Condition 1:
Installations in which the wall or other equipment located directly across from the equipment being considered is insulated, with no grounded or live parts exposed. This condition is rare, so is rarely applicable.
Condition 2:
Installations in which the wall or other equipment directly across from the equipment being considered is grounded (as with equipment in a power equipment center outdoor enclosure, or with an ordinary wall across from the equipment front) or does not have exposed live parts. Concrete or masonry walls are considered as grounded surfaces. Condition two is probably the most common condition.
Condition 3:
Installations in which electrical equipment is located on both sides of the working space. Condition three is applicable for “common-aisle” installations, where two groups of equipment face each other. It would also apply in a situation where the front of one group of equipment faces the rear of a second group of equipment. Condition three requires more distance than condition two, at least in part due to the reduced working space when doors of the facing groups are open. If two groups of equipment face each other, and each has hinged doors that can open 135°, then these doors can reduce the working space available.
Disclaimer:
This article is intended for informational purposes only and is not meant to be a comprehensive summary of the requirements and specifications set forth by codes and standards. Equipment owners are solely responsible for ensuring safe working environments and compliance with regulations. Those responsible for design of facilities must comply with the clear working space requirements around equipment in the most current version of the applicable codes and standards.