Home > For Business > Electrical Safety > Vault Owner Resources

Vault Owner Resources

Customers who own the transformer vault located in their buildings are responsible for the inspection and maintenance of their vault.

Toronto Hydro-Electric System Limited’s (“Toronto Hydro”) Conditions of Service, which apply to everyone who receives electricity from Toronto Hydro, state in part that:

1.7.6    Repairs of Customer’s Physical Structures

The Customer is responsible for providing, maintaining, repairing and replacing, in a safe condition satisfactory to Toronto Hydro, all the Customer’s civil infrastructure on private property or in the public road allowance for non-metered connections, including but not limited to poles, underground conduits, cable chambers, cable pull rooms, transformer rooms, transformer vaults, transformer pads, tap boxes, handwells, and junction boxes that Toronto Hydro deems required to house Toronto Hydro’s Connection Assets.

The Customer shall inspect its facilities at regular intervals, including those facilities that house exposed high voltage equipment that are owned by Toronto Hydro…

For a complete set of the Conditions of Service please review Toronto Hydro's Conditions of Service. In particular, vault owners may be interested in Sections 1.7.1, 1.7.2, 1.7.4, 1.7.6, 2.3.7,,,, 3.2, 3.2.1, 3.2.2, 3.3, 3.3.1, 3.3.2, 3.4, 3.4.1 and 3.4.2.

In the interests of public safety, Toronto Hydro has placed a lock on the transformer vault doors so that only qualified Toronto Hydro personnel have access to these rooms and the high voltage electrical equipment they contain.

When a vault owner requires access to his or her transformer vault for on-going general maintenance and inspection, Toronto Hydro must be contacted to arrange for access at 416-542-3476. 

Examples of when vault access would be required:

1 ) a vault owner requires access to inspect the general condition of his or her transformer vault; or

2) during the vault owner’s previous vault inspection, the vault owner noted that he or she is required to perform repair or maintenance work to his or her transformer vault.

Also, if during a routine Toronto Hydro inspection of its equipment inside a transformer vault, the crew finds a situation where maintenance work needs to be performed on the vault structure or access door, the Toronto Hydro crew may leave a Customer Advice Form (CAF) with the vault owner or his agent, such as a superintendant, noting the deficiencies that require the vault owner to follow up. Upon receipt of the CAF, the vault owner must contact Toronto Hydro to obtain access to the vault to perform any necessary repairs.

Toronto Hydro will provide transformer vault entry once per year, per vault location at no charge to the vault owner. If further entry into the transformer vault and/or an isolation of the electrical equipment inside the vault is required, only the costs incurred by Toronto Hydro in accommodating the vault owner’s request will be charged to the vault owner.