Reference

Electrical glossary

127 terms from the panel, the code book and the permit, in plain language.

120/208 V: A three-phase, four-wire system common in apartment towers, condos and smaller commercial buildings. A connection from any phase to neutral feeds lighting and receptacles, and a connection between two phases feeds larger equipment such as ranges, heaters and EV chargers. → →
120/240 V: The single-phase, three-wire supply to most detached houses. Ordinary receptacles and lights use one line and the neutral, while dryers, ranges, EV chargers and heat pumps use both lines. →
347/600 V: A three-phase distribution voltage used in larger commercial and industrial buildings in Canada. The higher voltage serves motors and large equipment, the line-to-neutral voltage serves high-output lighting, and step-down transformers supply the building’s receptacles. → →
AEUC (Alberta Electrical Utility Code): The Alberta code that governs electric utility systems, such as distribution lines, transformers and the utility side of a service, as distinct from the Canadian Electrical Code that governs wiring inside a customer’s premises. → →
AFCI (arc-fault circuit interrupter): A breaker or device that watches the current waveform for the signature of arcing, such as a loose connection or a damaged cable, and opens the circuit before the arcing can start a fire. → →
Alberta Utilities Commission (AUC): The provincial regulator that approves utility tariffs, including ENMAX Power’s distribution rates, and sets the rules for connecting micro-generation to the grid. → →
Aluminum wiring: Branch-circuit wiring made with aluminum conductors instead of copper, found in some homes built in a limited era. Its connections need devices and methods rated for aluminum, because unsuitable terminations can loosen and overheat. → →
Ampacity: The current a conductor can carry continuously without exceeding its temperature rating, which depends on its size, material, insulation and installation conditions. Breakers are sized to protect it. → →
Ampere (amp): The unit of electric current. A service, panel or breaker rating in amps describes how much current it is built to carry or interrupt safely. →
Annual electrical permit: A City of Calgary permit that covers ongoing electrical maintenance and minor work at one facility for a year, instead of a separate permit for each job, typically where a qualified electrician is on staff or under contract. → →
Apprentice electrician: A registered learner in Alberta’s electrician trade who combines on-the-job hours with classroom periods and works under the supervision of a certified journeyperson. →
Arc flash: A sudden release of heat, light and pressure when current jumps through the air between conductors, usually during work on energized equipment. Commercial sites assess arc flash hazards and label equipment so workers wear the right protection. →
Automatic transfer switch (ATS): A switch that senses a utility outage, starts or accepts a standby source such as a generator, and transfers selected loads to it, then transfers back when utility power returns, without ever connecting the two sources together. → →
Ballast: The device that starts and regulates current in fluorescent and HID lamps. LED retrofits often remove or bypass it, which changes how the fixture is wired and labelled. →
Battery energy storage system: A battery, inverter and controls that store electricity for later use, often paired with solar or used for backup. In Calgary it needs a contractor permit; it is excluded from homeowner permits. → →
Bi-directional meter: A utility meter that records energy flowing in both directions, from the grid to the site and from the site to the grid, so a micro-generator can be credited for what it exports. →
Block heater: An electric element that keeps a vehicle engine warm in cold weather. In Calgary, block heaters plugged into outdoor or garage receptacles are a common cause of winter overloads and GFCI trips. → →
Bonding: Connecting metal parts that are not meant to carry current, such as boxes, enclosures, piping and hot tub frames, so they stay at the same potential and a fault clears quickly instead of leaving touchable metal energized. → →
Branch circuit: The wiring from the final breaker or fuse in a panel out to the receptacles, lights or equipment it serves. → →
Bus bar: A solid conductor inside a panel or switchgear that distributes power to the breakers attached to it. Breakers clip or bolt onto the bus. → →
Busway: Enclosed, prefabricated bus bars run through a building, with plug-in points along their length, used to distribute large amounts of power flexibly in data halls, plants and risers. → →
Cable tray: An open support system, like a ladder or trough, that carries many cables through ceilings and plants where conduit would be impractical. →
Calculated load: The demand an electrician works out, using the method the code sets, to size a service or feeder. It is not the sum of every nameplate, because the code accounts for loads not all running at once. → →
