Reference

Commercial electrical glossary

127 terms from the switch room, the drawings, the tariff and the contract, in plain language.

Adjudication: A fast, interim-binding dispute process under Alberta’s prompt payment law for payment, valuation and change order disputes. An adjudicator appointed through a Nominating Authority decides within a short statutory period. →
Allowance: A sum carried in a bid for something not yet defined, such as fixtures to be selected. The final cost is adjusted up or down, so a low bid with thin allowances may not stay low. →
Alternate: A separately priced option in a bid, such as a different fixture package or added EV rough-in, that the owner can accept or decline. Alternates let an owner compare scopes without rebidding. →
Annual electrical permit: A yearly facility permit covering ongoing maintenance-type electrical work in one facility. Calgary requires one where a facility employs a full-time journeyman electrician, and a maintenance contractor may also hold one. →
Annunciator: A display, usually at the main entrance, that shows firefighters which zone or device is in alarm. Its labels must match the building as altered, which is often missed on renovations. →
Approved equipment: Electrical equipment bearing a recognized certification mark, such as CSA or cUL, showing it meets Canadian standards. Uncertified equipment must be approved, usually through a field evaluation, before it is connected in Alberta. →
Arc flash: An explosive release of heat, light and pressure when current jumps through air between conductors, often triggered by a dropped tool or failed part. It can cause severe burns at a distance, which is why energized work is avoided wherever possible. →
Arc flash label: The label on switchgear or panels showing the study results for that equipment, such as incident energy and boundaries. It is only valid while the study reflects the current system and settings. →
As-built drawings: Drawings updated at completion to show what was actually installed, including circuit changes and routed feeders. They are the base for every future fit-out and should be a condition of final payment. →
Automatic transfer switch (ATS): A switch that senses loss of utility power, starts or accepts the generator, and moves the connected loads to it, then back again when utility power returns. Life safety loads and optional loads are normally on separate transfer switches. →
Available fault current: The largest current that could flow at a point in the system during a short circuit, set mostly by the utility transformer and the conductors. Every breaker and panel must be rated to interrupt or withstand it, and it drives arc flash energy. →
Base building: The landlord’s shared building systems, such as the service, main distribution, risers and fire alarm, as opposed to the tenant’s fit-out. Calgary requires separate electrical permits for base-building and tenant work. →
Billing demand: The demand ENMAX actually charges on: the greatest of metered demand, ratchet demand and contract demand. Demand-based delivery charges are calculated on it per day. →
Branch circuit: The last circuit in the chain, from a panel breaker to receptacles, lights or a single appliance. Most tenant improvement electrical work is branch circuit work. →
Builders’ lien: A claim registered against the land by an unpaid contractor, subcontractor or supplier. It must be registered within a fixed period after the work is completed or abandoned, or it ceases to exist. →
Busway: Factory-built sections of enclosed copper or aluminium bars that carry large currents in place of cable. It is used for risers in towers and for plug-in power along production lines, and it needs periodic torque checks and thermography like switchgear. →
CAN/ULC-S536: The Canadian standard for inspecting and testing existing fire alarm systems, which Alberta’s fire code requires for the annual inspection. The owner keeps the reports and fixes the deficiencies they list. →
CAN/ULC-S537 verification: The standard for verifying a new or altered fire alarm system device by device before it is accepted. Alberta’s building code requires it, and the verification report is a key handover document. →
Canadian Electrical Code (CEC): CSA C22.1, the installation code adopted in Alberta under the Safety Codes Act. New editions take effect automatically, and work follows the edition in force when it was permitted. →
Change order: A signed amendment that changes the scope, price or schedule of a contract. Agree the price and time before the work is done where possible, because disputed changes are a common adjudication topic. →
Circuit breaker: A resettable device that opens a circuit on overload or short circuit. Large breakers have adjustable trip settings that come from the coordination study and must be tested and recorded as part of maintenance. →
