According to Section 3.6 of AS/NZS 3000:2018, the maximum limits for voltage drop between the point of supply for an LV electrical installation and any point within that system must not exceed 5% of the nominal voltage. This requirement is vital for ensuring that electrical devices receive adequate voltage, preventing malfunctions and prolonging equipment lifespan.

Special Considerations for Substations

When the point of supply is a dedicated low voltage substation located on the premises, the permissible voltage drop increases to 7%. This allowance reflects the fact that being close to the substation can mitigate some voltage drop effects, ensuring that system performance remains robust.

Stand-Alone Systems

For stand-alone systems, specific design criteria must be met. These systems must be configured so that the combination of the output voltage from the source and the voltage drop does not cause the utilization voltage to fall below 11% of the nominal supply voltage under normal operating conditions. This careful design approach is essential for maintaining the efficiency and reliability of all connected devices.

Guidelines for Voltage Drop Limits

To assist in designing electrical systems, the following practical guidelines can be employed:

• • A voltage drop allowance of 0.5% is recommended for consumers mains, the initial segment of the electrical installation. This ensures maximum voltage integrity.
• • For sub-mains, a voltage drop of 1.5% to 2% is acceptable. This segment branches from the consumers mains and must maintain sufficient voltage for various applications.
• • Final subcircuits may allow for a maximum voltage drop of 2.5%, with considerations for the upstream circuits to ensure overall system integrity.

Voltage Rise Limits for Solar Installations

As renewable energy sources, such as solar power, become more integrated into electrical systems, understanding voltage rise limits is essential. The AS/NZS 4777.1:2016 standard specifies that voltage rise from the inverter to the connection point must not exceed 2%. This limitation prevents excessive voltage levels in the electrical network, safeguarding against safety concerns and potential equipment damage.

In terms of direct current (DC) systems, the AS/NZS 5033:2014 standard states that the maximum voltage drop should not exceed 3%. This limit is critical for ensuring the efficiency of solar panels and ensuring that energy produced is effectively transmitted to the inverter with minimal losses.

Conclusion

In summary, understanding and adhering to the maximum limits for voltage drop and rise as outlined in AS/NZS standards is essential for the effective design and operation of low voltage electrical installations. By maintaining voltage drop within the specified thresholds, electrical systems can operate safely and efficiently, ensuring optimal performance of all connected devices.

These regulations not only ensure compliance with legal standards but also enhance the reliability and efficiency of electrical installations. Whether working with traditional LV systems or integrating renewable energy solutions, prioritizing voltage drop and rise limits is key to achieving a safe and effective electrical infrastructure.