Surge Protection in PE Power Exam

Have you ever experienced a power surge? You know, that sudden increase in electrical current that can cause damage to your appliances or electronics? It’s not a pleasant experience, primarily if you’ve invested much money in your equipment.

Well, imagine if that surge happened on a larger scale – in an industrial setting or a power plant. The consequences could be catastrophic, not just for the equipment but for human lives as well.

That’s where surge protection comes in. Any PE power exam aspirant needs to cover all aspects of surge protection in the PE power exam preparation. Surge protection devices (SPDs) are designed to protect electrical equipment from transient overvoltages that can cause damage or failure.

But how do they work? What types of SPDs are there? And how can you ensure that you’re using the right one for your application? In this blog, we’ll answer these questions and more. We’ll explore the fundamentals of surge protection in the PE power exam, from the physics of surges to the different types of SPDs available.

Let’s discuss this in detail.

Importance of Surge Protection in Power Systems

Importance of Surge Protection in Power Systems

Power systems are integral to modern-day society, powering everything from homes to hospitals, businesses to factories. However, with great power comes great responsibility.

Electrical surges from lightning strikes, switching operations, or other sources can seriously threaten power equipment and those who rely on them.

In this blog, we will explore the importance of surge protection in power systems, discussing the various sources of electrical surges, the damage they can cause, and the economic and safety implications of such surges.

From the standpoint of surge protection in the PE power exam, we will also explain how surge protection can mitigate these risks, helping to ensure the smooth and safe operation of power systems.

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Discussion of the various sources of electrical surges in power systems

Surges are a common issue faced in power systems, and they can arise from internal and external sources.

Internal Sources

Power-switching devices are among the most frequent causes of internal surges in a building. These can range from a thermostat controlling a heating element to a switch-mode power supply, commonly found in electronic devices.

These devices can cause sudden and intense surges due to their inherent nature of switching on and off quickly, resulting in rapid changes in current and voltage levels. These surges can damage electrical systems lacking surge protection components and even shorten the lifespan of the equipment.

Switching of Electrical Loads

Switching and operating electrical loads is a regular and necessary part of everyday operations in the electrical system. However, these operations can also be a source of surges that can cause damage to equipment over time.

Inductive device discharge, starting and stopping loads, fault or arc initiation, arcing faults, fault clearing or interruption, power system recovery from outages, and loose connections are all sources of switching surges.

Imagine a large office building where everyone is using their computers at the same time. When the power goes out, the generators kick in to keep the building running. When the power comes back on, the generators switch off, and the building switches back to the regular power source.

This type of switching can cause a surge that may not be immediately noticeable but can be damaging over time.

Magnetic and Inductive Coupling

When electric current flows, a magnetic field can extend to nearby wires and induce a voltage. This is known as magnetic and inductive coupling, and it can cause transient surges that can damage equipment.

Elevators, heating, ventilation and air conditioning systems (HVAC) with variable frequency drives, fluorescent light ballasts, copy machines, and computers are all examples of equipment that can cause inductive coupling.

For example, let’s say there is a large office building with multiple floors. The elevators operate regularly, creating a magnetic field that can extend to the nearby wiring. This can induce a voltage in those wires and cause a surge that can damage equipment.

Static Electricity

Static electricity, or electrostatic discharge (ESD) phenomena, can generate electromagnetic fields spanning a range of frequencies. These fields can reach up to the low gigahertz range, and an ESD event includes not only the discharge current but also the electromagnetic fields and corona effects before and during the discharge.

ESD results in a sudden charge transfer between bodies of different electrostatic potentials, which can cause high-frequency noise that can interfere with the electrical distribution system.

Imagine a laboratory where various electronic devices and equipment are susceptible to ESD. When a technician walks across the room and touches one of these devices, the resulting discharge can cause a surge that can damage the equipment.

This is why it’s important to ground oneself and use proper ESD precautions when working with sensitive equipment.

External Sources

External surges, on the other hand, can arise from lightning strikes or utility grid-switching operations. Lightning strikes, in particular, can cause massive surges that travel through power lines, potentially damaging equipment in their path.

Grid-switching operations can also generate surges due to sudden changes in voltage and current levels, resulting in potential damage to equipment.


Lightning is the most recognizable and potentially catastrophic source of surges generated outside the facility. Lightning can directly strike a facility’s electrical system or nearby lightning can induce electrical surges in the power or communication systems, causing immediate damage to the system and connected loads.