Commissioning: Documented testing that systems work as designed, such as lighting controls, generator transfer and fire alarm interfaces. It is separate from the electrical inspection, which checks code compliance. →
Contract demand: A minimum demand the customer agrees to pay for under a contract with ENMAX, often in exchange for a larger ENMAX investment in a new service. It sets a floor under billing demand for the life of the agreement. →
Coordination study: An engineering study that sets breaker and relay settings so the device nearest a fault trips first and the rest of the building stays on. It is usually done with the short-circuit and arc flash study. →
Cost-plus contract: A contract that pays the contractor’s actual costs plus an agreed fee or markup. It suits unclear or emergency scopes but needs open-book records and a cost ceiling or reporting to control the total. →
CSA C282: The CSA standard for emergency electrical power supply for buildings, covering generator installation, testing and maintenance. Check which edition the fire code references rather than assuming the newest. →
CSA Z462: The Canadian standard for workplace electrical safety, covering energized work, approach boundaries and personal protective equipment. Alberta’s OHS Code does not adopt it by name; an Alberta government technical bulletin recommended it to facility managers, and many employers build their electrical safety programs on it. →
CT cabinet: The sealed enclosure, or switchgear compartment, that holds the utility’s current transformers ahead of the meter. Its size, location and sealing provisions follow the ENMAX metering standard, so it must be approved before the gear is built. →
CT metering: Metering in which the meter reads current through current transformers instead of carrying the full load. ENMAX requires it on larger services, with its own request form and installation checklist. →
Current transformer (CT): A ring-shaped transformer around a conductor that produces a small, proportional current a meter or relay can read. CTs let a meter measure a service too large to pass through the meter itself. →
Customer contribution: The part of ENMAX’s connection cost that exceeds its investment and is paid by the customer. It appears on ENMAX’s written estimate and is separate from the electrical contractor’s price. →
DC fast charger (DCFC): A charger that converts power to DC inside the unit and delivers it directly to the battery for rapid charging. DCFCs are large three-phase loads that often need a new service or transformer and ENMAX involvement. →
Default supplier: The supplier that must serve a larger site that is not eligible for the Rate of Last Resort and cannot get or keep retail service. In ENMAX Power’s Calgary area it is ENMAX Energy Corporation. →
Delivery charges (D&T charges): The distribution and transmission charges on a power bill, set by the wire owner’s approved tariff and separate from the energy price. They include daily service and facilities charges, demand charges and per-kWh charges. →
Demand: The rate at which a site draws power, measured over a short interval, as opposed to the energy it uses over a month. A few minutes of every machine running together can set the demand for the whole billing period. →
Design-bid-build: A delivery method in which an engineer completes the design, contractors bid on it, and the engineer reviews the work. It makes bids easier to compare and keeps the designer working for the owner. →
Design-build: A delivery method in which the electrical contractor carries the design and the installation under one contract. It can save time on straightforward scopes but gives the owner less independent design review. →
Development permit: The City’s planning approval for a use or building on a site, which must be in place before a commercial building permit is issued. A change of use, such as retail to restaurant, may need a new one. →
Dry-type transformer: An air-cooled transformer inside a building, commonly used to step 347/600 V distribution down to 120/208 V for receptacles and small equipment. It gives off heat, so the room must be ventilated and its vents kept clear. →
Electrical permit: The City’s authorization for regulated electrical work, taken out by the electrical contractor’s master electrician. Its fee scales with construction value and it triggers the inspections. →
Electrical preventive maintenance (EPM): A scheduled program of cleaning, torquing, testing and inspecting electrical equipment, usually during planned shutdowns. CSA Z463 is the voluntary Canadian guideline many programs follow. →
Electrical room: The room that holds the service, metering, main distribution and often transformers. Its size, working space, egress, ventilation and freedom from unrelated piping are set by the CEC, the building code and ENMAX’s metering standard. →
