Electrical Concepts

Clear explanations of the electrical concepts behind real design work: load and demand calculations, protection devices, motors and drives, and the calculations that tie them together. Start with the guides below, or browse every article underneath.

Load Calculations and Demand Factors

• Load Calculation for Commercial Buildings
• Demand Factor for Receptacles (NEC)
• Demand Factor for Multi-Dwelling Units (NEC)
• Demand Factor for EV Charging Stations (NEC)
• Demand Factor for RV Parks
• Diversity Factor for Air Conditioners

Protection and Safety Devices

• Difference Between GFCI and ELCB
• Motor Overcurrent Protection Calculator
• Junction Box vs Pull Box: Differences and Sizing Rules

Motors and Drives

• Motor Service Factor with a VFD
• Motor Overcurrent Protection Calculator

Calculations and Design Tools

• Electrical Circuit Calculations and Relays Guide (USA)
• Street Lighting Voltage Drop Calculation (Free XLS)
• Cable Tray Bending Radius: Minimum Bend Formula
• All Electrical Calculations articles and our Electrical Calculators

Power Systems and Grid Monitoring

• Synchrophasor Measurements and PMU Technology

Demand Factor vs Diversity Factor

Demand factor is the ratio of a system’s maximum demand to its total connected load. It is always 1 or less, and it tells you how much of the installed load will actually run at once. Diversity factor is the sum of the individual maximum demands of the loads divided by the maximum demand of the whole system. It is always 1 or more, and it reflects that loads peak at different times. Both let you size conductors, panels, and transformers without oversizing for a worst case that never happens, but always confirm the factors your local code requires.

All Electrical Concepts Articles