Under the rule, a disconnecting means is required for which scenario?

• A. All ungrounded conductors that supply multiple branch circuit devices sharing the same yoke or mounting strap
• B. All grounded conductors
• C. Any branch circuit that serves a single device
• D. Only in commercial installations

Answer: (A)

The rule is about providing a way to de-energize all live conductors that feed multiple branch-circuit devices when those devices share the same mounting strap or yoke. If several devices are mounted together on one strap, a single disconnecting means must be available to shut off all ungrounded conductors feeding those devices. This ensures safe servicing by removing all live power at once, rather than leaving part of the circuit energized.

Grounded conductors (neutrals) aren’t the focus of this requirement, since removing them doesn’t reliably guarantee a safe de-energization of the live conductors. And it isn’t limited to commercial installations; the rule applies in residential and other settings whenever multiple devices share a single strap.