Many electrical distribution systems contain vaults and equipment rooms with insufficient maintenance access and working clearances that may not comply with current codes and OSHA regulations. Such installations may be considered to be "grandfathered" by code officials, leaving the maintenance staff no choice but to live with them until equipment failure or system expansion provide a driver for an upgrade project. Older systems are often 2,400V or 4,160V, and as facilities grow it may be necessary to upgrade the system to a higher voltage to accommodate load growth without increasing the number or size of feeders. However, the larger dimensions of higher voltage ratings of standard switchgear may preclude this option when space is tight.
Figure 1 shows a lineup of six compact switches rated 15kV, 600A, installed in the 13,800V distribution system of a high-rise office building. This equipment uses about half of the floor space that would be required for traditional air insulated switchgear serving the same function. While this particular product is similar in appearance to, but smaller in scale than traditional switchgear, other designs are available that minimize vertical height, are fully weatherproof, or have other features that may be advantageous for a particular project.