Grid and Capacitor Bank Switching

Utility-initiated grid and capacitor bank switching can also cause surges. When the power supply is switched to another source or temporarily interrupted to clear a fault from the system, it can cause surges when the power is disconnected and reconnected to customer loads.

Explanation of the damage that surges can cause to power equipment

Electric surges can wreak havoc on your home electronics and appliances, causing immediate damage or slowly degrading them over time. They can also cause significant issues in complex systems, like the avionics in an aeroplane.

  • Industrial – Electrical surges in factories and manufacturing plants can be costly and disruptive, damaging sensitive equipment and bringing production to a halt. Surge protection devices are essential to prevent this and keep operations running smoothly.
  • Domestic –  In households, electrical surges can wreak havoc on electronic devices like TVs and computers. Surge protectors are a simple and cost-effective solution to safeguard against surges caused by lightning strikes or appliances turning on and off, saving homeowners from the hassle and expense of replacing their electronics.
  • Commercial – Electrical surges in commercial settings can damage electronics and pose a safety risk, affecting security and fire alarm systems. Surge protection devices are crucial to ensure the safety of occupants and protect equipment from damage, avoiding costly downtime and repairs.

In fact, electrical surges have been linked to several aeroplane crashes over the years. One such event occurred in 1996 when the fuel tank of a Boeing 747 exploded mid-flight, killing all 230 passengers and crew on board.

The cause was traced back to an electrical surge that sparked a chain reaction, ultimately resulting in the explosion.

Discussion of the economic and safety implications of power surges

While the increase in voltage may be brief, the consequences can be long-lasting and severe. In this context, it is essential to understand surges’ safety and economic impacts to take appropriate measures to mitigate them.

Safety impacts

  • Power surges can cause damage to electrical equipment, leading to fires and other safety hazards.
  • Surges can cause shocks or electrocution to people in contact with electrical systems during a surge.
  • Surges can damage sensitive electronic equipment, such as medical devices, and compromise patient safety.

Economic impacts

  • Surges can cause significant damage to expensive electrical equipment, leading to costly repairs or replacements.
  • Surges can cause production downtime, leading to lost revenue for businesses.
  • Surges can result in data loss, leading to significant financial losses for businesses and individuals.

Explanation of how surge protection can mitigate these risks

Surge protection is crucial in ensuring the safety and longevity of your electrical infrastructure. Power surges, caused by lightning strikes or other electrical events, can cause severe damage to your devices and equipment. That’s why Surge Protection Devices (SPDs) are a popular solution to this challenge.

An SPD is a component of an electrical protection system designed to protect your devices from overvoltages caused by power surges. It’s like a safety valve that diverts energy from your devices and towards the ground.

These devices are connected in parallel to the power supply circuit of the loads they’re meant to protect and can be used at all levels of the power supply network. SPDs are the most commonly used and efficient type of overvoltage protection.

The SPD’s main job is to limit transient overvoltages, such as those caused by lightning or utility-initiated grid and capacitor bank switching. These surges can harm your electrical installation, switchgear, and control gear.

The SPD diverts current waves to the earth to limit the amplitude of the overvoltage to a value that’s not hazardous for your equipment.

There are three main types of SPDs, each with a specific purpose and use case in power distribution, power generation, and power transmission systems:

SPD TypePurposeUse Case
Type 1 (or Class I)Protects against direct lightning strikesUsed in high-risk areas such as power transmission systems, substations, and extensive industrial facilities.
Type 2 (or Class II)Protects against overvoltages caused by indirect lightning strikes and switching operationsUsed in low- to medium-risk areas such as power distribution systems and commercial buildings.
Type 3 (or Class III)Protects against residual overvoltages and voltage spikesUsed in low-risk areas such as residential buildings.

SPDs effectively eliminate overvoltages in common and differential modes, which means they can protect your devices from overvoltages between phase and neutral or earth and between phase and neutral.

Simply put, surge protection is like an insurance policy for your electrical infrastructure. It ensures that your devices and equipment are protected from the risks of power surges, saving you time, money, and headaches in the long run.

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Surge Protection Standards and Codes

The codes and standards section of the Electrical PE exam is crucial and typically covers about 10 questions. Questions in this section mainly focus on the National Electrical Code (NEC) and the National Electrical Safety Code (NESC).

To excel in this section, it is essential to be familiar with both codes and understand how to navigate them. Some sections of the codes are more commonly used than others, and most questions on the exam relate to those commonly used sections.

