Electrical energy is the isolation task with the smallest margin for error. Across US workplaces, contact with electricity causes around 150 deaths a year, and roughly 5,180 electrical injuries serious enough to cost days away from work were recorded across 2023 and 2024, according to the Electrical Safety Foundation International drawing on BLS and OSHA data. The detail that should change how you think about this: about 70% of those fatalities happen to workers in non-electrical occupations. Most people killed by electricity at work aren't electricians. They're maintenance technicians, machine operators, and contractors who didn't expect a live circuit to be part of the job.
That's exactly the gap electrical lockout/tagout exists to close. Done properly, it removes the assumption from the work. Nobody has to trust that a circuit is dead, because the procedure forces them to prove it. This guide walks the electrical isolation process step by step, with the weight where it belongs: on controlling stored energy and verifying a zero-energy state before anyone touches a conductor.
Two distinct hazards make the rigour worth it. Shock comes from a worker becoming part of the circuit. Arc flash is the sudden release of energy when a fault jumps across conductors, producing heat and pressure that can injure someone who never makes direct contact. De-energising the equipment and proving it dead removes both, which is the core reason isolation beats working live wherever de-energising is feasible.
## When electrical LOTO applies, and the rules behind it
Electrical lockout/tagout sits across three layers of requirement, and it helps to know which does what.
OSHA's general energy-control standard, 29 CFR 1910.147, governs the isolation of hazardous energy during servicing and maintenance, electrical sources included. For electrical work specifically, 29 CFR 1910.333 sets the safe work practices. It requires that circuits be de-energised before an employee works on or near them, and that the de-energisation be verified rather than assumed. Sitting alongside both is NFPA 70E, the consensus standard for electrical safety in the workplace. NFPA 70E isn't law in the way the OSHA standards are, but OSHA treats it as a recognised method for meeting the general duty to protect workers, so it's the practical benchmark most employers work to.
Electrical LOTO is required whenever someone services or maintains equipment and contact with electrical energy, or the unexpected re-energisation of a circuit, could injure them. There's a narrow exception for work where de-energising introduces greater hazard or is genuinely infeasible, but that route demands a qualified person, an energised-work permit, and a strict set of precautions. For the overwhelming majority of maintenance tasks, the safe and compliant answer is to isolate and lock out.
## Who is qualified to do the work
Electrical LOTO draws a sharper line around competence than most isolation tasks. OSHA distinguishes a qualified person, someone trained to recognise and avoid the electrical hazards involved and to work safely on or near exposed parts, from an unqualified person who isn't. Verifying the absence of voltage in particular has to be done by a qualified person using suitable test equipment.
That maps onto the wider lockout/tagout roles. Authorised employees apply the locks and tags and perform the isolation. Affected employees operate or work near the equipment but don't carry out the lockout. Other employees only need to know a lockout is in force and leave it alone. For electrical work the authorised employee usually needs to be a qualified person too, because the isolation and verification steps demand it.
Training underpins all of this. 29 CFR 1910.332 sets out the training requirements for employees who face electrical risk, and NFPA 70E expands on the qualification and retraining detail. The practical test is straightforward: the person isolating and verifying the circuit should understand the equipment, the hazard, and the limits of their own authorisation.
## The electrical lockout/tagout procedure, step by step
An electrical LOTO procedure follows the same backbone as any energy isolation, with extra care at two points. Here's the sequence.
First, notify everyone affected that the equipment is coming down and why. Second, shut the equipment down through its normal stopping process rather than simply pulling the supply. Third, isolate the energy at the disconnecting means, the breaker or fused disconnect that actually breaks the circuit, not just a local control switch. Fourth, apply your lock and tag to the disconnect so it can't be re-closed. Fifth, control any stored or residual electrical energy, which is the step covered in detail below. Sixth, verify the absence of voltage before treating the circuit as safe.
Releasing the lockout reverses the logic with the same discipline. Inspect the work area and confirm tools and people are clear, make sure everyone is positioned safely, then remove the devices and notify affected workers before the circuit is re-energised. Our [pre-execution and post-execution checklist](/resources/blog/loto-execution-checklist-pre-execution-and-post-execution-checks) breaks this down into the checks that stop steps being skipped under time pressure.
## Stored and residual electrical energy
This is the first place electrical work diverges from a simple mechanical isolation. Opening a disconnect stops energy flowing in, but it doesn't guarantee the circuit is at zero. Several sources can hold a lethal charge after the supply is cut.
