(a) All surface transformers, unless of "dead front" construction or if installed at least eight feet above ground, shall be enclosed in a house or surrounded by a fence at least six feet high. If the enclosure is of metal, it shall be grounded effectively. The gate or door to the enclosure shall be kept locked at all times unless authorized persons are present.
(b) Underground transformers installed after August 12, 1949, shall be aircooled or nonflammable liquid cooled.
(c) Underground stations containing transformers or circuit breakers filled with inflammable oil shall be provided with door sills or their equivalent which will confine the oil if leakage or explosion occurs, and shall be of fireproof construction.
(d) Transformers shall be provided with automatic cutouts.
(e) All underground transformers or conversion equipment, whether permanent or portable, shall be kept in housings of fireproof construction; provided, that equipment designed and constructed to be fireproof is exempted from this requirement.
(f) The operator of every mine where permanent transformers or conversion equipment is installed underground shall designate or cause to be designated on the map provided for by law the locations of transformer and conversion equipment stations.
(g) "Danger - High Voltage" signs shall be posted conspicuously on all transformer enclosures, high-potential switchboards, and other high-potential installations.
Last modified: May 3, 2021