Emergency lighting: Lighting that switches on when normal power fails so people can find the exits. It is supplied by battery units or by an emergency generator, and it must be tested on the schedule the fire code sets. →
Emergency power: Power required by the building code for life safety systems such as emergency lighting, fire alarm and fire pumps, supplied by batteries or an emergency generator. Emergency generators are installed and maintained to CSA C282. →
Energization: ENMAX connecting and turning on a new or upgraded service. It happens only after the electrical inspection authority has approved the installation and the retailer has requested it. →
Engineer of record: The professional engineer responsible for a project’s electrical design, who stamps the drawings and reviews shop drawings and the installed work. Changing the design without them can void that responsibility. →
EV energy management system (EVEMS): A system that monitors building or feeder load and throttles EV chargers so the total stays within capacity. The CEC recognizes it in load calculations, which can let a parkade add stalls without a service upgrade. →
EV-ready stall: A parking stall with the circuit, conduit or capacity already provided so a charger can be connected later. Making a parkade EV-ready is often the costly part and the charger the easy part. →
EVSE: Electric vehicle supply equipment: the charger and its cable, connector and controls. The electrical work behind it, from service capacity to the circuit, usually costs more than the unit itself. →
Exclusion: Work a bidder states is not in its price, such as ENMAX charges, permits, after-hours work or fire alarm tie-ins. Exclusions are where apparently similar bids differ most. →
Exit sign: The illuminated sign marking the path to an exit, which must stay lit on emergency power. Changing walls in a fit-out often means moving or adding exit signs. →
Feeder: The conductors running from the main distribution to a panelboard, motor control centre or large piece of equipment. Feeder size, length and voltage drop are what usually limit adding load to a far corner of a building. →
Field evaluation: An on-site evaluation of uncertified, imported or modified equipment by an accredited inspection body, which labels it if it complies. It is often needed for foreign machinery and custom control panels. →
Fire alarm system: The building-wide system of detectors, pull stations, signals and a control unit that warns occupants and, where monitored, calls for help. Altering it in Calgary needs both a building permit and an electrical permit, and the altered system must be verified. →
Ground fault circuit interrupter (GFCI): A receptacle or breaker that trips on a very small leakage current to protect people from shock, required by the CEC near sinks and in wet or damp locations. In kitchens, placement and dedicated circuits matter because nuisance trips can spoil refrigerated food. →
Ground fault protection (GFP): Equipment-level protection on large services and feeders that trips when current leaks to ground, to limit fire and equipment damage. It is different from a GFCI, which protects people at receptacles. →
Grounding and bonding: Connecting the electrical system to earth and tying all metal parts together so a fault clears quickly and exposed metal does not become energized. It is inspected at rough-in and is a common deficiency on renovations. →
Harmonics: Current distortion created by electronic loads such as drives, UPS units, LED drivers and computer power supplies. Harmonics overheat neutrals and transformers and can upset sensitive equipment, so they are measured and mitigated in data rooms and plants. →
Hazardous location: An area where flammable gases, vapours or dusts may be present, such as paint booths, fuel handling or some process areas. Electrical equipment there must be rated for the classification, which affects cost and lead time. →
Holdback: The share of each payment an owner must retain under Alberta’s Prompt Payment and Construction Lien Act, released after the lien period passes. It protects subcontractors and suppliers who could otherwise file liens. →
Hood suppression interlock: The connection that shuts off gas and electric cooking equipment under a kitchen hood when its fire suppression system discharges, and signals the building fire alarm. It spans the hood, gas, electrical and fire alarm trades. →
Incident energy: The heat energy an arc flash could deliver to a worker at a given working distance, calculated in an arc flash study. It sets the protective clothing needed if energized work cannot be avoided. →
Infrared thermography: Scanning energized equipment under load with an infrared camera to find hot connections and overloaded parts before they fail. It is non-contact, but opening covers for the scan is itself energized work that needs precautions. →
