Load Survey and Current Loggers

Use this guide when you need to know how much current a circuit, feeder, transformer, distribution board or item of equipment carries over time.

A load survey gives recorded proof of real operating current, peak demand and usage patterns. It is useful before adding new loads, checking spare capacity, investigating overloaded circuits, reviewing feeder demand or comparing equipment behaviour over a normal working period.

When to run a load survey

• You need to check whether a feeder, distribution board, transformer or cable is close to its practical limit.
• You are planning new equipment, EV charging, heating, cooling, process loads or other added demand.
• You need to understand current profile, peak current, duty cycle or operating hours.
• You want proof before resizing equipment, changing protection, upgrading supply capacity or balancing phases.
• You need to compare current demand between shifts, weekdays, weekends or production cycles.

What to measure

• Single-phase or three-phase current over time.
• Minimum, maximum and average current.
• Peak demand and load profile.
• Phase loading and imbalance on three-phase supplies.
• Where required, voltage, kW, kVA, kVAR, power factor and energy at the same time as current.

Recommended loggers

Quick comparison

Use this table as a quick route from the investigation type to the most likely logger.

How to choose

• Choose EC-7VAR-RS when current alone is not enough and you also need voltage, power, energy or power factor.
• Choose EC-3A-RS for high-current three-phase surveys, larger conductors or situations where flexible Rogowski coils make installation easier.
• Choose CT-3A-RS for three-phase current surveys where clamp-on CTs fit the conductors and the expected range suits the CT option.
• Choose CT-1A for single-phase current surveys and smaller individual circuits.

Typical load survey workflow

• Identify the circuit or feeder to be checked and the expected current range.
• Choose a logger and sensor type that fits the conductors and expected current.
• Record long enough to include representative operation, such as shifts, start-up periods, weekends or production cycles.
• Review peak current, average current, phase balance and periods of unusual demand.
• Use the results to support capacity planning, energy audit work, EV charger planning, equipment checks or upgrade decisions.

Useful reading

• Energy Auditing
• EV Charging
• Recording Electrical Energy Use is Easy
• Performing an Energy Audit
• Products by Use: load surveys, current logging and feeder checks

Need help choosing?

If you are not sure which current logger is best for a load survey, contact us with the supply type, conductor size, expected current range and what decision the survey needs to support.