Applying the code: permits, inspections and a worked installation

The earlier lessons treated the code one topic at a time: definitions, branch circuits, conductor sizing, overcurrent protection, wiring methods, devices, panelboards, grounding and special locations. On a real job they all apply at once, and the code is only one part of a process that also includes planning, permits, inspections and documentation. This final lesson follows that process from start to finish and then works through a complete small installation, a detached garage workshop fed from a house, checking every decision against the rules covered in the course.

The job from start to finish

A typical electrical installation passes through these stages:

• Scope and design: what loads, where, and what supply is available. For larger projects an engineer prepares stamped drawings; for small jobs the electrician lays out the work.
• Permit: the electrical contractor applies to the inspection authority before work starts, describing the work and paying a fee.
• Rough-in: boxes, raceways and cables are installed before walls and ceilings are closed, and a rough-in inspection is requested.
• Service connection: where a new or altered service is involved, the inspector authorizes the utility to connect.
• Finish: devices, luminaires and equipment are installed and terminated, circuits are labelled and tested.
• Final inspection and close-out: the inspector checks the completed work, and the permit is closed. Defects found are listed on a deficiency or correction notice that must be addressed.

In Canada, electrical permits are issued by the provincial or territorial inspection authority (for example, Technical Safety BC, the Electrical Safety Authority in Ontario, or the Régie du bâtiment du Québec through its own rules), or by certain municipalities with delegated authority. In most provinces only licensed electrical contractors may take out permits for others, while homeowners may be permitted to do work on their own single-family dwelling under a homeowner permit.

Inspectors do not design the installation; they verify that it complies. The responsibility for compliance stays with the installer, and the inspector may require any part of the work to be opened up or corrected.

Reading plans and specifications

On commercial work the design is communicated through drawings and specifications. Electrical drawings use standard symbols for receptacles, switches, luminaires, panels and home runs; a home run arrow with a label such as "LP-1, 5, 7" means the circuit returns to panel LP-1, circuits 5 and 7. Panel schedules list each circuit, its load and its breaker; one-line diagrams show the distribution from service to panels. The specifications state the materials and methods (for example, EMT in exposed areas, copper conductors only, minimum 12 AWG).

Where drawings and the code disagree, the code is the minimum: a design may exceed it but never fall below it. Where drawings are silent, the code still applies.

Worked installation: a detached garage workshop

A homeowner wants a detached garage converted into a workshop, 15 m from the house. The house has a 200 A, 120/240 V single-phase service with spare panel spaces. The workshop will have:

• Bench receptacles: six duplex receptacles on two 20 A circuits.
• A 240 V table saw rated 13 A at 240 V (a 3 hp motor) on its own circuit.
• A 240 V electric heater, 4 kW.
• LED lighting: about 300 W, with an exterior wall light and an exterior weatherproof receptacle.
• A future electric vehicle charger is not included now.

Step 1: Estimate the load and size the feeder

A simple estimate adds the larger loads and a reasonable allowance for receptacles. Lighting 300 W; receptacle circuits allowance 3,000 W; table saw \(240 \times 13 = 3{,}120\) W; heater 4,000 W (a continuous load).

For a 60 A feeder at 75 °C terminations, 6 AWG copper (65 A at 75 °C) is typical. The house panel must also be checked: adding about 48 A to the existing calculated load must not exceed the 200 A service (a full dwelling load calculation would be done here, using the methods introduced in Lesson 3).

Step 2: Check voltage drop

Step 3: Choose the wiring method

The feeder runs underground between the buildings. Options include direct-buried cable rated for the purpose, or conductors in rigid PVC conduit. With conduit, the conductors can be replaced or upsized later, which suits a future EV charger. Burial depth depends on the method and location (Lesson 6). Where the conduit rises out of the ground it needs protection from damage, and an expansion fitting where frost heave or temperature change could move it. Conductors in underground raceways are in a wet location, so they must be rated for wet locations (for example, RW90 or THWN-2; Lesson 10).

Step 4: Grounding and bonding at the detached building

The feeder includes an equipment bonding conductor, so the garage subpanel is treated like any subpanel: its neutral bar is isolated from the enclosure, and the bonding conductor connects to the enclosure and the equipment grounding bar. A detached building supplied by a feeder also generally needs its own grounding electrode (such as ground rods) connected to the subpanel's grounding bar, so that lightning and other surges have a local path to earth. The building also needs a disconnecting means at the point where the feeder enters (Lesson 8); the subpanel's main breaker can serve, if the panel is suitable for the purpose.

The CEC requires a grounding electrode at a separate building supplied by a feeder, with the bonding conductor run with the feeder.

Step 5: Branch circuits

Inside the workshop, the subpanel supplies:

• Two 20 A, 120 V bench receptacle circuits in 12 AWG copper, with ground-fault protection because garages and workshops are locations where it is required (Lesson 10). The exterior weatherproof receptacle also needs ground-fault protection and a weatherproof in-use cover.
• A 240 V table saw circuit sized for the motor, whose conductors must carry 125% of its full-load current: a 13 A motor needs conductors rated at least \(1.25 \times 13 = 16.25\) A, so 12 AWG, with overcurrent protection chosen for motor starting, and a disconnect within sight of the saw (the plug and receptacle may serve as the disconnect for a cord-connected tool).
• A 240 V heater circuit: \(4{,}000/240 = 16.7\) A continuous, times 1.25 = 20.8 A, so a 25 A breaker with 10 AWG copper (or as the heater's nameplate requires).
• A lighting circuit at 15 A, with switches at the entrance door and the exterior light.

Step 6: Inspection checklist

Before calling for inspection, a careful electrician checks the work against the issues inspectors most often find:

Testing and documentation

Before energizing, and as part of handing over the work, the electrician tests the installation:

• Continuity of bonding conductors and the absence of unintended neutral-to-ground connections at the subpanel.
• Insulation resistance testing of the feeder (for example, at 500 V or 1,000 V DC with a megohmmeter), looking for values in the megohms or higher.
• Polarity and correct wiring of every receptacle, using a plug-in tester, and operation of every ground-fault and arc-fault device using its test button.
• Voltage at the subpanel under load, and a check that the heater and saw run correctly.

Finally, the panel directory is completed with clear descriptions ("Bench receptacles, north wall"), and the homeowner is shown the disconnect, the test buttons and the locations of devices.

Code changes and continuing learning

The code changes with every edition, every three years, as new technology appears and incident data reveal new hazards. Recent editions have expanded ground-fault and arc-fault protection, added rules for energy storage systems, electric vehicle charging, solar installations, Power over Ethernet and DC distribution, and reorganized whole sections. A working electrician therefore keeps learning: reading the changes summary for each new edition, attending update seminars, and checking which edition and amendments the local authority enforces. Courses later in this program cover particular systems in more depth: industrial controls and motors, renewable energy, and data centre power.

The code itself states that it is a minimum standard for safety. Good work often goes beyond it: larger conduits for future cables, spare panel spaces, circuits that are clearly labelled and drawings that are kept up to date. These choices cost little at installation and make the next electrician's work safer and faster.