Surge Protective Device (SPD): Also known as a surge protector, over-voltage protector, or commonly referred to as a lightning arrester or surge arrester. It is primarily used to protect electrical devices from damage caused by lightning-induced electromagnetic pulses or operational over-voltages. It limits transient over-voltages that surge into power lines or signal transmission lines to a voltage level that the equipment or system can handle, or diverts powerful lightning currents to the ground, thus protecting the equipment or system from damage due to such surges.

SPD-specific Disconnector (SSD): An external disconnector installed in series with the surge protective device (SPD) in low-voltage power systems, also known as a pre-SPD external disconnector. It is commonly referred to as the SPD-specific backup protection device. Its main functions are as follows:

1. Protection Against Short-Circuit: When an abnormal transient over-voltage causes the SPD to conduct and leads to a short circuit, this can result in a power outage or even a severe fire hazard. The SSD is designed to quickly disconnect the circuit if a short circuit occurs in the SPD. It is crucial that this external disconnector has the capability to interrupt the short-circuit current; otherwise, it may lead to arcing and severe fire risks.
2. Protection Against SPD Deterioration: If the SPD deteriorates due to lightning strikes or transient over-voltage impacts, and its breakdown voltage drops below the supply voltage, the power frequency leakage current may rapidly increase. When this current is only a few amperes, the SPD's thermal trip mechanism can disconnect the circuit. However, if the current exceeds 10A, the SPD may overheat and catch fire faster than heat can be transferred to the trip mechanism. Thus, the SSD must disconnect the circuit before the SPD catches fire to prevent fire hazards.
3. Avoiding False Tripping: The SSD ensures that the SPD's effectiveness in protecting electrical equipment from lightning is maintained. It prevents false tripping, ensuring that the lightning protection remains operational at all times.

This section covers the general principles to be followed in the protection of buildings, living creatures and installations in and around the building from lightning.

Where lightning can fall on a structure and how the impact can cause damage and losses are specified in the standard.
Accordingly, four main damage sources are defined for the Damages and Losses that may occur.
These are;
(S1) Lightning striking the structure,
(S2) Lightning striking near the building,
(S3) Lightning striking a service installation connected to the building,
(S4) Lightning strike next to a service installation connected to the building,

Also, as indicated in the table, each source of damage may have impacts that may result in at least one (or more) of the three damage / losses listed below.
These;
(D1) Injury of living things due to step and contact voltages,
(D2) Physical damage due to lightning current effects caused by spark (fire, explosion, mechanical destruction, chemical release),
(D3) is the failure of internal systems due to Lightning Electromagnetic Pulse (LEMP).

NOTE: Table: Damages and losses in a structure of lightning strike

Within the scope of this information, with the effects of lightning strike;
(L1) Loss of human life,
(L2) Loss of service to the public,
(L3) Loss of cultural heritage and,
(L4) Damage / loss situations may occur with consequences such as the loss of economic values.

In order to protect a structure from lightning current and the electromagnetic field effects created by this current, it is necessary to enclose a well-grounded, thick metal shield that can hold the magnetic flux. However, such a situation is almost impossible in practice.

Lightning Protection Zones (LPZ):
When preparing a lightning protection project, firstly, Lightning Protection Zones (Ligtning Protection Zone (LPZ) and Separation Distances should be determined for a viable project.

Lightning Protection Zones (LPZ) are defined in TS EN 62305 Standard to create protection measures against the negative effects of lightning strikes for a building / facility. According to this;
(LPZ 0A), Outside the building / facility and areas with direct lightning risk,
(LPZ 0B), Areas outside the building / facility and with partial lightning risk / intense magnetic flux risk,
(LPZ 1 and LPZ 2), Areas with no direct lightning risk / partial risk of magnetic flux within the structure / facility and,
(LPZ 2 and LPZ 3) are defined as areas with no direct lightning risk / little or no magnetic flux risk within the structure / facility.