Capacitors store energy by design and can stay charged for a meaningful time after disconnection, which is why many require a deliberate discharge before work. Variable-frequency drives, large power supplies, and UPS systems can all retain dangerous energy internally. And then there's backfeed, where a circuit you've isolated is still being energised from somewhere else: an alternate supply, an on-site generator, a control transformer, or a solar array feeding back through an inverter. Battery banks deserve particular attention, because they can't be switched off the way an incoming supply can, and they hold their energy regardless of what the main disconnect is doing.
The practical defence is to know the equipment before you isolate it. An accurate single-line diagram and a complete list of every energy source feeding the circuit is what separates a controlled isolation from a near miss. Where the equipment is complex, the isolation points belong in a documented, machine-specific procedure rather than in an individual's memory. Our guide to [writing a machine-specific LOTO procedure](/resources/blog/how-to-write-a-machine-specific-loto-procedure-step-by-step) covers how to capture that detail in a way the next person can follow.
## Verifying the absence of voltage
If electrical LOTO has a single defining step, this is it. Before anyone treats a circuit as safe, a qualified person has to test it and confirm there's no voltage present.
The method matters as much as the act. 29 CFR 1910.333 calls for a qualified person to use test equipment to check the circuit elements and confirm they're de-energised. Good practice, and the approach NFPA 70E sets out, is the live-dead-live test: prove the meter works on a known live source, test the conductors you're about to work on and confirm they read dead, then prove the meter still works on the known live source afterwards. That last step catches the rare but deadly case of a meter that failed partway through and gave a false dead reading. On higher-voltage systems the qualified person should also confirm the test instrument is rated for the voltage present and in good condition before relying on it. None of this takes long, but it's the difference between an assumption and a fact, and on an electrical circuit that distinction is the entire job.
This is the step that turns "the breaker's off" into "the circuit is safe." It's also the step most exposed when work is rushed, because it's tempting to skip when someone is confident the right breaker was opened. Confidence isn't verification. Building the test-before-touch step into the procedure, and recording that it happened, is how you make it non-negotiable.
## Locking out panels and disconnects
A few practical points come up again and again on the floor. Lock the disconnecting means itself, not just a breaker handle that can be overridden. Where a single device can't accept a lock directly, use a panel or breaker lockout device designed for that fitting rather than improvising. On motor control centres and shared panels, more than one circuit may need isolating for a single task, so confirm you've covered every source feeding the work.
When several people work under the same isolation, each one applies their own lock, so the equipment can't be re-energised until the last person has finished and removed theirs. That principle, one worker one lock, is what keeps group electrical work honest. We cover the coordination side of that in our guide to [managing multi-person LOTO without losing visibility](/resources/blog/group-lockouttagout-how-to-manage-multi-person-loto-without-losing-visibility).
## Documenting and proving it
Electrical LOTO compliance comes down to two questions an auditor or an incident investigation will ask. Can you produce the correct procedure for this specific piece of equipment, listing every energy source and isolation point? And can you show that the steps, especially the verify step, were actually carried out, by a qualified person, in the right order?
Paper struggles with the second question. A signed checklist in a folder tells you a form was filled in, not that the circuit was tested dead. A digital energy-isolation system closes that gap by holding machine-specific electrical procedures that can't drift out of date unnoticed, and by capturing each step as it's completed in an audit log that shows who did what and when. That record is what lets you prove the verify step happened, every time, rather than hoping it did. If you're newer to the concept, our overview of [how digital lockout/tagout works in practice](/resources/blog/what-is-digital-loto-how-digital-lockouttagout-works-in-practice) is a good starting point, and you can see how the full isolation lifecycle fits together on our [lockout/tagout platform page](/lockout-tagout).
Electrical procedures also need to stay current. Equipment gets modified, supplies get added, and a procedure that was accurate a year ago can quietly fall out of step with the panel it describes. The annual periodic inspection that 1910.147 requires is what catches that drift, and it applies to your electrical procedures as much as to any other. Our piece on running a [periodic LOTO review that proves procedures work](/resources/blog/periodic-loto-review-prove-procedures-work) covers how to keep them trustworthy over time.
Electrical energy doesn't give second chances the way some hazards do. The procedures that keep people safe aren't complicated, but they depend on being followed in full and proven afterwards. That's a discipline worth building into the system rather than leaving to the moment.
---
*Written by Matthew Nugent, co-founder of Zentri. A chemical engineer with ten years of industrial process operations experience, Matthew works on closing the gap between how energy-control procedures are written and how they actually hold up on the floor.*
