When connected to multi-wire branch circuits, what must happen to all supply conductors of the ballast?

When dealing with multi-wire branch circuits connected to ballasts, it is essential that all supply conductors are simultaneously disconnected. This requirement is rooted in ensuring safety during maintenance or repair work. If only one conductor is disconnected, there is a risk that the remaining conductors could still be live, potentially leading to electrical shock or equipment damage when technicians are working on the circuit.

By requiring that all supply conductors be broken at the same time, the National Electrical Code aims to prevent any hazardous conditions where one part of the circuit might still be energized. This rule enhances safety for individuals servicing the lighting fixtures powered by these circuits. It acknowledges the interconnected nature of multi-wire branch circuits and the necessity of ensuring a complete disconnection to avoid any risks associated with partial power being present.