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 construction.
- Total enclosure with 4-hour fire resistive construction
- Class "A" opening protective
- All penetrations sealed with tested assembled 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 indicating: "High Voltage"
- Signage shall be provided on the entry doors indicating: "Authorized personnel only", "Emergency phone numbers"
- Access shall be regulated by the utility company
- 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.