"Lockout/Tagout" gets shortened so often that it's easy to forget it's actually LOTOTO - Lockout/Tagout/Tryout - and that third word is doing real work. It's what separates NFPA 70E's procedure from a bare-minimum reading of OSHA's LOTO rule, by explicitly requiring the worker to test for absence of voltage rather than trust that isolation worked. The full procedure runs eight steps, in order, and skipping ahead - not skipping steps entirely, just doing them out of sequence - is where most real-world mistakes happen.
Steps 1-3: before anything gets touched
Identify all energy sources - not just the obvious main feed, but control power, battery backup, stored energy in capacitors or inductors, gravity on a lifted load, pneumatic or hydraulic pressure, and spring-loaded mechanisms. Missing one of these is the single most dangerous failure mode in the whole procedure, because everything downstream of it assumes the list is complete. Notify affected employees so nobody is caught off guard by the shutdown or tempted to re-energize out of confusion - coordination failures here are how "who turned that back on?" incidents happen. Identify the disconnecting means - the specific breaker, disconnect, or isolation point for each energy source you just identified, confirmed before you touch anything.
Steps 4-6: taking control
Apply PPE before operating the disconnect. Opening a disconnect under load can itself cause an arc flash, so the PPE goes on before that switch moves, not after - this step exists because the act of de-energizing is itself a hazardous operation, not a safe prelude to one. De-energize the equipment, following any procedural steps specific to that gear - reducing load first, or racking out a breaker, for example. Lock and tag every disconnecting means that was operated. Every worker on the job applies their own personal lock - not one lock shared across a crew. A tag by itself is a warning sign, not a physical barrier - it doesn't stop anyone from operating the disconnect, it only tells them not to.
Steps 7-8: the parts people skip
Release or restrain stored energy. Zero electrical input isn't the same as zero energy - capacitors still need discharging, hydraulic pressure still needs bleeding, suspended loads still need blocking, spring tension still needs relieving. Equipment that's electrically dead but mechanically still loaded can move, discharge, or fall. Verify absence of voltage - the "tryout." Test your meter on a known live source first to confirm it works, test the equipment, then test the meter on the known live source again to confirm it still works. That live-dead-live sequence exists because a meter can fail silently mid-test, and if it did, everything you measured after that point wasn't actually verified - it just looked verified.
Putting locks back on isn't the reverse of taking them off
Before removing locks to restore power: confirm tools and materials are clear, confirm all workers are clear, notify everyone affected - then each person removes only their own lock. The last lock off is the authorization to re-energize, not a formality at the end of the shift. If a lock's owner isn't available to remove it themselves, that's an abandoned-lock situation with its own procedure, not something a supervisor just cuts off.
The full eight-step sequence with exam-style traps (checking only the line side, treating IP20-protected equipment as "safe," skipping the second meter check) is in the Study Guide, with practice questions in the Exam Companion.