Lightning Protection Levels (LPL):

Four different lightning protection levels are defined in the TS EN 62305 Standard according to the structural and environmental factors of the building / facility. These are;
Level I (LPL-I),
Level II (LPL-II),
Level III (LPL-III),
Level IV (LPL-IV). And, A set of maximum and minimum lightning current parameters is assigned for each lightning protection level.
Lightning Protection Measures:

The Lightning Protection System should always be planned to eliminate or reduce the risk that may occur due to lightning strike and / or magnetic effects. In this context;

A. Major measures to be implemented to reduce injury to living things due to contact and step stresses;
1. The exposed conductive parts must be insulated sufficiently,
2. An equipotential network should be created by connecting the grounding system of the building / facility,
3. Measures should be taken by using physical restrictions and warning signs.
Notes:
I. Equipotentialization is not effective against contact voltages.
II. Increasing the surface resistance of the ground inside and outside the structure can reduce the risk of death.

B. Measures to be implemented to reduce physical damage;
1. For structures: Lightning protection system (Ligtning Protection System) (LPS) should be planned,
Notes:
I. Equipotentialization is an essential precaution to reduce fire and explosion hazard and death hazard when installing an LPS.
II. Measures that limit the development and spread of fire, such as fire-resistant compartments, extinguishers, fire hydrants, fire alarm and extinguishing facilities, can reduce physical damage.
III. Protected escape routes provide protection for personnel.
IV. Metal ducts provide very effective protection for buried cables.
2. For service installations: Shielding conductor / wire should be used.

C. Measures to be implemented to reduce the malfunctions of electrical and electronic systems;
1. For Structures: Protection measures from Lightning Electromagnetic Power (LEMP) should be taken, accordingly;
(I).Grounding and connection provision measures should be taken,
(II). Magnetic shielding should be done,
(III). Route should be selected correctly,
(IV).Protection of Surge Protection Devices (SPD) should be planned with the correct coordinated project,
2. For service installations:
(I).Surge arresters (SPD) should be used at different locations along the 1st line and at the end of the line,
(II). Magnetic screening should be done for the cables.

Notes:
I. Continuous metal screen of sufficient thickness for buried cables provides a very effective protection.
II. Route backup, device backup, stand-alone generators, uninterruptible power supplies, liquid storage systems and automatic fault detection systems are very effective protection measures to reduce the loss of service activity.
III. The high withstand voltages of the insulation of the devices and cables are a very effective protection measure against failures caused by overvoltages.

Selection of Lightning Protection Measures:
In order to choose the protection measure in the building / facility, the technical and economic aspects of different protection measures should be carefully evaluated and the most appropriate Lightning Protection System should be designed for the building / facility in terms of cost-benefit.
Criteria for risk assessment and selection of the most appropriate protection measures are given in TS EN 62305-2.
In order for the protection measures to be effective, they must comply with the relevant standards and be able to withstand the expected stresses where they will be installed.

STAGE 2 - RISK MANAGEMENT:

EN 62305-2 Risk Management:

This section is a guide for the correct implementation of the 3rd and 4th sections of the Standard and includes a risk assessment at the project design stage of the Lightning Protection System (LPS) and the definition of the Level of Lightning Protection System (LPL) within the scope of the result obtained.

The main purpose of risk assessment is to identify the relevant main / primary risks and reduce them when necessary. For this, the risk algorithm / map is created first.
TS EN 62305-2 Standard collects the types of losses that pose a risk under four main headings. These;
1. (R1) Risk of losing human life
2. (R2) Risk of loss of service to the public
3. (R3) Risk of loss of cultural heritage
4. (R4) Risk of economic value loss.

At the stage of creating the risk algorithm;

A. When evaluating the first three basic / primary risks (R1) (R2) (R3), firstly a Tolerable Risk value (RT) is determined for each risk.
Then the Real Risk (Rn) value is found. The true risk value is equal to the sum of the risk components (Rx).
(ΣRx = Rx1 + Rx2 + …… .. + RxX). ΣRx = Rn
At the end of all this evaluation;
If the Real Risk (Rn) is equal to or lower than the Tolerable Risk (RT), protection measures may not be taken. If . If the actual risk (Rn) is greater than the corresponding tolerable risk (RT), protection measures should be taken. After each measure, the Risk Algorithm / Map is re-evaluated.
This process is repeated until Rn is equal to or less than RT (Rn≤RT).

