Rule 26-008 Sprinklered Equipment (see Appendix B)
Where electrical equipment vaults or electrical equipment rooms are sprinklered, the electrical equipment contained in such vaults or rooms shall be protected where needed by noncombustible hoods or shields so arranged as to minimize interference with the sprinkler protection.
Rationale for Rule 26-008.
This Rule is intended to protect electrical equipment located within a ventilated enclosure from direct spray from a sprinkler head.
Intent for Rule 26-008 (see Figures 26-008(a) and (b)).
Some parts of buildings are sprinklered. Thus, it is possible that an electrical equipment vault or an electrical equipment room might have to be sprinklered. While the sprinkler heads are there to ensure that any fire in that room will not spread to other parts of the building, we do not want any water from an operating sprinkler head to get into the electrical equipment and cause further problems.
As noted in Appendix B, the intent of the Rule can be met through the use of weatherproof equipment. The intent of the Rule is also met when water following a direct line-of-sight path from the sprinkler head cannot strike live parts within the enclosure through ventilation openings in sides and tops of electrical equipment and when water accumulating on the top of the equipment cannot flow into the interior through significant openings. Examples of significant openings are ventilation openings, openings around bus ducts, and dry-type armoured cable connectors. Bolts and seams do not present significant openings.
In all other cases, we intend that noncombustible hoods or shields be provided over the equipment.
Protective Shields Over Equipment
Protective Shields for Electrical Equipment