Just because a circuit has been isolated and locked out doesn’t mean you can’t be electrocuted, as one of our Tasmanian apprentices found out recently.
While the electrical shock was a minor one, it’s a scary reminder of just how easy you can be injured or killed at work.
A 3rd year apprentice was asked to replace a fluro light. The circuit was isolated, locked out and tested (using a multi-meter and volt stick) to ensure it was de-energised. He proceeded to remove the fitting, cutting the active and neutral conductors, when it was discovered on the neutral conductors became live when disconnected.
This installation involved a ‘crossed circuit’, where neutrals of different circuits were interconnected, meaning that a neutral conductor which was disconnected from another (isolated) circuit became live.
How to avoid this?
You never know for sure how someone has wired a circuit prior to you working on it. Always be vigilant and conduct the appropriate tests prior to commencing work.
- Always test after conductors have been cut or disconnected, particularly neutrals.
- Always test between Active and Earth, Neutral and Earth, Active and Neutral
- By wearing proper PPE and using electrically suitable equipment (i.e. Fiberglass ladders) we may minimize the impact of such instances
Last year an electrical apprentice died in Victoria due to sustaining a shock from similar issues regarding a live neutral conductor.
AS/NZS 4836:2011 Safe working on low-voltage electrical installations
This standard is mandatory when working on electrical equipment.
3.5(C) (viii) Particular care should be taken when removing neutral connections because tests may have indicated a de-energised situation. However, when these connections are removed, a voltage may be present between conductors or between conductors and earth.