Canadian Electrical Code (CE Code): The national installation standard for electrical work, published by CSA Group as CSA C22.1 and adopted in Alberta under the Safety Codes Act. New editions take effect in Alberta automatically, with transition rules tied to the permit date. →
Carbon monoxide (CO) alarm: An alarm that detects carbon monoxide from fuel-burning appliances or an attached garage. Building codes set where CO alarms are required in homes with those sources. →
Circuit breaker: A switch that opens automatically when current exceeds what the circuit’s wire can carry, or when a short circuit occurs, and can be reset once the cause is fixed. → →
Combination-type AFCI: An arc-fault breaker designed to detect both series arcing, such as a loose connection, and parallel arcing, such as a crushed cable, on a branch circuit. →
Compulsory certification trade: A trade in Alberta where only registered apprentices, certified journeypersons or holders of a recognized certificate may perform the trade’s work. Electrician is one. →
Concealed wiring: Wiring hidden behind drywall, ceilings or finishes. In Calgary, concealed wiring installed without a permit cannot be legalized under a homeowner permit; a contractor must take it on, and walls may need opening for inspection. → →
Conduit: A rigid or flexible tube, metal or plastic, that protects conductors and lets them be pulled in, replaced or added later. It is common in commercial work, underground runs and exposed locations. → →
Construction value: For a Calgary trade permit, the total value of labour and materials for the job, including materials the customer supplies. The contractor permit fee is calculated from it. →
Contractor permit (trade permit): An electrical permit taken out by an electrical contractor, through a master electrician, for work at a customer’s property. It is required for everything a homeowner permit excludes. → →
CT metering (current transformer metering): Metering for larger services in which current transformers around the service conductors feed a scaled-down signal to the meter, instead of the full current passing through a socket meter. ENMAX requires it above a set service size. → →
Customer contribution: The part of a utility’s cost to build or change a service connection that the customer pays, after the utility’s own investment toward new load is deducted. → →
DC fast charging: EV charging that supplies direct current straight to the vehicle battery at high power, bypassing the car’s onboard charger. It needs a large three-phase supply and is used at public sites and fleet depots, not homes. →
Dedicated circuit: A branch circuit that serves a single appliance or piece of equipment, such as an EV charger, furnace, microwave or hot tub, so no other load shares it. → →
Disconnect switch: A switch, often lockable, that isolates a piece of equipment such as a hot tub, heat pump or motor so it can be serviced safely. → →
Distribution tariff: The regulated charges and terms a wire owner such as ENMAX Power applies for delivering electricity over its lines, approved by the Alberta Utilities Commission and billed regardless of which retailer a customer chooses. →
Double tap: Two conductors under a breaker terminal designed for one. It is a common inspection finding and usually means the panel has run out of spaces. → →
Electrical contractor: A business that performs electrical work for customers. In Calgary it needs a master electrician to obtain permits, a City business licence and City qualified-trade registration. →
Emergency lighting: Battery units or generator-backed fixtures that light exit routes when normal power fails, required in many commercial and multi-unit buildings and tested on a schedule. → →
Energization: The utility connecting power to a new or altered service. In Calgary, ENMAX energizes a site only after the electrical inspection authority has approved it, and requests go through the customer’s retailer. →
ENMAX Power: The regulated distribution utility that owns and operates the wires in Calgary, from substations to the service connection at each building, separate from the retailer that sells the energy. → →
EVEMS (EV energy management system): A device that monitors a home or building’s load and reduces or pauses EV charging when other demand is high, so a charger can be added without exceeding the service or feeder capacity. → →
EVSE (electric vehicle supply equipment): The charging station itself: the wall unit, cable and connector that safely deliver power from a circuit to an electric vehicle. → →
Feeder: The conductors that carry power from a main panel or switchboard to a subpanel or distribution point, rather than directly to end loads. → →
Final inspection: The last inspection on a permit, done when devices and fixtures are installed and no live wiring is exposed. The permit closes when the inspector accepts it. → →
Fire alarm system: The detectors, pull stations, panel and signalling devices that warn occupants of fire in larger buildings. In Calgary, installing or altering one needs both an electrical and a building permit, and the system must be verified. → →
