Start with a written scope
Write down exactly what you want to change. “Improve the basement electrical” is too broad to price, permit, or inspect. A useful scope says which rooms are affected, how many receptacles and lights are planned, what equipment will be connected, and whether walls or ceilings will be opened. List loads by nameplate rating: a 1,500-watt heater, 7,600-watt EV charger, sump pump, freezer, or workshop tool each changes the design conversation.
Separate cosmetic device replacement from new wiring. Replacing a damaged receptacle on an existing circuit can be a limited repair, while adding a circuit, relocating concealed cable, changing a panel, or altering service conductors is a different class of work. Take photographs before demolition and sketch the proposed route so an electrician or inspector can understand what will be hidden.
Document the existing electrical system
Find the electrical panel and photograph its label, breaker sizes, service rating, and visible signs of heat or corrosion. Do not remove the dead front cover. Record which breaker turns off each room, but treat labels as unverified until you test them. Note knob-and-tube, aluminum branch wiring, cloth cable, ungrounded receptacles, water damage, or junction boxes that are inaccessible. These conditions do not automatically tell you the entire installation is unsafe, but they do justify professional assessment before additions.
- Identify the service size and available spaces in the panel.
- Check whether existing circuits are AFCI or GFCI protected where current rules require it.
- Record the cable markings, conductor material, and approximate run length only from accessible, de-energized areas.
- List future loads so the design does not need to be rebuilt next year.
Use the right planning calculations
Start with the Panel Load Calculator or Service Size Calculator when planning a major addition. Use the Wire Size Calculator for an initial conductor comparison and the Voltage Drop Calculator for long runs. These tools explain assumptions; they do not replace a permit-ready design. A load calculation must account for demand factors, continuous loads, motors, heating, EV equipment, and the actual service configuration.
Permits, inspections, and the Authority Having Jurisdiction
In Ontario, most new circuits, panel work, service changes, permanent wiring, and major renovations require an ESA notification and inspection. Rules differ across Canada, so confirm requirements with your provincial safety authority before work starts. A permit is not just paperwork: it creates a hold point where concealed work can be inspected before insulation or drywall hides conductor routing, box locations, bonding, and protection.
Plan inspection stages
- Confirm scope and permit requirements before demolition.
- Have the route, boxes, supports, protection, and rough wiring ready for the rough inspection.
- Keep junctions accessible and do not cover work before approval.
- Complete devices, covers, labels, and testing for final inspection.
Make a materials and shutdown plan
Buy listed products that match the wiring method, location, voltage, and amperage. “Same size” is not enough: devices have ratings for wet locations, tamper resistance, weather exposure, aluminum compatibility, and termination temperature. Keep a non-contact tester and a two-pole tester, but remember that a tester is only useful when used correctly on a known-live source before and after testing.
Tell household members when power will be off. Keep a flashlight outside the panel area, never work alone in a hazardous location, and do not work in wet conditions. Lock out or tag out the circuit where practical. If the breaker will not stay off, the panel is hot, or you cannot positively identify the supply, stop.
Common planning mistakes
- Beginning demolition before mapping hidden wiring, plumbing, or structural members.
- Assuming an empty breaker space means the service has capacity.
- Using a calculator result without checking conductor length, derating, terminals, and equipment instructions.
- Closing walls before inspection.
- Choosing materials based on a video or a US-only NEC example when Ontario rules apply.
When to hire a licensed professional
Use a Licensed Electrical Contractor for service and panel work, feeders, grounding and bonding, new concealed circuits, EV chargers, generators, pools, spas, wet locations, and any project requiring a permit. Hire help immediately for burning smells, buzzing, water intrusion, exposed energized parts, repeated trips, or damaged insulation. A clear scope and good photographs make the professional visit faster, safer, and more affordable.