Safety Bulletin: 277v Emergency Lighting Shock Incident
What Happened:
A teammate was working inside a stairwell, pulling branch wiring for staircase lighting. While feeding the wire into a 4-square junction box, his middle finger contacted an exposed copper conductor. The conductor was energized at 277 volts. He felt a shock and observed a small spark.
Fortunately, there were no injuries—but this was a serious near miss.
The conductor was energized as part of the emergency lighting system, which had recently been turned on in an adjacent corridor. The circuit fed through the corridor and into the stairwell, but only the corridor portion had been walked and verified before energization. The stair locations were not checked prior to energizing the circuit.
At the time of the incident, Lockout/Tagout (LOTO) procedures were not in place, and the teammate did not follow zero voltage testing procedures before beginning work. The Fluke 2AC proximity tester was not used to verify zero voltage.
Why It Happened:
- The emergency lighting circuit was energized without a full walkthrough of all circuitries.
- Only the corridor circuitry was visually verified as being complete prior to energization, the stairwell where the work was occurring was missed.
- The teammate assumed the circuit was de-energized and failed to verify zero voltage.
- No zero-voltage verification was performed before contact.
What Should Have Happened:
Before starting any work in the box:
- A complete walkthrough of the entire circuit should have been conducted prior to energizing the emergency circuit.
- The teammate should have performed zero-voltage verification using a Fluke 2AC proximity tester before reaching into the box.
- If the proper zero voltage procedures had been followed the electrician would have found the energized circuit and would have stopped work and contacted the appropriate supervisor.
Moving Forward:
- Always test before you touch. If you can touch it, test it! – Fluke 2AC proximity testers are a required tool—not optional.
- Never assume a circuit is safe based on verbal direction, labels, schedules, or prior work. Test it yourself.
- When circuits are being energized, walk the entire circuit path—including all connected spaces.
- Use LOTO procedures to ensure protection when working near incomplete or in-progress circuits.
- Speak up if something doesn’t feel right. Stop and ask.
Key Reminder:
Emergency lighting circuits can be energized unexpectedly from adjacent areas. Even if the space you’re in seems isolated, shared circuits can bring power into areas that appear inactive. 277V contact can result in serious injury or fatality. This teammate was lucky—it could have gone very differently.
Let’s all take ownership of our safety and “If you can touch it, test it!”