IEEE C37.21a:2020 pdf download.IEEE Standard for Control Switchboards Amendment 1: Control and Secondary Circuits and Devices, and All Wiring.
7.1.5.3.1 Wiring across a hinge
Wiring that crosses a hinge shall be suitable for this use, as defined by all of the following criteria:
a) The wire shall be sized according to 7.1.5.3.2. and
b) Single conductors shall be stranded wire, and
c) Wire shall be sufficiently flexible to withstand repeated door movement without sustaining damage to the wire strands or insulation, and
d) The loop formed by the wiring as it crosses the hinge shall be secured to the equipment at both ends, in such a manner that negligible strain is transmitted to wire beyond the securements to prevent damage to the wire insulation as the door is moved, and
c) Wiring shall not prevent the door from opening to the intended maximum opening, with a minimum opening of 90 degrees, and
The wire ioop is to be protected between the securements to provide a degree of protection against damage to the wire insulation as the door is moved, and
g) No sharp edges or objects are allowed in the path swept by the wire loop as the door is operated. and
h) If the wire is No. 14 AWG or larger wire, the wire shall be no less flexible than Class C or D stranding.
7.1 .5.3.2 Wire size
Wire shall be suitable for the anticipated maximum steady-state load. The size chosen should also accommodate voltage drop within the switchgcar. including the effect of intermittent heavy loads (shunt trip coils, inrush from relays. and the like). The following criteria shall be used as minimums.
Thermocouple wiring is specifically excluded from the above ampacity requirements. It shall meet the voltage, current, and temperature requirements of the circuit in which it is used and the location where it is insta lied.
When required for connection to a specific component, low-energy signaling, and communication wiring is specifically excluded from the above ampacity requirements. The wire shall meet the voltage, current, and temperature requirements of the circuit in which it is used and the location where it is installed.
NOTE—Where long connections to the control source are necessary, the cable must be large enough to prevent excessive voltage drop.
7.1.5.3.3 Wire protection and support
Bushings, grommets, or other mechanical protection shall be provided for wiring where it passes through a metal sheet, barrier, or raceway. Wiring shall be adequately supported to prevent stress from causing damage of any kind to the conductors or the insulation. Wiring for circuits operating at different voltages shall be separated unless all wiring is insulated for the highest operating voltage of all the circuits intended to be bundled or closely grouped.
7.1.5.3.4 Wire type
Wiring shall be rated for 600 V, 90 °C, be flame-retardant, and shall meet the requirements of NEMA WC7O / ICEA S-95-658. Preferred wire is type SIS as listed in the NFPA 70 (NEC®) or an equivalent such as XHHW, RFHH-2, RFHH-3, or the like. Other wires which meet the requirements of this clause are also acceptable.
Wiring used for connection directly on circuits above 600 V shall be rated for the voltage involved (or higher), 90 °C, and shall be flame-retardant.
In addition, wiring used for dc circuits for rated voltages of 48 V dc or above shall not contain PVC insulation.
EXCEPTION: In addition, low-energy signal wiring may be used as required by the manufacturer of a specific component. This exception includes wiring such as the following:
— Resistance Temperature Detectors (RTDs)
— Low-energy signal communication cables (e.g. RS232, RS485, Ethernet, fiber optic, and similar networking cables)
— Thermocouples
— Coaxial cables Ribbon cables
— Shielded twisted-pair
— Unshielded twisted-pair.IEEE C37.21a pdf download.