Interrupting rating: The highest fault current a breaker or fuse can safely clear. A device whose rating is below the available fault current can fail violently, which is why replacement breakers must match the original specification. →
Interval meter: A meter that records demand and energy in short time blocks rather than as one monthly total. ENMAX installs them on larger sites, and the interval data is the best evidence for sizing a service upgrade or EV charging. →
Investment level: The amount ENMAX will spend toward a new or larger service, set in its approved schedule by rate class and, for larger customers, by contracted demand. It is a credit against the connection cost, not a price. →
K-rated transformer: A dry-type transformer built to tolerate the extra heating caused by harmonic currents. It is specified where many computers, LED drivers or drives share a transformer; a higher K-factor means more harmonic tolerance. →
Kilovolt-ampere (kVA): A unit of apparent power, the product of voltage and current. Transformers and generators are rated in kVA, and ENMAX bills commercial demand in kVA rather than kW. →
Kilowatt (kW): A unit of real power, the rate at which energy is actually used. It equals kVA multiplied by the power factor. →
Kilowatt-hour (kWh): A unit of energy: one kilowatt used for one hour. Energy charges and the retailer’s price are per kWh, while demand charges are based on the peak kVA. →
kVA demand: Demand measured in kilovolt-amperes, which is how ENMAX bills medium and large commercial sites. Because kVA includes the effect of power factor, a site with poor power factor pays for more demand than it uses in kW. →
kWh billing dispensation: Measurement Canada’s temporary permission to bill EV charging by the kWh on chargers not yet approved as revenue meters, with registration and accuracy conditions and an end date. Billing by time or a flat fee is exempt. →
Level 2 charging: AC charging at 208 V or 240 V, the standard choice for workplaces, condos and fleets that park for hours. Many Level 2 stalls can share a service when load management is used. →
Load calculation: The designer’s calculation, under the CEC’s load rules, of the load a service or feeder must carry after applying demand factors. It is a design document; it is not the sum of nameplates or a guess from the building’s size. →
Load management: Controlling when and how much power large flexible loads draw, such as chargers, heaters or compressors, to keep peak demand down. It protects both service capacity and the demand portion of the bill. →
Local Access Fee: A municipal fee the City of Calgary collects through ENMAX’s bill for use of city land by the distribution system. It is billed on top of ENMAX’s delivery charges. →
Lockout: Isolating equipment from its energy sources and securing the isolation with personal locks before work, as the Alberta OHS Code’s hazardous energy rules require. Each worker applies their own lock and verifies the equipment is de-energized. →
Master electrician: The Safety Codes Council certificate that a person must hold for an electrical contractor to obtain electrical permits in Alberta. Owners can check a certificate through the Council’s public search. →
Measurement Canada: The federal agency that regulates meters used for trade, including electricity submeters and kWh-billing EV chargers. Its approval, verification and sealing rules apply on top of provincial electrical rules. →
Motor control centre (MCC): A line-up of sections that house the starters, drives and breakers for many motors in one place. MCCs are standard in plants, pumping stations and large mechanical rooms, and they carry high arc flash energy because of the power they concentrate. →
National Energy Code for Buildings (NECB): The energy code Alberta applies to larger buildings, which sets limits on lighting power, lighting controls and other systems. It shapes lighting design in new buildings and major renovations. →
Nominal voltage (120/208 V and 347/600 V): The two common Canadian commercial systems: 120/208 V for receptacles, small equipment and many retail bays, and 347/600 V for lighting and large loads in bigger buildings. Equipment must be ordered for the system it will connect to. →
Non-ratcheted demand charge: A per-kVA charge on medium and large commercial ENMAX classes that is based on the demand actually metered in the period, not on the ratchet. It sits alongside the ratcheted facilities and transmission demand charges. →
Notice of dispute: The owner’s written notice, within the Act’s deadline, that it will not pay all or part of a proper invoice, with the reasons. Undisputed amounts must still be paid on time. →
Notice of non-payment: The contractor’s notice to a subcontractor that it has not been paid by the owner, with an undertaking to refer the dispute to adjudication. Without it the contractor must pay the subcontractor on the statutory deadline anyway. →
