Heated Stairs Give Electric Shock

Location: Lake Cowichan

Regulated industry sector: Electrical – Low voltage electrical system (30V to 750V) 

Incident overview

A heat trace circuit shorting out to concrete steps on a school staircase was permanently disconnected after giving a teacher an electric shock. The steps were observed by a student to be vibrating. When the teacher touched it to investigate, they received an electric shock.

Trace heaters, or heat trace, are used to prevent surfaces from freezing. Investigation found that the deteriorated insulation on circuit conductors caused a short circuit in the concrete. Ground fault circuit interrupter (GFCI) protection was not required at the time of installation, but upgrading to this type of protection may prevent similar incidents from happening.