Fuse: A one-time protective device whose metal link melts when current exceeds its rating. A fuse larger than the wire’s rating defeats its purpose. → →
Gang meter base: A single meter assembly that serves several rowhouse or townhouse units from one shared service. Adding large loads to one unit affects the capacity available to all of them. → →
Generator interlock: A mechanical device on a panel that prevents the main breaker and a generator inlet breaker from being on at the same time, so a portable generator cannot back-feed the utility lines. →
GFCI (ground-fault circuit interrupter): A receptacle or breaker that compares the current leaving on the hot conductor with the current returning on the neutral and cuts power when some is leaking to ground, such as through water or a person. → →
Ground fault: Current flowing from a live conductor to ground by an unintended path, such as through water, a damaged insulation layer or a person. GFCIs are designed to detect it. → →
Grounding: Connecting the electrical system to the earth, through a grounding electrode and conductor, to stabilize voltage and give lightning and surges a path. It works together with bonding. → →
Grounding electrode: The rod, plate, foundation steel or other conductor in contact with the earth to which a building’s electrical system is connected. →
Heat pump: Equipment that moves heat into or out of a building using a refrigerant cycle and an electric compressor. An all-electric heat pump is often the load that pushes a house toward a service upgrade. → →
Heat trace: Electric heating cable run along pipes, roof edges or drains to stop freezing. It needs the right circuit protection and is a common winter load in Calgary. →
High-bay lighting: Fixtures designed for tall ceilings in warehouses, gyms and plants, now mostly LED with occupancy and daylight controls. →
Homeowner permit: A City of Calgary electrical permit issued to an owner who lives in the home and does the work personally. It excludes rentals, apartment-style condos, and work such as the service, panel, solar, batteries and EV wiring. →
Hot tub disconnect: A switch, usually GFCI-protected, mounted within sight of a hot tub so power can be cut for service. Every hot tub must ultimately be GFCI-protected. → →
Hydrovac: Excavation that uses pressurized water to loosen soil and a vacuum to remove it, used to expose buried lines without striking them with a blade or bucket. →
Insulation resistance test: A test that applies a controlled voltage to a de-energized cable and measures leakage through its insulation, used to find damaged wiring behind walls. → →
Inverter: Equipment that converts direct current from solar panels or batteries into alternating current matching the grid. Utility-connected inverters must meet certification standards the utility specifies. → →
Journeyperson electrician: A tradesperson who has completed the electrician apprenticeship and holds an Alberta trade certificate, allowing them to perform and supervise the trade’s work. →
Kilovolt-ampere (kVA): A unit of apparent power used to rate transformers, generators and commercial services. It reflects both the real power used and the reactive power circulating in the system. →
Kilowatt (kW): A unit of power: the rate at which an appliance uses energy, or a solar array produces it, at a given moment. → →
Kilowatt-hour (kWh): A unit of energy: power multiplied by time. Electricity bills charge for energy in kilowatt-hours. → →
Knob-and-tube wiring: An early wiring method using single insulated conductors run on ceramic knobs and through ceramic tubes, with no ground conductor. Insurers often ask about it in very old homes. → →
Level 1 charging: Charging an electric vehicle from an ordinary household receptacle with the cord supplied with the car. It is slow but needs no new circuit. → →
Level 2 charging: Charging from a wall-mounted charger on a dedicated higher-voltage circuit, the kind that also feeds a dryer or range. It is the usual home and workplace charging setup and needs a permit in Calgary. → →
Load calculation: The code method for working out a building’s calculated demand to decide whether a service or feeder is large enough. In Calgary it must be done by a qualified electrician or engineer, not under a homeowner permit. → →
Load centre: The residential panel that holds the main breaker and branch-circuit breakers, often just called the panel or breaker box. →
Load management: Controls that shed or delay certain loads when total demand approaches a limit, so new equipment can share existing capacity. EVEMS is one form. → →
Locate: The marking of buried utility lines by their owners, on request, before ground disturbance. In Alberta, requests go through Utility Safety Partners. →
Main breaker: The breaker that disconnects and protects the whole panel. Its rating usually indicates the service size, and replacing it is excluded from Calgary homeowner permits. → →