A helpful technique is memorising the code format so you know which section to look for in the book when you encounter a specific type of code question.

Below is a table outlining some of the critical surge protection codes and standards that may be covered in the PE Power exam:

NEC (National Electrical Code)A standard for the safe installation of electrical wiring and equipment in the United States.Applies to electrical wiring and equipment in buildings, structures, and premises, including public and private spaces.
NESC (National Electrical Safety Code)A standard for the safety of electric supply and communication lines and equipment.Applies to the supply and communication lines and equipment, including overhead and underground power lines.
IEEE (Institute of Electrical and Electronics Engineers)A professional association that develops technical standards for a broad range of industries.Provides standards for the design and installation of surge protection devices and equipment.
UL 1449 (Underwriters Laboratories Standard)A safety standard for surge protective devices.Applies to surge protective devices for use in low-voltage AC power circuits.
IEC (International Electrotechnical Commission)A global organization that develops and publishes international standards for all electrical, electronic, and related technologies.Provides standards for the design and installation of surge protection devices and equipment.

These codes and standards are essential for power engineers to know and understand, as they provide guidelines for the safe installation and operation of electrical systems, including surge protection.

Familiarity with these codes and standards is critical for passing the Power Engineering Electrical PE exam and ensuring electrical systems’ safety and reliability in practice.

Designing Surge Protection Systems

Designing Surge Protection Systems

Step 1: Risk Assessment

The first step in designing a surge protection system is to conduct a technical review and risk assessment of the electrical infrastructure. This assessment will provide basic protection recommendations and enable an initial design of the facility’s needs.

Step 2: Determine the Need for Protection

After conducting the risk assessment, accurate data is provided, and there are various options for surge protection resources. The requirements for protection can be categorized into the following four possibilities:

  • External protection is needed if the building structure or specified zones require protection.
  • Internal and surge protection is needed if the building or structure requires protection from electrical surges within the electrical system.
  • Both internal and external protection are needed for full protection.
  • Evaluate the need for different types of surge protection components and methodologies to address issues related to surge voltage protection, current technology surge protection, a surge of resistance, low voltage surge protection, Lightning and Surge Protection, single circuit surge protection, etc.

Step 3: Design Study

Once the need for protection is determined, it is essential to specify the level of protection required for each zone. This involves providing surge protector schematic diagrams with relevant surge protection components in different lightning protection zones and three-dimensional bonding networks required to provide shielding effects against electromagnetic interference.

All surge protection specifications must comply with industry-standard guidelines and requirements.

Step 4: Site Survey and Ground Testing

Site and ground testing are the final stages of designing a surge protection system tailored to the facility’s requirements based on efficient surge protection wiring diagrams and surge protector schematic diagrams.

This process includes all aspects of risk analysis and surge protection design to produce detailed engineering drawings and system specifications.

Smart Ground Testing is an advanced protection ground audit system that produces highly accurate results even on energized systems.

It utilizes sophisticated computer modeling, includes a complete professional analysis of IEEE/IEC standards, and provides practical recommendations to improve grounding systems and surge safety.

Step 5: Installation and Setup

After the design is finalized, the complete installation service is done with applicable warranties. There are various types of SPDs available in the market, and choosing the right one is crucial to the effectiveness of the surge protection system.

SPDs come in different types and models, each suitable for different applications, voltage levels, and current capacities. For example,

  • Type 1 SPD is suitable for outdoor installations and main electrical panels.
  • Type 2 SPDs are designed for subpanels, branch panels, and other downstream equipment.

It is essential to select the appropriate SPDs that meet the varying requirements of the electrical system.

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Surge protection is an essential aspect of power system design and operation. It helps to prevent damage to electrical infrastructure, as well as ensure safety for people and equipment.

The knowledge of codes and standards related to surge protection is crucial for power engineers seeking to obtain their PE certification and advance their careers.

Power engineers can successfully design and implement effective surge protection solutions by understanding the various types of surges, their impact on electrical systems, and the principles and applications of surge protection devices.

Additionally, having a thorough knowledge of codes and standards related to surge protection is vital for cracking the key concepts of surge protection in the PE Power Exam.


Licensed Professional Engineer in Texas (PE), Florida (PE) and Ontario (P. Eng) with consulting experience in design, commissioning and plant engineering for clients in Energy, Mining and Infrastructure.