit only.
(2)
Taps to a feeder need not have separate fault protective devices, provided that
the conductors are capable of withstanding the maximum short circuit current
that can occur for the time necessary for a fault protective device on the
source side of the conductors to operate.
Notes
2. Amendment of section and NOTE filed 4-1-2009; operative 4-1-2009. Submitted to OAL for printing only pursuant to Labor Code section 142.3 (Register 2009, No. 14).
Note: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.
2. Amendment of section and Note filed 4-1-2009; operative 4-1-2009. Submitted to OAL for printing only pursuant to Labor Code section 142.3 (Register 2009, No. 14).
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