Master electrician: A certificate issued by Alberta’s Safety Codes Council to an experienced certified electrician who passes a code exam. Master electricians are the only contractors who can obtain electrical permits in Alberta. → →
Meter base (meter socket): The enclosure on the outside of a building that holds the utility meter and connects the service conductors to the building wiring. The customer supplies and owns it; the utility owns the meter. → →
Micro-generation: Small-scale renewable or alternative generation, such as rooftop solar, installed at a customer’s site mainly to meet its own consumption and connected to the grid under Alberta’s Micro-Generation Regulation. → →
Net billing: A way of settling a micro-generator’s account in which energy exported to the grid is credited and energy imported is charged. In Alberta, small micro-generators are credited at their retail energy rate unless agreed otherwise, and delivery charges are not reduced. →
Neutral: The conductor that carries current back to the source in a normal circuit. It is grounded at the service but is a separate conductor from the equipment grounding conductor. → →
Occupancy sensor: A control that switches or dims lights based on whether a space is occupied, a standard part of commercial lighting retrofits and energy code compliance. →
Overload: More current on a circuit than its wire is rated for, usually from too many loads at once. A breaker’s thermal element trips on it after a delay. →
Pad-mounted transformer: A ground-level, locked utility transformer, usually green, that steps distribution voltage down for buildings served underground. → →
Panelboard: A commercial panel that distributes power to branch circuits or feeders, installed in electrical rooms and fed from switchboards or transformers. → →
Permit (electrical): Authorization under Alberta’s Safety Codes Act to install, alter or add to an electrical system, followed by inspections. In Calgary it is issued by the City. → →
Photovoltaic (PV) system: Solar panels, wiring, disconnects and an inverter that turn sunlight into electricity. In Calgary it needs an electrical permit and a licensed contractor. → →
Pot light (recessed light): A light fixture set into the ceiling so it sits flush with the surface. Adding pot lights means new boxes and wiring, which needs a permit. → →
Power factor: The ratio of real power used to apparent power supplied. A low power factor, common with motor loads, means more current for the same work, which affects equipment sizing and some utility charges. → →
Private locator: A company hired to find customer-owned buried lines, such as garage feeds, irrigation and private gas lines, which utility locate requests do not cover. →
Rate of Last Resort: Alberta’s default electricity energy rate for customers who have not signed a retailer contract, which replaced the Regulated Rate Option. It covers energy only, not delivery charges. →
Re-inspection: A return visit by the City inspector after work was found not acceptable, charged as a separate fee in Calgary. → →
Receptacle: The code term for an outlet you plug into. Receptacle type, rating and protection depend on where it is and what it serves. → →
Red Seal: An interprovincial standard of excellence endorsement for certified tradespeople. In Alberta the Red Seal construction electrician trade carries the provincial title Electrician. →
Retailer (electricity retailer): The company that sells electricity to a customer and bills for it. In Calgary it is separate from ENMAX Power, which owns the wires, and energization requests go through it. →
Rough-in: The stage when boxes are mounted and cable is run but walls and ceilings are still open. The rough-in inspection happens before anything is covered. → →
Safety Codes Act: The Alberta law that adopts the electrical, building and other codes, requires permits for regulated work, and sets penalties for working without one. → →
Safety Codes Council: The Alberta body that certifies master electricians and safety codes officers and collects a levy on each permit, which appears as a separate line on Calgary permit fees. → →
Secondary suite: A self-contained second dwelling within a house, such as a basement suite. Its electrical work needs permits, and Calgary asks for a load calculation sheet to confirm the service can carry it. → →
Service (electrical service): The equipment that brings utility power into a building: the service conductors, meter base, main disconnect and panel. Its ampere rating sets how much the building can draw. → →
Service drop: The overhead utility conductors that run from a pole to the attachment point on a building. Underground services use a buried service lateral instead. →
Service entrance conductors: The customer-side conductors between the utility connection point and the main disconnect. Because nothing upstream on the customer side protects them, Alberta limits their length inside a building. →
Service mast: The rigid pipe on the outside of a house that raises the overhead service conductors to a safe height and carries them down to the meter base. → →
