The move comes despite the fact that no strike action is taking place and all FortisBC services are operating as usual even through the contract with IBEW Local 213 expired well over a year ago.
Essential services are those the Labour Relations Board considers necessary or essential to prevent immediate and serious danger to the health, safety or welfare of residents.
"FortisBC's primary focus is on the ongoing safety of its operations and the public, while ensuring a reliable supply of natural gas to all customers," the company said in a news release Thursday.
IBEW 213 represents FortisBC employees working primarily in gas distribution and transmission, including installation and emergency response and the repair and maintenance of the gas pipeline system.
It said the company will hold discussions with its unions regarding an essential services plan.
"Until the plan is complete and approved by the Labour Relations Board, no strike action can legally occur," it said.
"Once the essential services order is received by the company, if the union wishes to continue with job action, it then has the option to issue 72-hour notice for job action," it added.
FortisBC, with 2,3000 employees, is a regulated utility providing natural gas, electricity, propane and thermal energy to 1.1 million customers in 135 B.C. communities.