Office Policy: Fire Protection of Transformer Vaults
To: ALL FIRE
From: Fire Marshal M. M. Stone
Date: October 2, 1997
Recent developments in various construction projects have
raised concerns of fire protection in main electrical service
transformer vaults. The following will be considered as Office
Policy for all projects permitted after this date.
This office recommends the installation of
service main electrical transformers be located outside the
footprint of the building they serve.
When service main electric
transformer vaults are located within the footprint of the
building, the following design criteria shall be used for vault
Total enclosure with 4-hour fire resistive
Class "A" opening protective
All penetrations sealed with tested assemble
for that use
Fire detection equipment tied to the
buildings fire alarm system
Transformers shall be the only equipment
permitted within the vault area
Signage shall be provided on the exterior of
walls indicated "High Voltage"
Signage shall be provided on the entry doors
"Authorized personnel only"
"Emergency phone numbers"
Access shall be regulated by the utility
Sprinkler heads shall be deleted from the
vault area as with the above listed requirements the vault area
can be classified as outside of the building.
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