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How to identify Unknown Circuits

  • Updated

Unknown Circuits can include mislabeled or unmarked circuit breakers in a Panel, and outlets in a home that correspond to an unknown circuit breaker. Below is a guide to help identify Circuit breakers with the loads that they're connected to in a home.

Common breaker sizes and their corresponding loads:

Starting at the panel, notice the breaker rating and how many slots in a panel the breaker takes up. Typical installs of circuit breakers in a residential home are:

  • 15A or 20A single pole - lights, outlets, small gas appliances, and range hoods.
  • 15A or 20A 2-pole - combined kitchen outlets (e.g. disposal + dishwasher), small pumps and fans.
  • 30A 2-pole - laundry equipment, electric water heaters.
  • > 40A 2-pole - range/oven, HVAC, EV Charger.

Using the SPAN Home App:

The SPAN Home App can also provide insight into what types of loads are in a Circuit. Occasionally, some breakers are installed in a Panel as spares - not wired to anything. In the SPAN Home App, look at the 'Energy Use over Time' over the day/week/month of an Unknown Circuit. Some common energy (kWh) profiles to loads are:

  • Consistent - lights, outlets containing electronic equipment (e.g. TV, computers, networking equipment), fridges.
  • Regularly On-Off - smart lights, water heaters, HVAC, pumps, EV Charger.
  • Irregularly On-Off - kitchen appliances, laundry washroom ventilation fans, convenience outlets (e.g. phone chargers, hairdryer, vacuum, garage and shed outlets).
  • Zero - Spare* or space. Check the load profile over a year to ensure nothing is connected.
    * If you’d prefer to have a spare Circuit removed from your app, please contact SPAN Support. 

Tracing an outlet back to its circuit breaker:

Depending on the age of the home and how many renovations it went through, it is often not obvious which circuit breaker is wired to a specific outlet in a home. To identify the circuit breaker responsible for certain outlets in a home, try the following:

  • Plug a small lamp or audio device into the outlet and use the SPAN Home App to turn on/off circuits. Note at which Circuit toggle that the device turns on and off.
  • Use a Digital Circuit Breaker Finder, available at general hardware stores.

If you are still unsure, please contact your installer or local electrician for additional guidance.