Rainy Season Lightning Protection and Power Distribution Protection

"It was three o'clock in the morning, and the workshop suddenly went completely dark, with all machines shutting down and a slight burning smell coming from the distribution box——" This is a personal experience of Mr. Ahmad, the operation and maintenance supervisor of an electronic component factory in Penang, Malaysia. Last week, a heavy thunderstorm hit the area. Due to the incomplete lightning protection of the factory's power distribution system, lightning-induced voltage surged into the lines and directly broke down the main circuit breaker of the workshop, resulting in a production suspension of more than 8 hours for the entire factory. This not only caused a loss of nearly MYR 55,000 in orders but also an additional MYR 13,000 in costs for replacing the circuit breaker and inspecting the lines. Entering the rainy season, thunderstorms occur frequently. As an "invisible killer" of power distribution systems, lightning often causes faults such as circuit breaker damage, line short circuits, and equipment burnout, and may even lead to safety accidents such as fires and electric shocks. For various scenarios such as industrial plants, office buildings, parks, and new energy power stations, doing a good job in lightning protection and power distribution protection during the rainy season, especially the lightning protection of core equipment such as circuit breakers, is no longer an "optional action", but a "must-answer question" to ensure the normal operation of production and life and avoid property losses.

The core pain point of lightning protection in the rainy season is: lightning has various forms of damage (direct lightning strike, induced lightning strike, lightning wave intrusion) and is sudden and highly destructive. In the power distribution system, circuit breakers, as the "safety guards" of lines and equipment, are not only a key link in lightning protection but also one of the most vulnerable equipment to lightning strikes. Many enterprises often have cognitive misunderstandings, leading to the failure of lightning protection and ultimately causing equipment damage and economic losses. In fact, lightning protection for power distribution in the rainy season is a systematic project, focusing on the three core principles of "interception, diversion, and protection". The three most critical key points are as follows, which are detailed with specific cases to help you quickly grasp the core methods:

Key Point 1: Choose the Right Lightning-Protected Circuit Breaker to Build the "First Line of Defense" for Power Distribution Protection

As the core protection equipment of the power distribution system, the lightning protection performance of circuit breakers directly determines the ability of the power distribution system to resist lightning strikes. The instantaneous high voltage and large current caused by lightning in the rainy season can easily break down the insulation layer of ordinary circuit breakers, leading to mis-tripping, damage of circuit breakers, and even line short circuits. Therefore, the top priority of power distribution protection in the rainy season is to select special circuit breakers with lightning protection functions according to scene requirements, rather than ordinary circuit breakers. Please pay attention to the following 2 points:

1.Precise Selection to Adapt to Scenarios: Lightning-protected circuit breakers are not "one-size-fits-all" and need to be selected based on 2 core dimensions:

① Voltage level: Match the rated voltage of the power distribution system to avoid overload or insufficient protection;

② Lightning activity intensity: For areas with frequent lightning (such as coastal areas and mountainous areas in Southeast Asia), prioritize products with surge withstand capacity ≥20kA. Outdoor scenarios need to additionally meet the protection level of IP54 or above to resist high temperature, high humidity and rain erosion.

2.Coordinated Work, Indispensable: Lightning-protected circuit breakers need to work in coordination with Surge Protective Devices (SPD) to maximize the lightning protection effect — SPD is responsible for intercepting instantaneous surge voltage in the line (which can intercept more than 80% of induced lightning surges), and the circuit breaker is responsible for quickly cutting off the line within 0.1 seconds when the surge current is too large, so as to avoid secondary short-circuit faults caused by the damage of SPD.

Combine with the actual cases of factories in Southeast Asia to better understand the importance of selection:

-Case of an Industrial Park in Penang, Malaysia: The industrial park had repeatedly encountered power distribution faults in the rainy season before. After thunderstorms, more than 60% of the factories had circuit breaker tripping and equipment failure to start. The operation and maintenance personnel found that all the damaged ones were ordinary low-voltage circuit breakers, whose insulation layer was broken down by lightning-induced voltage. Each maintenance and replacement took 1-2 days, and the average daily production suspension loss per factory was about MYR 8,000. Before the arrival of the 2025 rainy season, the industrial park completed 3 upgrades: ① Selected lightning surge-proof Molded Case Circuit Breakers (MCCB) according to the factory scenarios; ② Installed suitable SPD in the distribution box to achieve linkage protection; ③ Installed rainproof shields for circuit breakers of outdoor lines. After the upgrade, the industrial park experienced 8 severe thunderstorms, and there was no more circuit breaker breakdown or equipment burnout. Only 1 instantaneous surge occurred, which was reset within 10 minutes, causing no production loss.

-Supplementary  Selection Reminder (Precisely adapt to different scenarios and avoid selection pitfalls):

✅ Outdoor scenarios (photovoltaic power stations, outdoor distribution rooms, outdoor factory lines): Prioritize lightning-protected circuit breakers with protection level IP54 or above and surge withstand capacity ≥20kA, which can resist rain and dust intrusion and adapt to the high temperature and high humidity environment in the rainy season in Southeast Asia.

✅ Indoor scenarios (office buildings, office buildings, small factories): Ordinary lightning-protected circuit breakers can be selected, but it is necessary to ensure that they match the SPD (the rated voltage of SPD must be consistent with the rated voltage of the circuit breaker) to avoid protection failure caused by improper selection.

