A Load Calculation is an engineered assessment of the electrical demand of a building or development that totals and profiles all fixed and intermittent loads to determine the maximum demand and the correct sizing of supply, metering and protection equipment. It tells you whether the existing main connection is sufficient now and for planned future growth.

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Energy management plan guidelines as used in South Africa, describe how to measure, record and report building energy use, identify peak and base loads, and propose measures for managing demand and compliance. Government and industry guidance (DMRE/SANEDI training modules and EPC guidance) set out steps for load inventory, metering/measurement, and reporting — including when detailed load logging is required. Municipal/distributor codes and national standards (SANS/NRS) then translate those plans into technical requirements for wiring, metering and connection approval.

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Creating a Load Calculation requires a number of steps:

1. To gather building plans, bill history and a list of fixed appliances/equipment (ratings, quantities, duty cycles).
2. To split loads into categories (lighting, sockets, HVAC, motors, special equipment, standby generation).
3. To apply demand factors where appropriate (motor diversity, lighting diversity) or perform measured logging for intermittent/high-power loads.
4. To convert appliance ratings to kW/kVA and produce a time-profile to find the likely maximum demand.
5. To check voltage drop, protection device selection and conductor sizing per SANS 10142 and any local municipality rules.
6. To produce a short report showing calculated maximum demand (kVA), recommended notified maximum demand (NMD) or supply size, and suggested mitigation (e.g., load management or staggered starters).

If high accuracy is required for billing/connection purposes, a measured load study (power logger) over days or weeks would be included.

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• It ensures safety and compliance (correctly sized conductors, breakers and metering).
• Prevents nuisance tripping and unplanned outages by revealing overloads.
• Avoids under- or over-specifying a supply upgrade (saving capital and tariff costs)
• Identifies opportunities to reduce peak demand and energy costs.

Many distributors/municipalities and some certification schemes expect a documented plan for new connections or upgrades.

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Supply size depends on your calculated maximum demand in kVA, your required contingency/future growth, and the distributor’s rules for Notified Maximum Demand (NMD) or Maximum Export Capacity (MEC). After a load calculation an engineer proposes a kVA value; the distribution authority (municipality or Eskom) then confirms the service size and any contractor/connection conditions. For industrial sites the NERSA/municipal rules control demand-based charges—so your engineer will coordinate with the distributor.

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There are two common options:

1. Use online calculators/tools for a quick, indicative estimate, useful for planning.
2. Engage an electrical engineer or consultancy remotely who will produce a formal load study and report using plans, photos, meter data and, if needed, logged measurements. For regulatory or connection applications you’ll usually need a certified engineer’s stamp rather than just a DIY calculator.

Eskom provides household calculators for energy use; professional firms advertise remote load-study services.

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Persistent tripping can be caused by overloaded circuits, incorrect breaker sizing/setting, motor starting currents, poor distribution board design, or faulty equipment. A load calculation plus a site inspection will identify whether the root cause is an overloaded supply, requiring load management or a supply upgrade, or a localized fault that needs repair. SANS wiring code also requires correct protective device selection and testing.

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• A load calculation quantifies the required kVA and peak demand so the distributor can size transformers, service cables, and meters correctly;
• Supports an application for an increased NMD or a higher service category;
• Can demonstrate whether the upgrade is actually needed or whether demand-management (staggering loads, soft starters, energy efficiency) is a lower-cost alternative. Distributors rely on the engineer’s study when approving upgrades.

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At a minimum, building plans (floor plan and services), list of appliances/equipment with nameplate ratings (kW/kVA/Amps), operating schedules/duty cycles, historic electricity bills and meter readings, existing distribution board schedules, planned future loads, and any special equipment (welders, compressors, ovens, lifts).

For greater accuracy, measured current/voltage logs from a power logger, single-line diagrams, and information about local supply voltage and earthing.

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This depends on complexity and method. A desktop calculation from plans for a small residence or simple commercial fit-out can be done in a few hours to a couple of days.

If the engineer requires measured logging (recommended for large or variable industrial loads), the measurement period can be days to weeks (30-day studies are commonly used for precise maximum demand determination).

Allow extra time for coordination with the distributor if a connection or upgrade is involved.

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Costs for load calculations and energy management plans vary depending on property size, complexity, and the level of detail required.

Whether it’s a small residential study or a complex commercial/industrial project, requesting a written quote ensures you know exactly what’s included, the deliverables, and the cost.