9 defines control wiring colors: black for supply voltage, red for AC control < supply, blue for DC control, yellow for foreign voltage. But I have some 12 VAC and some 24 VAC stuff as well as some 12 VDC battery stuff also and not sure what colors to use for the 12 and 24 VAC and what color to ise for the 12 VDC battery wires? Rob. From UL508A, I assume this is the panel standard you're working to. a) Black – all ungrounded. Understand the standard colors in PLC for identifying devices and systems in industrial automation projects effectively. When you are working on industrial automation projects, there are a lot of standard devices, cables, and systems which are required to be defined properly according to their. All About Circuits outlines the wiring color code standards and conventions, showing how different parts of the world incorporate colors for single-phase, three-phase, and direct current (DC) systems. It is worth noting that some of these colors have changed, so the age of a building and its wiring. This sub is dedicated to discussion and questions about Programmable Logic Controllers (PLCs): "an industrial digital computer that has been ruggedized and adapted for the control of manufacturing processes, such as assembly lines, robotic devices, or any activity that requires high reliability. The choice of cable colour initially depends on what type of circuit it is, and whether the voltage is AC or DC. The wire used for the protective conductor (earth) must be GREEN-AND-YELLOW. 9 (listed in UL 508A Industrial Control Equipment, 3rd Edition) provides explicit color coding requirements for internal control wiring in UL 508A listed panels.