Energy isolating device
A mechanical device, such as a disconnect switch, valve or block, that physically stops energy from reaching equipment.
Definition, in the source's words
29 CFR 1910.147(b)(opens ecfr.gov in a new tab)“Energy isolating device. A mechanical device that physically prevents the transmission or release of energy, including but not limited to the following: A manually operated electrical circuit breaker; a disconnect switch; a manually operated switch by which the conductors of a circuit can be disconnected from all ungrounded supply conductors, and, in addition, no pole can be operated independently; a line valve; a block; and any similar device used to block or isolate energy. Push buttons, selector switches and other control circuit type devices are not energy isolating devices.”
What it means
The test is physical isolation. Control-circuit devices only send a signal, so a fault or a second operator could still start the machine. That's why the definition excludes them by name.
Example
A press has a stop button on the control panel and a fused disconnect on the wall. Only the disconnect is an energy isolating device; the lock goes there, never on the stop button.
Where it appears on the exam
ASP: ASP11 Domain 2, Safety Programs and Concepts
Practice: Lockout/Tagout (Hazardous Energy)
CSP: CSP11 Domain 1, Advanced Application of Safety Principles
Practice: Confined Spaces and Lockout/Tagout
Questions
- Is an emergency stop button an energy isolating device?
- No. Push buttons, selector switches and other control circuit type devices are excluded by the definition.
Related
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