B. When evaluating the fourth principal / primary risk (R4), loss costs are evaluated first.
According to this;
CRL: Cost of loss when there are protection measures,
CPM: The cost of safeguards,
CL: Loss costs are determined in the absence of safeguards.

At the end of these determinations;
If CRL + CPM

A lightning protection system is designed for any structure that may be struck by lightning. Whether it’s a residential, commercial, or industrial building, all are at risk of lightning strikes. The need for a lightning protection system depends on factors like the height of the building, the frequency of lightning activity in the area, and the building's function. High-rise buildings, critical public buildings, hospitals, and data centers often require more stringent lightning protection, while low-rise residential buildings in areas with less frequent lightning may require only basic protection.

The depth of the grounding system depends on the soil’s resistivity. Soil with higher resistivity (like dry sandy soil) will require deeper grounding electrodes, while soil with lower resistivity (such as wet clay) can have shallower electrodes. Generally, the grounding resistance should be less than 10 ohms. In poor soil conditions, additional electrodes or a greater depth might be necessary. When designing the system, factors such as local soil resistivity and the building's requirements must be considered.

Yes, the lightning protection system should be inspected and maintained regularly. Inspections should include:

• Ground resistance checks to ensure the resistance remains within acceptable limits (typically less than 10 ohms).
• Inspection of grounding electrodes for corrosion or damage.
• Checking conductor connections to ensure they are secure and free of corrosion.
• Inspecting surge protection devices (SPDs) for functionality. A thorough inspection is generally recommended annually to ensure the system remains effective.

To protect internal electrical equipment from lightning strikes or electromagnetic pulses (LEMP) caused by lightning, Surge Protection Devices (SPDs) should be installed. SPDs should be placed at power entry points and along critical lines. Additional measures include:

• Grounding all electrical equipment to ensure lightning currents are safely diverted into the ground.
• Electromagnetic shielding for sensitive equipment.
• Proper routing of cables to avoid interference.
• Using backup systems such as uninterruptible power supplies (UPS) and generators to maintain service in the event of a lightning-related power failure.

• The lightning protection grounding system is different from the electrical grounding system. The lightning protection grounding system is specifically designed to safely direct lightning current into the earth, preventing damage to the building's structure and equipment. In contrast, the electrical grounding system is designed to protect electrical equipment from faults and prevent electrical hazards. While they serve different purposes, both systems may share grounding electrodes, and both must meet specific standards for safety.

• The main objective of interior lightning protection is to safeguard electrical equipment from lightning or LEMP effects. Key measures include:
• Surge Protection Devices (SPDs) installed at entry points and critical internal systems.
• Grounding all electrical systems to prevent the passage of lightning currents through equipment.
• Electromagnetic shielding for sensitive devices.
• Proper cable management to avoid potential hazards from lightning currents.
• Backup systems like UPS and generators to ensure continuity of service during power outages.

• The design of a lightning protection system should take into account:
• Building height: Tall buildings are more likely to be struck by lightning and require more robust protection.
• Building function: Critical buildings such as hospitals or data centers need higher levels of protection.
• Lightning activity in the area: Areas with frequent lightning strikes require more stringent protection measures.
• Soil resistivity: The type of soil affects the grounding system's design.
• Sensitive equipment: Buildings with sensitive equipment (like computers and communication systems) should include additional protection such as SPDs and shielding.

• Yes, lightning can significantly affect communication systems by generating electromagnetic pulses (LEMP) that disrupt signal transmission and damage equipment. To protect communication systems from lightning:
• Install Surge Protection Devices (SPDs) at key points along the communication lines.
• Shielding cables from electromagnetic interference caused by lightning.
• Proper grounding to direct lightning currents safely to the ground.
• Using dedicated lightning-resistant cables and protective measures to ensure the system's integrity.