My wife works for an insurance organization and is not self-employed as she receives a T4 and is based in Saskatchewan; however, she works from home - not at her employer's office. Is she eligible to claim any deductions and expenses (power, energy, water, property tax, insurance, etc.) despite not being self-employed yet still works from home? Does this depend on square footage her office workspace takes up? Her employer only pays for the phone and Internet bill.
If your wife receives a T2200 - Declaration of Conditions of Employment from her employer that states she performs more than 50% of her duties at home, she can claim "Workspace in the Home Expenses". The type of expenses which can be claimed differ between Salaried and Commission employees.
This CRA guide explains in detail which expenses can be claimed: https://www.canada.ca/en/revenue-agency/services/forms-publications/publications/t4044/employment-expenses-2016.html#P267_17648