UL 508A - Ampacities of Conductors
Insulated conductors and control circuit conductors according to UL 508A
The size of insulated conductors inside an industrial control panel cannot be smaller than 14 AWG. Actually, for Industrial Machineries, for low rated power motors, even size of conductors smaller than AWG 14 can be used inside the control panel (Table 66.1A).
The sizing of the conductors inside the control panel must be carried out as follows: the FLC must be increased by 25%: this is the minimum ampacity the conductor must have.
The ampacities of the conductors inside the control panel are stated in Table 28.1 of UL 508A. Furthermore, for multiple-conductors (3 cables maximum), the ampacity must be reduced.
Control circuit conductors may have size smaller than 14AWG, according to Table 38.1.
In the US it is also mandatory to use conductors that can withstand 90°C, but inside the control panel they must not generally exceed 75°C.