Key Point 2: Ensure the Linkage of Lightning Protection Devices to Avoid the Hidden Danger of "Single-Point Protection"

A common misunderstanding of lightning protection in many enterprises is "single-point protection" — only installing lightning rods or only replacing lightning-protected circuit breakers, but ignoring the systematic linkage of lightning protection devices, which ultimately leads to protection failure. In fact, lightning protection in the rainy season needs to form a complete system of "external interception, internal diversion, and terminal protection", which can be specifically divided into 3 core steps, while avoiding 2 key hidden dangers:

1.Build a Complete Lightning Protection System: Clarify the linkage of 4 core links, none of which can be missing. External interception: Intercept direct lightning strikes through lightning rods/lightning strips and introduce lightning into the ground;

2.Internal diversion: Intercept induced lightning strikes and lightning wave intrusion through SPD on the line;

3.Terminal protection: The circuit breaker is linked with SPD to quickly cut off excessive surge current and protect equipment and lines;

4.Grounding diversion: Quickly divert lightning current to the ground through a qualified grounding system to avoid current retention.

5.Avoid 2 High-Frequency Hidden Dangers (Most easily ignored but most likely to cause faults). Excessive grounding resistance: Specifications require that the grounding resistance of industrial plants ≤4Ω, and that of office buildings and residences ≤10Ω; if the grounding resistance is too large (such as more than 10Ω), the lightning current cannot be diverted quickly, which will reversely intrude into the power distribution system and break down circuit breakers and equipment.

6.Failure of device linkage: If the circuit breaker is not linked with SPD, after SPD intercepts the surge, it cannot cut off the line in time, which will cause SPD burnout and then lead to line short circuit and expand losses.

Combine with actual scenarios in Southeast Asia to see how to solve lightning protection hidden dangers by improving the linkage system:

-Case of an Auto Parts Processing Factory in Jakarta, Indonesia: The factory has many precision equipment such as motors and inverters, which are highly sensitive to lightning surges. Previously, due to ignoring the lightning protection at the front end of the equipment, 3 inverters were burned out by lightning in the rainy season, with a direct loss of more than MYR 100,000. Later, targeted optimization was carried out: install special SPD at the front end of the equipment, matched with small lightning-protected circuit breakers to achieve "hierarchical protection and precise protection". After the transformation, there was no more burnout of precision equipment.

In addition, for industrial plants, equipment such as motors, inverters, and precision instruments are more sensitive to lightning surges. In addition to doing a good job in lightning protection of the main power distribution and sub-power distribution, it is also necessary to install special SPD at the front end of the equipment, matched with small lightning-protected circuit breakers to achieve "hierarchical protection and precise protection", so as to avoid lightning surges intruding through the equipment lines and burning out precision equipment. 

Key Point 3: Daily Inspection and Maintenance to Troubleshoot Lightning Protection Hidden Dangers in Advance

Thunderstorms occur frequently in the rainy season. The lightning protection of the power distribution system not only needs to "select the right equipment and do a good job in linkage", but also needs "daily inspection and troubleshooting in advance" — according to statistics, more than 60% of the power distribution faults in the rainy season are not caused by improper equipment selection, but by inadequate daily maintenance, leading to the failure of lightning protection devices and the decline of circuit breaker performance. Especially in the high temperature and high humidity environment of the rainy season in Southeast Asia, it is very easy to cause oxidation of circuit breaker contacts, aging of insulation layers, attenuation of SPD performance, and loosening of the grounding system. There are 3 key points for daily inspection and maintenance, which are detailed with specific cases:

1.Circuit Breaker Inspection (Once a Week, Additional Inspection After Thunderstorms) 

Key inspection: Whether the insulation layer is damaged, whether the contacts are oxidized, and whether the tripping mechanism is sensitive, so as to avoid poor contact caused by contact oxidation and mis-tripping.

✅ Case Reference: A textile factory in Penang, Malaysia, once had a situation where the circuit breaker could not be reset after mis-tripping in the rainy season. The investigation found that the circuit breaker contacts were severely oxidized due to high temperature and high humidity. Each fault caused a production suspension of 1 hour, with a loss of about MYR 1,200. Later, an inspection system was established to clean contact dust, check the insulation layer every week, and replace aging parts in time, thus completely eliminating such faults.

2.SPD Inspection (Once Every Half Month)

Key inspection: Check the indicator light status (green = normal, red = failure), regularly test the performance, and replace it immediately if it fails, so as to avoid losing the surge interception capacity due to SPD failure.

3.Grounding System Inspection (Once a Month, Once Every 10 Days in the Rainy Season) 

Key inspection: Whether the grounding electrode is loose or corroded, regularly measure the grounding resistance to ensure it meets the specifications (industrial plants ≤4Ω, office buildings and residences ≤10Ω). In the rainy season, the soil humidity is high, so it is necessary to adjust and optimize in time to avoid the increase of grounding resistance.

Second, check the status of SPD, observe whether the indicator light is normal (green for normal, red for failure), regularly test the performance of SPD, test it once every half month in the rainy season, and replace it immediately if it fails. A supermarket had a lightning surge intruding into the line due to SPD failure in the rainy season, breaking down the main circuit breaker, leading to a comprehensive power outage of 4 hours, with a loss of nearly 30,000 RMB. After the incident, it was found that the SPD had long been invalid but not found and replaced in time, becoming a safety hazard.

Third, check the grounding system, observe whether the grounding electrode is loose or corroded, regularly measure the grounding resistance to ensure it meets the specifications (industrial plants ≤4Ω, office buildings and residences ≤10Ω). In the rainy season, the soil humidity is high, which is easy to cause the increase of grounding resistance, so it is necessary to adjust and optimize in time. An outdoor distribution room in an industrial park had loose grounding electrodes in the rainy season, and the grounding resistance rose to 12Ω. After the thunderstorm, the lightning current could not be diverted quickly, breaking down the circuit breaker and SPD in the distribution room, with a maintenance cost of more than 15,000 RMB. Later, the grounding system was regularly inspected, the grounding electrode was tightened in time, and grounding materials were supplemented to ensure that the grounding resistance was stably within the specification range.