O&M manuals: The operation and maintenance manuals handed over at completion: equipment data, warranties, test reports, settings and maintenance instructions. Facility teams rely on them for every later service call. →
Occupancy permit: The City’s final approval that a building or space is safe to occupy, booked after all required inspections are signed off. A new business licence generally follows it. →
Pad-mount transformer: The utility transformer on a concrete pad outside a building that steps ENMAX’s distribution voltage down to the building’s service voltage. ENMAX needs a clear zone around it for access, so landscaping, fences and parking must keep away. →
Panelboard: The wall-mounted panel of breakers that feeds branch circuits for lighting, receptacles and small equipment. A tenant space usually has one or more panelboards fed from the building’s distribution, and their spare spaces decide how easily the space can take new loads. →
Plans review: The City’s review of electrical drawings submitted with a permit, required for larger services and high-voltage work. Additional review time is billed hourly on non-residential permits, so complete drawings save money. →
Power factor: The ratio of real power (kW) to apparent power (kVA), reduced by motors and some electronic loads. ENMAX requires customers to keep it above a minimum and can require corrective equipment at the customer’s cost. →
Power factor correction: Capacitor banks or active equipment added to bring a site’s power factor closer to one. Because ENMAX bills demand in kVA, improving power factor can lower billing demand as well as meeting the utility’s minimum. →
Primary metered service: A service metered at ENMAX’s distribution voltage, with the customer owning the transformation and everything after it. It suits large sites and campuses and moves more equipment and maintenance onto the owner. →
Proper invoice: An invoice that meets the Act’s content requirements and starts Alberta’s prompt payment clock. Owners must pay it or give a notice of dispute within the statutory time. →
Ratchet: A tariff rule that keeps billing demand from falling below a set share of the highest peak in the past year. One high peak, such as commissioning new equipment on a cold morning, can raise the bill for months afterward. →
Rate class: The ENMAX tariff category a site is billed under. Commercial classes run from D200 small commercial through D300 medium and D310 large secondary to D410 primary service, and a site moves between them based on its energy use and recorded demand. →
Rate of Last Resort (RoLR): Alberta’s regulated default energy rate for eligible customers who do not sign with a retailer, fixed for a set term. Eligibility for businesses depends on the distribution owner’s forecast of the site’s annual consumption. →
Request for information (RFI): A contractor’s written question to the designer about unclear or conflicting drawings. RFIs and their answers become part of the project record and often lead to change orders. →
Retailer: The company that sells the energy itself and sends the bill, which includes the wire owner’s delivery charges. Businesses can choose a retailer; energization of a new site is requested through one. →
Revenue meter: Any meter used to set a charge for electricity, including a submeter that bills tenants or residents. Measurement Canada requires revenue meters to be an approved type and verified and sealed before use. →
Safety Codes Officer (SCO): The designated inspector who reviews permitted work for code compliance. In Calgary, City electrical Safety Codes Officers inspect at rough-in and final and can order corrections. →
Service and facilities charge: The fixed daily charges in ENMAX’s commercial tariff for having a connection and the facilities that serve it. On demand-billed classes the facilities charge is per kVA of billing demand. →
Service entrance: The point where the utility’s supply enters the building and the customer’s equipment begins, including the service conductors, main disconnect and metering. Changing it involves ENMAX, a permit and an outage. →
Shop drawings: The manufacturer’s or contractor’s detailed drawings of equipment such as switchgear, submitted for the engineer’s review before fabrication. Errors caught here cost far less than errors caught on site. →
Shunt trip: A breaker accessory that opens the breaker on a remote signal. In restaurants it is commonly how a hood suppression discharge shuts off electric cooking equipment. →
Single-line diagram: A simplified drawing of the power system from the utility supply through the switchgear, transformers and feeders, with ratings. ENMAX asks for one for commercial services, and it is the most useful document a facility can keep current. →
Site ID: The unique identifier ENMAX assigns to a metered point of service. The retailer needs it before it can enrol the site and request energization, so it should be set up before the final inspection. →
