Shock and Arc Flash Protection
Electrical equipment such as switchboards, panelboards, industrial control panels, meter socket enclosures and motor control centers that are installed in other than dwelling units are likely to require examination, adjustment, servicing or maintenance while energized shall be field marked to warn persons of potential electric shock and arc flash hazards.
The marking referred to in Subrule (1) shall be located so that it is clearly visible to persons before examination, adjustment, servicing or maintenance of the equipment.
This article is from the 2009 Canadian Electrical Code – Part 1, section 2-306 (1) and (2)
Canadian Standards Association – www.csa.ca