Design Safety Standards for Equipment Operating at 600 Volts or Less

The following design safety standard requirements apply to electrical equipment operating at 600 volts nominal or less to ground.

Space Around Electrical Equipment, 600 Volts or Less

Sufficient access and working space must be provided and maintained around all electrical equipment to permit its safe operation and maintenance. This space must always be kept clear of equipment and debris. The minimum depth of clear working space at electrical equipment operating at 600 volts or less must be no less than three feet. Under certain circumstances, this measurement can be greater.

Note that where rear access is required to work on de-energized parts on the back of enclosed equipment, a minimum working space of 30 inches horizontally must be provided.

Working space around electrical equipment that is likely to require examination, adjustment, servicing, or maintenance while energized must comply with the following dimensions:

• Distances must be measured from the live parts if they are exposed, or from the enclosure front or opening if the live parts are enclosed.
• The width in front of the electrical equipment must be the greater of the width of the equipment or 30 inches.
• In all cases, the working space must permit at least a 90-degree opening of equipment doors or hinged panels.
• Other equipment associated with the electrical installation and located above or below the electrical equipment may extend no more than six inches beyond the front of the equipment.

Illumination must be provided for all working spaces around service equipment, switchboards, panelboards, and motor control centers that are installed indoors.

The working space must be clear and extend from the grade, floor, or platform to the required minimum headroom height, as follows:

• For installations built before August 13, 2007: 6.25 feet
• For installations built on or after August 13, 2007: 6.5 feet or at least the height of the electrical equipment (if it exceeds 6.5 feet in height)

Specific rules apply for equipment rated 1,200 amperes or more and over six feet wide, containing overcurrent devices, switching devices, or control devices. Refer to 29 CFR 1910.303 for information.

To learn more about Dental & Medical Hazards visit our Dental & Medical Office Course Bundle Online Training web page.