Lockout/Tagout (LOTO) in practice: energy isolation procedure, LOTO card and choosing lockout devices

In the EU, Directive 2009/104/EC on the use of work equipment requires maintenance to be carried out with equipment shut down and work equipment to have clearly identifiable means of isolation from each energy source that can be secured. Machine design guidance is given by EN ISO 14118 on prevention of unexpected start-up. In the US, OSHA 29 CFR 1910.147 — the origin of the lockout/tagout term — sets detailed requirements often adopted by global groups.

Electrical work has its own rules for preparing the workplace: disconnect, secure against reconnection, verify absence of voltage, earth and mark. National regulations transpose these principles differently.

This overview is for information only and is not legal advice. Requirements for a given machine follow from the employer's risk assessment and manufacturer documentation.

A LOTO card (energy isolation procedure) belongs to one machine or line. It shows a photo or diagram with numbered isolation points, a table of energy sources, the isolating device, the required lock and how to verify zero energy — such as testing for absence of voltage, reading 0 bar on a gauge or checking the ram is mechanically blocked.

A good card is short, visual and posted at the machine. Nobody should look for isolation points from memory or in a binder in the office. Maintenance and safety prepare the card together, and every modification — a new valve, an extra drive, a changed supply — requires an update.

In the example, a hydraulic press has four energy sources: 400 V supply, compressed air, hydraulics with a pressure accumulator and a ram that can drop under gravity. Missing any point means isolation is incomplete.

1. Prepare — identify the machine, open its LOTO card, determine all energy sources and notify operators and anyone whose work will stop.

2. Shut down — stop the machine normally according to its instructions without creating additional hazards (e.g. finish the cycle, clear the area).

3. Isolate — disconnect each energy source with an isolating device: main switch, isolation valve, gate valve. A STOP button, control switch or light curtain is not an isolating device.

4. Lock and tag — each person working on the machine applies their own padlock with a unique key and a tag with name, date and reason. With several isolation points or workers, use a multi-lock hasp or a group lock box.

5. Release stored energy — bleed pressure, vent air lines, discharge capacitors, block or lower raised parts, wait for rotating parts to stop and hot surfaces to cool.

6. Verify (try-out) — make sure nobody is in the danger zone and try to start the machine from the panel; test for absence of voltage, check gauges. Return the controls to off afterwards. Only now may work begin.

Return to service follows the reverse order: tools removed, guards refitted, people clear of the area, operators informed, locks removed — each lock only by the person who applied it.

LOTO padlocks are personal, one key per lock, often with a non-conductive shackle and a name label. Colours can identify departments (maintenance, electricians, contractors) — agree one scheme for the whole site.

Padlocks are combined with adapters: circuit breaker lockouts, plug lockouts, ball and gate valve lockouts, pneumatic coupling lockouts. A multi-lock hasp lets several people lock the same point. A group lock box is used for larger jobs: keys from the isolation-point locks go into the box and each crew member puts a personal lock on it.

A tag without a lock (tagout only) is merely a warning, not a physical barrier. It is used only where a device cannot be locked, with additional measures from the risk assessment, and the isolating device should eventually be upgraded to accept a lock.

Isolating only electricity and forgetting pressure, springs or gravity. Skipping the try-out because "I switched it off". One shared lock for the whole shift or a key left in the lock. Removing someone else's lock at shift handover without a defined procedure.

LOTO cards that no longer match the machine after modification. Contractors arriving with their own rules and no idea where isolation points are. No training distinguishing roles: the authorised person (performs LOTO) and the affected person (must understand what not to touch).

The emergency removal of an absent person's lock must be defined in advance: who may do it, after which contact attempts, with what machine check and how it is documented.

Energy isolation means physically disconnecting a source with an energy isolating device — main switch, disconnector, isolation valve or gate valve — that can be locked in the off position. Control circuit elements (STOP button, safety switch, light curtain, guard interlock) stop the machine but are not isolating devices for LOTO purposes.

Stored (residual) energy remains after the supply is cut: pressure in hydraulic accumulators and air receivers, compressed springs, charged capacitors, raised parts and the inertia of rotating parts. The goal is a zero energy state, confirmed by a try-out and measurement such as testing for absence of voltage.

A LOTO card, also called a machine-specific energy control procedure, describes the isolation points of one machine. The site-wide hazardous energy control programme covers the cards, training, group lockout, shift handover, emergency lock removal and periodic review of procedures.

Roles: the authorized employee performs isolation and applies the lock; the affected employee, e.g. the operator, must know the machine is locked out and what not to touch. In group lockout a coordinator manages the group lock box, and a multi-lock hasp lets several people secure the same point. Authorisation for the whole job is a separate document — the permit to work (PTW), and a site safety map helps locate isolation points.

VIMS does not replace physical locks — it brings order around them. In the Permit to Work (PTW) module, electrical and maintenance work with energy isolation has its own category: permit conditions include performing and confirming isolation, and the permit is not approved until the required points are confirmed by the responsible people.

In Registers and inspections every machine has a record where you can attach the current LOTO card and manufacturer documentation, with reminders for inspections. Training records show who holds valid LOTO training, and permits for external companies include contractor document checks.

If a near miss occurs — for example a machine moved despite a lock — the worker reports it from a phone, and root cause analysis and corrective actions (CAPA) land in one register, together with the decision to update the LOTO card.