Open Neutral Wire Hazards
An open neutral is the most dangerous and unknown hazard a worker can encounter when it's line is not de-energized.
Open or Loaded Neutral
It's important to understand that in a 3-phase electrical system, all three phases must be verified as de-energized or there may be the potential for a shock. The neutral circuit wire (usually white) is grounded, but is under a load and the source of the neutral current cannot always be identified.
If a grounded (neutral) service conductor which serves as the effective ground-fault current path is opened, a ground fault cannot be cleared and the metal parts of electrical equipment, as well as metal piping and structure steel will become and remain energized providing the potential for electric shock.
Potential hazards include:
- Breaking a neutral under load can create a shock hazard.
- Workers contacting a lifted neutral potentially provide an alternative path to ground.
- A broken neutral or lifted neutral can result in a shock or an arc.
For instance, in 2005 a worker received a shock after lifting a neutral from its bus bar. The neutral received its power through an emergency light that received power from another distribution panel.
Knowledge Check Choose the best answer for the question.
9-7. If you see a loose white wire on an energized circuit, what does it mean?
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