High-voltage electrical work process map

What is in this map

14 steps across 5 swimlanes and 5 phases, with 2 decision points.

Swimlanes (who does the work)

ServiceDesk, Engineering, Authorized Person, Field Electrical & Test and Project Manager

Phases (left to right)

Request & Risk Assessment, Isolation Planning & Authorization, De-energization Verification, Work Execution & Testing and Re-energization & Documentation

Why map this process

High-voltage work is the one process on this site where a shortcut can kill someone, and the map is built to make the two life-safety gates impossible to route around on paper. The authorization decision names the Authorized Person by role, and its comment states the rule directly: a plan that person hasn't signed off does not get isolated, whatever the customer's timeline. The de-energization decision is just as blunt — proved dead with a calibrated detector, tested live immediately before and after, with the same named role signing off before anyone touches the circuit.

The map also gives 'not verified' its own loop rather than treating a failed prove-dead check as an edge case. Residual voltage after isolation usually means a mis-identified isolation point, a fed-back supply, or an undischarged capacitor bank — real, recurring causes the map's own comment names — and routing back to re-isolate and investigate is what stops someone from assuming the reading was a meter fault and proceeding anyway.

Every step in the map

This is the spreadsheet behind the diagram. The numbers in “Goes to” are row numbers, which is exactly what the editor’s “Line to” column holds — so you can read the flow here and retype any part of it.

The decision points

Every branch in the map, with the label on each outgoing line. These are the questions the process has to be able to answer.

• 4. **Authorization** granted by Authorized Person?

  Owned by Authorized Person · Isolation Planning & Authorization

  • Granted → step 6
  • Withheld → step 5

• 7. De-energization verified (**proved dead**)?

  Owned by Authorized Person · De-energization Verification

  • Verified → step 9
  • Not verified → step 8

Notes on specific steps

These notes travel with the map. In the editor they live in the Notes column and appear when you open a box.

3. Develop isolation plan: points of isolation, *LOTO* and safe working zone

Points of isolation, safe limits of approach, earthing/short-circuiting points, PPE and the boundary of the safe working zone, written down before authorization is requested, not agreed verbally at the switchboard.

4. **Authorization** granted by Authorized Person?

No exceptions for schedule pressure: Patrick Sawyer, Scanel's named Authorized Person for this job, is the only role who can grant this. A plan he has not signed off does not get isolated, whatever the customer's timeline.

7. De-energization verified (**proved dead**)?

Proved dead with a calibrated voltage detector, tested on a known live source immediately before and after. Nobody touches the circuit until this reads confirmed dead, isolated, and Patrick Sawyer has signed off.

8. Re-isolate and investigate *residual voltage*

Residual voltage here usually means a mis-identified point of isolation, a fed-back supply, or a capacitor bank that has not discharged. Re-isolate at the correct point and re-run the prove-dead check; do not proceed on the assumption the reading was a meter fault.

12. Complete high-voltage work documentation and permit close-out

Permit-to-work record, the signed isolation/authorization trail, de-energization proof, test results and the re-energization sign-off filed together, the set an auditor or the customer's own HV authority will ask for.

Making it yours

The five phases (Request & Risk Assessment, Isolation Planning & Authorization, De-energization Verification, Work Execution & Testing, Re-energization & Documentation) run in Horizontal lane; the five roles, including Authorized Person as its own lane rather than folded into Engineering, run in Vertical lane. When adapting this for your own operation, keep Authorized Person as a distinct swimlane even if today it's one person wearing two hats — the lane is what makes the authorization decision's owner visible on the diagram, not just in a policy document.

What to watch out for

• Don't merge the isolation-planning row with the authorization decision. The plan (points of isolation, LOTO, safe working zone, written down) and the decision to authorize it are two different acts at two different moments in time, and a customer's HV authority reviewing your records later will look for both, separately.
• The prove-dead check has to happen after isolation, as its own gate, not as an assumption baked into the isolation step. The map's comment is explicit that nobody touches the circuit until this reads confirmed dead — don't fold it into 'isolate and lock out' just because they usually happen minutes apart.
• Keep the documentation row's contents as a set, not a single 'paperwork done' checkbox: the permit-to-work record, the signed isolation/authorization trail, de-energization proof, test results and the re-energization sign-off are named separately because an auditor or the customer's own HV authority asks for that exact set.

Frequently asked questions