Modern electronic lifestyle products provide numerous benefits but are vulnerable to electrical transients that can cause significant damage. The Australian Lightning Protection Standard AS 1768 outlines a comprehensive risk assessment procedure to evaluate the impact of lightning on electrical systems and structures. Research indicates that up to 85% of all electrical transients originate from within these installations themselves.

While surge and lightning protection may be perceived as complex, it’s important to consider them as essential insurance for protecting your electrical assets. You can prevent potential lightning hazards to your equipment and installations by adhering to a few straightforward guidelines:

1.  Differentiate between lightning and other surge protections.

There are two main types of surge protection devices (SPDs) -- primary protection and secondary protection. Depending on the risk, a Type 1 or Type 1+2 SPD can be used for primary protection against lightning. You typically place them near the service entrance, where the risk of direct lightning strikes is higher.These devices are tested with a high energy impulse current (I_imp), with a waveform defined as 10/350, which is designed to recreate the effects of lightning current. Primary protection include voltage switching devices such as spark gaps tht can handle high-energy impacts.

2. Implement secondary protection.

Secondary protection is often a Type 2 SPD using voltage limiting devices such as varistors. These devices are tested with an 8/20 waveform (I_max) to recreate the transients generated from distant lightning strikes, grid switching, motors and other load switching.The energy handling capacity significantly differs between Type 1 (10/350 rated) and Type 2 (8/20 rated) SPDs. Choosing between the two should be based on thorough risk assessment of your installation.

The Wiring Rules AS/NZS 3000 provide valuable guidelines on installing surge protection. In domestic settings, an SPD with a maximum discharge (I_max) rating of 40kA is usually sufficient. However, for areas with higher lightning risk or in industrial and commercial applications, an I_max of 100kA is recommended.The Lightning Protection Standard AS 1768 suggests considering ratings above 100kA for higher-risk scenarios.

You can refer to this table for the minimum protection level for each zone:

Guidelines for Installing SPDs:

• Keep the lead lengths as short as possible. This includes the supply connection and the earth connection. The standards recommend not more than 1 metre total, preferably 300-600mm.
• Keep the wiring as straight as possible with minimal bends. Lightning currents do not like going around corners.
• The minimum wiring size is 6mm² according to the standards. Larger cable size is better, up to the terminal capacity of the SPD.
• Install upstream protection according to the manufacturer’s recommendation.
• Install SPDs above RCD protection.
• Where there is a cable run longer than 10 metres between an SPD protected switchboard and equipment where protection is required, additional surge protection should be installed.
• Surge protection devices are designed to protect against multiple surges over time. Status indication of a visual flag or LED to a signalling contact can be used to monitor the health of the SPD.
• In final sub-circuit or signal and data SPD applications, separate the wiring of the ‘unprotected’ supply side of the SPD from the ‘protected’ load side of the SPD to avoid electromagnetic coupling of the surge.

Surge protection solutions are readily available, simple to implement, and cost-effective relative to the value of the equipment they safeguard.

IPD offers a comprehensive range of solutions from leading manufacturers such as Dehn and Novaris, coupled with expert application assistance to ensure optimal site protection.

For more information, contact IPD at 1300 556 601 or visit our website.