Service upgrade: Replacing a building’s service with a larger one, often with a new panel, meter base and mast, coordinated between an electrical contractor and ENMAX Power. → →
Short circuit: A low-resistance fault between conductors that drives a very high current. A breaker’s magnetic element trips on it almost instantly. →
Single-phase: A supply with one alternating voltage waveform, used by nearly all houses. Larger buildings and motors usually need three-phase power. →
Smoke alarm (interconnected): A hard-wired smoke alarm linked to the others in a home so all sound when one detects smoke. Building codes require interconnection where multiple alarms are needed. →
Split-bus panel: An older panel design with no single main breaker, where several breakers together disconnect the house. It usually means an electrician should assess capacity before loads are added. → →
Stab-Lok: A breaker and panel design sold under the Federal Pioneer name in Canada and by Federal Pacific Electric in the United States. It is common in older Calgary homes and often asked about by insurers. →
STANDATA: Alberta’s official code bulletins, interpretations and variances that explain how the province applies the Canadian Electrical Code and other codes. →
Standby generator: A permanently installed generator, usually natural-gas fired, that starts automatically in an outage and feeds selected loads through a transfer switch. → →
Subpanel: A secondary panel fed from the main panel, used to add circuits in a garage, shop, suite or addition without running every circuit back to the main. →
Surge protective device: A device at the panel or receptacle that diverts brief voltage spikes, from lightning or switching, away from connected equipment. → →
Switchgear: Large assemblies of breakers, switches, metering and bus that receive a commercial or industrial service and distribute it to feeders, sized and coordinated by an engineer. → →
Tamper-resistant receptacle: A receptacle with internal shutters that open only when both prongs of a plug enter together, preventing children from inserting objects. →
Tandem breaker: A breaker that fits two circuits into one panel space. Panels accept them only in specific positions, and extra tandems are often a sign the panel is full. → →
Temporary service (construction power): A short-term service that powers a construction site before the permanent service is energized. In Calgary it needs a fused disconnect ahead of the meter. → →
Tenant improvement: Fit-out work that adapts a commercial space for a tenant, including lighting, power and data. Calgary issues tenant-space electrical permits separately from base building permits. →
Thermography (infrared scanning): Using a thermal camera to find hot connections, overloaded conductors and failing components in energized equipment before they fail. →
Three-phase: A supply with three alternating voltages offset in time, which delivers power more smoothly and efficiently than single-phase and runs large motors and commercial buildings. → →
Transformer: Equipment that changes voltage from one level to another. Utilities use them to step distribution voltage down for customers, and buildings use them internally to derive lower voltages. → →
UPS (uninterruptible power supply): Battery-backed equipment that keeps critical loads running without interruption through an outage or disturbance, bridging the gap until a generator takes over. →
Utility Safety Partners: Alberta’s notification centre for buried utilities, formerly Alberta One-Call. Requests to have lines located before digging go through it. →
Voltage: The electrical pressure that drives current through a circuit, measured in volts. Supply voltage depends on the service type. →
Voltage drop: The loss of voltage along a conductor due to its resistance, which grows with current and length. Long runs to garages, pumps and chargers often need larger conductors to keep it within limits. → →
Watt: The unit of power, equal to one joule per second. Appliance nameplates list watts, and loads above a set wattage count at full rating in a house load calculation. → →
Wire gauge (AWG): The American Wire Gauge sizing system used in Canada for building wire. Smaller gauge numbers mean thicker conductors that carry more current. →
Wire owner: The utility that owns the distribution system serving a site, ENMAX Power inside Calgary. Micro-generation notices and service connections go to the wire owner, not the retailer. → →

Conductor colours you will see in a panel

Black Ungrounded (hot) conductor
Red Ungrounded (hot) conductor, second leg of a 240 V circuit
Blue Ungrounded (hot) conductor, third phase in three-phase work
White Identified (neutral) conductor
Green Bonding conductor
Bare copper Bonding conductor

General convention for reading a panel. The exact rules are in the Canadian Electrical Code as adopted in Alberta; see the electrical code in Alberta.

Electrical glossary

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Conductor colours you will see in a panel