Articles: Low Voltage Design

Seven major changes in AS/NZS 3008.1.1:2025 for cable sizing — new DC tables, multi-row correction factors, 110 °C aluminium ratings, voltage rise, and short-circuit limits.

Learn how to size cables using NEC (NFPA 70) with step-by-step calculation examples, including ampacity, voltage drop, OCPD, and EGC sizing.

Advanced voltage drop calculations for electrical cables. Learn how power factor, cable temperature, impedance, motors, and installation conditions affect voltage drop.

Learn how to set priorities and adjust protective devices for selective coordination to isolate faults and minimise outages in electrical systems.

Learn how to set and coordinate circuit breakers to meet AS/NZS 3000:2018, ensuring faults are isolated quickly and safely in electrical systems.

Size active, neutral, and earth cables using AS/NZS 3008. The guide covers current capacity, voltage drop, and short-circuit calculations with examples.

Miniature Circuit Breakers (MCBs) protect against overcurrent in electrical circuits. MCBs are categorised based on their tripping characteristics, represented by different device curves such as Z, B, C, K, and D. This article offers guidance on selecting the right type for your application.

The AS/NZS 3000 Standard provides different rules in Appendix C for maximum demand with socket-outlets for domestic, commercial, and industrial electrical installations. Calculation examples are provided involving double socket-outlets.

The principle of economic cable sizing is to select a minimum cable size that is safe to use and the cost of the losses over the lifetime is also minimised.

Equations for calculating conduit sizes and space factors in accordance with standards are provided. Worked examples of conduit sizing calculations are provided.

The fault current which flows in a power cable causes its temperature to rise dramatically. The adiabatic equations for calculating the minimum conductor size to withstand the short circuit are explained.

The definition of “touch voltage” is the voltage between accessible exposed and extraneous conductive parts that may lead to the risk of electric shock in the event of an electrical fault. This article covers AS/NZS 3000, BS 7671, and NFPA 70E rules concerning touch voltages and provides the equations for calculations.

DC cable sizing has significant implications on a PV system’s performance, total cost, and safety. Example calculations of Current Rating and Voltage Rise have been provided.

Equations and method with all steps for accurate voltage drop calculations including power factor, cable operating temperature, resistance, reactance, DC, 1-phase or 3-phase, balanced/unbalanced with calculation examples provided.

This article explains how to properly size earth conductors for earth faults and includes the method, equations, constants you can use and worked examples to follow.

There are several international Standards (AS/NZS, BS and IEC) which cover requirements for protection coordination of low voltage electrical systems and this article provides a summary of those as a reference.

Download the attached PDF report template and use it for your solar connection applications.

This article explains how to perform cable pulling tension and sidewall pressure calculations and also includes an example.

The new maximum demand module provides fast and accurate calculations for loads in accordance with rules from the Standards and for custom loads. An ingenious automatic phase balancing algorithm ensures maximum demand and phase imbalance are both minimised.

The neutral conductor is required for each primary circuit, and there are rules in the Standards for its sizing.

Voltage rise can occur in solar PV systems on the AC side between the power inverters and network connection point. Voltage rise calculations are no different to those for voltage drop.

Accurately calculating voltage drop results in lower voltage drops which leads to smaller cable sizes and saves money.

The purpose of this document is to provide a better understanding of Fault Loop Impedance, also referred to as Earth Fault Loop Impedance so that the requirements of AS/NZS 3000 Wiring Rules for safety, design, installation and testing of electrical installation may be met.

Voltage Drop Limits per the Wiring Rules AS/NZS 3000 as well as rules of thumb to assist with electrical design. Includes AC and DC voltage drop or rise limits.

Derating factors are applied to the cable current rating ensuring that cable operating temperature limits are not exceeded. Derating factors are derived to match the specific cable installation conditions.

Discussion of the changes to AS/NZS 3000:2018 affecting cable current-carrying capacity.

Reference tables for diversity factors and energy demand from Wiring Rules AS/NZ 3000 for domestic and non-domestic installations.

The 4 main approaches for determining the maximum demand of an electrical installation are discussed.