Special inspection label: The label an accredited body applies to a specific piece of equipment after a field evaluation, allowing it to be installed and inspected. Plan for the evaluation before the equipment ships. →
Splitter: An enclosure with bus bars that lets one set of incoming conductors feed several disconnects or panels. Splitters are common in older plazas and are often the first thing an engineer reviews when a tenant needs more power. →
STANDATA: Alberta’s official bulletins that interpret the adopted codes or grant variances, published by the Safety Codes system. They can change how a code rule applies in Alberta, so designers check them alongside the code. →
Standby power: Backup power the owner chooses for business continuity, such as keeping refrigeration, servers or production running. It is optional, is kept separate from life safety loads, and is sized on business needs. →
Stipulated price contract: A contract for a fixed lump sum for a defined scope, adjusted only by change orders. It suits complete drawings and puts quantity risk on the contractor. →
Submetering: Metering tenants or suites downstream of the utility meter. If the readings are used to bill, the submeters are revenue meters under federal rules, and ENMAX’s own standard also restricts resale and double metering. →
Substantial performance: The point at which the work is ready for its intended use, certified under the contract. It starts important clocks, including holdback release. →
Switchboard: A free-standing assembly, lighter than switchgear, that holds the main disconnect and the feeder breakers for a building. Many mid-size commercial and apartment buildings have a switchboard rather than switchgear; the difference matters for maintenance, access and replacement parts. →
Switchgear: Heavy-duty assemblies of breakers or fused switches, usually in metal-clad sections, that receive a large service and divide it into feeders. It is built to order, so its lead time and its fit in the electrical room are often the critical path on a new service. →
Temporary construction service: A short-term utility service that powers a construction site until the permanent service is ready. ENMAX may charge its full cost, and Calgary requires specific protection ahead of the meter. →
Tenant improvement (TI): The construction that fits out leased space for a tenant, also called a fit-out. It needs its own building and trade permits and often involves the landlord’s approvals and shutdown rules. →
Three-phase power: A supply with three alternating voltages offset in time, which delivers more power over the same conductors and runs motors smoothly. Almost all commercial buildings and larger equipment use it. →
Transformer vault: A fire-rated, ventilated room inside or under a building that houses utility transformers, built by the customer to the utility’s specification. Vaults are typical of large downtown services on ENMAX’s network system. →
Uninterruptible power supply (UPS): Battery-backed equipment that keeps computers, controls or other sensitive loads running through a power interruption until a generator starts or the load shuts down safely. Its batteries need replacement on a schedule and add heat to the room. →
Unit equipment: Self-contained emergency lighting units with their own battery and charger, often called battery packs. They are simple to add in a fit-out but need regular testing and battery replacement. →
Variable frequency drive (VFD): An electronic controller that varies a motor’s speed by changing the frequency of its supply. VFDs save energy on fans and pumps but draw distorted current, so they are a common source of harmonics. →
Voltage drop: The loss of voltage along a conductor, which grows with current and distance. Long feeders to parkades, rooftop units or far warehouse bays are often upsized to keep equipment voltage within limits. →
Wire owner: The regulated utility that owns the distribution wires and delivers power to the site. In Calgary this is ENMAX Power, which charges its approved tariff whichever retailer sells the energy. →
Work letter: The part of a commercial lease that splits the construction between landlord and tenant. For electrical work it should state the power delivered to the premises, metering and who pays for upgrades. →
Working space: The clear space the CEC requires in front of electrical equipment so a worker can operate and maintain it safely. It depends on the voltage and what is opposite the equipment, and it can never be used for storage. →

Conductor colours in commercial panels

Red Phase A (ungrounded conductor)
Black Phase B (ungrounded conductor)
Blue Phase C (ungrounded conductor)
White Identified (neutral) conductor
Green 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.

Commercial electrical glossary

A

B

C

D

E

F

G

H

I

K

L

M

N

O

P

R

S

T

U

V

W

Conductor colours in commercial panels