§6.3 — Live Working (WOS)

Live working (Dutch: Werken Onder Spanning, WOS) is any action on or with live parts without first de-energizing the installation via the five LOTO steps (see de-energized working). It is explicitly the exception, not an equivalent alternative: NEN-EN 50110-1 and NEN 3140 set de-energized working as the default, and allow live working only when that is demonstrably not feasible.

When is live working allowed?

Live working is only permitted when de-energizing is not reasonably possible. Recognized reasons:

1. Continuous process — a production line, hospital supply, or refrigeration installation where switching off itself causes unacceptable damage or danger (e.g. loss of an operating theatre supply).
2. De-energizing itself creates a greater risk — for example switching off emergency lighting or a fire alarm panel during a fault elsewhere in the building.
3. Diagnosis requires voltage — some measurements (e.g. tracing an intermittent fault) cannot be performed without voltage; the measurement itself is then the only live-working action, followed by a de-energized repair.

Not valid reasons: time pressure, a customer not wanting production to stop, "not wanting to fetch an earthing set," or habit. These are common exam traps — the standard only accepts technical or safety reasons, never convenience or scheduling.

Who may perform live working?

• Only a Competent Person (VP) with a separate, specific WOS appointment — a regular VP appointment does not automatically grant this right. Live working requires additional training in the specific risks, adapted tools and PPE.
• Never an Instructed Person (VOP). A VOP works only under supervision on de-energized installations, for the specifically assigned task.
• A second person must always be present, instructed in emergency procedures (emergency shutdown, first aid, raising the alarm) and able to intervene without becoming a victim themselves.

Mandatory work permit

Every live-working action requires a written work permit, containing at minimum:

• The reason why de-energizing is not possible.
• The technical and organizational measures taken.
• The names of the executing VP and the second person.
• The validity period of the permit (never "until the work is finished" without a time limit).
• The agreed emergency procedure and means of communication.

The Work Responsible Person (WV) issues this permit and remains ultimately responsible for its conditions.

Tools and PPE

Live working requires equipment that goes beyond standard de-energized work:

Tools and PPE are visually checked for damage before every use — a small crack in the insulation of a screwdriver or glove makes it unfit for use, regardless of remaining test validity.

Procedure — five steps for live working

Unlike the fixed five-step rule for de-energized work, live working has no standardized step sequence, but does follow a fixed preparation logic:

1. Draw up a work permit and task risk assessment — specific to this live-working task, not a generic permit.
2. Check PPE and tools — visually and functionally, immediately before starting.
3. Cordon off the work zone — shield adjacent live parts so the approach zone is not unintentionally breached.
4. Perform the work with the second person present — using a pre-agreed stop word or signal for an emergency stop.
5. Close out and evaluate — check PPE and tools for damage afterwards, close the work permit, and report any deviations to the WV.

If something goes wrong

The second person must be able to intervene immediately: de-energize the installation via the main switch, or push the victim away with a dry, non-conductive object if switching off is not immediately possible. See arc flash — what to do in an electrical accident for the follow-up steps (emergency call, CPR/AED, medical check, mandatory reporting).

Common exam mistakes

1. Confusing live working with "working in the vicinity" — that is a separate, third work category (see danger zone and approach zone), with different requirements than working directly on a live part.
2. Assuming every VP appointment permits live working. Without a specific WOS appointment, a VP is not authorized for this, even though they may independently perform de-energized work.
3. Live working without a second person "because it's just a small action" — this is never allowed, regardless of duration or apparent simplicity.
4. Treating time pressure or a customer's wish as a valid reason for live working — this does not meet the "not reasonably possible" criterion.

Further reading

• De-energized working — the 5 steps (LOTO)
• Danger zone and approach zone
• Arc flash — risk, energy and PPE
• PPE overview
• NEN-EN 50110-1:2023