Reference
Commercial electrical glossary
34 terms from the switch room, the drawings, the tariff and the contract, in plain language.
- Apparent power
- Power expressed in volt-amperes; a planning quantity distinct from real power and energy.
- Arc flash study
- An assessment using system data and modelling to inform electrical hazard evaluation.
- Automatic transfer switch
- Equipment that transfers a connected load between specified sources under its designed control sequence.
- Base building
- The landlord or owner’s common building systems and provisions, distinct from a tenant’s fit-out.
- Branch circuit
- The circuit supplying utilization equipment downstream of its final overcurrent protection.
- Commissioning
- A documented process of checking that installed systems perform their agreed functions.
- Coordination study
- An assessment of protective devices and their operating relationships within a distribution system.
- CT metering
- Metering that uses current transformers as part of an instrument measurement arrangement.
- Demand
- A measure of power required over a specified interval, distinct from accumulated energy consumption.
- Design-build
- A delivery arrangement in which design and construction are coordinated through a combined contract.
- Distribution
- The system carrying power from the building supply to downstream equipment and circuits.
- Electrical permit
- Authority approval for a defined scope of regulated electrical work.
- Energization
- Putting electrical equipment or a service into an energized state through an authorized process.
- EVEMS
- An electric vehicle energy management system controlling charging loads within an assessed arrangement.
- Feeder
- Conductors supplying downstream distribution or equipment from an upstream source.
- Holdback
- An amount retained under applicable construction legislation or contract arrangements, subject to release conditions.
- kVA
- Kilovolt-amperes, a unit of apparent power.
- kW
- Kilowatts, a unit of real power.
- kWh
- Kilowatt-hours, a unit of energy rather than instantaneous power.
- Load management
- Control of electrical loads to fit an assessed supply or operating constraint.
- Motor control centre
- An assembly organizing motor control and associated distribution equipment.
- One-line diagram
- A simplified drawing showing the main relationships in an electrical distribution system.
- Panelboard
- An assembly distributing circuits through associated switching and protective devices.
- Power factor
- The relationship between real and apparent power for the specified electrical conditions.
- Proper invoice
- An invoice meeting the applicable statutory and contractual requirements in a prompt-payment framework.
- Scope of work
- The defined deliverables, responsibilities, boundaries and exclusions of a project.
- Switchgear
- An assembly of switching, protection and related electrical equipment.
- Tenant improvement
- Work adapting leased premises for a tenant’s use.
- Thermography
- Thermal imaging used by qualified personnel to record and assess temperature observations.
- Three-phase
- An alternating-current arrangement with three phase relationships, used in many commercial power systems.
- Transformer
- Equipment transferring electrical energy between circuits, commonly used to change voltage.
- UPS
- An uninterruptible power supply intended to support specified loads through defined interruptions.
- Verification
- A documented assessment of an installation or alteration against the relevant requirements; distinct from routine inspection.
- VFD
- A variable-frequency drive used to control an appropriate motor’s operating characteristics.
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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.