Doubts quickly see this page where we have collected and grouped thematically the questions our customers most frequently send us.

External Protection

How it is calculated ΔT of an ESE lightning rod?

The ΔT is the early streamer emission of an ESE lightning arrester, which is obtained by a test in a high voltage laboratory. The test conditions are described in Annex C of the NF C 17-102: 2011, UNE 21186: 2011 and NP4426: 2013 standards.

What is the maximum ΔT for a lightning rod ?

According with NFC 17-102: 2011, UNE 21186: 2011 and NP4426: 2013 standards, in its point 5.2.2 and C.2.2 indicates that a lightning rod to be considered an ESE lightning rod, must obtain a ΔT at least of 10 microseconds, and the maximum permissible value of (ΔT) is 60μs, although in the test have obtained superior results.

Which is the minimum height that it has be placed an ESE lightning rod?

The tip of an ESE lightning rod should be located at least 2m above the protected area, including antennas, cooling towers, roofing, reservoirs, etc.

What it is the maximum protection radius for an ESE lightning rod?

As the maximum permissible value for ΔT following the standards is 60μs, the maximum protection radius calculated may not exceed of 120m in Level IV protection.

How to calculate whether a structure requires a lightning protection system?

Using the risk calculation indicated in the Annex A of the NFC 17-102: 2011, UNE 21186: 2011 and NP 4426: 2013.

In our website there is an WAT Franklin Plus E.S.E Lighting conductors Software Design, which is an online program that it allows to calculate the risk assessment and also make a totally free report with GOOGLE MAPS.

What are the protection levels?

The protection levels of an ESE lightning rod are the safety factors to be applied to minimize the risk of damages due lightning strikes on a structure. Protection levels for lightning protection have a range from Level I to Level IV. Being the Level I the strictest level and the level that provides a greater efficiency.

Internal Protection

Is it necessary to connect to the TV antenna to the down-conductor external lightning protection?

Yes, you must connect the metallic elements that exist on the roof the structure with the external lightning protection system to avoid creating sparks or dangerous step voltages. This electrical connection of the metal mass can be done directly, or better by a protective spark gap.

How many down-conductors needs a PDC lightning rod installation?

The NFC standards 17102: 2011, UNE 21186: 2011 and NP4426: 20131 indicate that each PDC must be connected to at least two down conductors.

Which sections and materials that can be used as down conductors?

Table of materials accepted under current regulations:

material down conductor

What is the minimum separation between down conductors?

Two downspouts are considered independent if they do not run parallel, parallel understood as a straight line distance of less than 2m between conductors.

Can you install a down conductor inside the building?

Yes, when is not possible to be done outside and the cable goes down within a specific insulating conductive and non-flammable.

Is it necessary to install a lightning counter in the lightning protection system?

The lightning counter installation is necessary to know when the installation has received the lightning strike and thus perform the verification of lightning rods and grounding.

You only need to install a lightning counter for installation regardless of the number of down-conductors to earth disposal, the equipment also account for the impact of lightning on the system.

It can be used a metal structure as the current shunt element of a lightning?

Yes, the exterior steel trusses interconnected (metal structures) can be used as natural drainpipes of external protection systems against lightning, provided that its conductivity is ensured and its impedance is less than or equal to 0.01 Ω.

What is a spark gap?

A spark gap or ISG isolation (isolating spark gap) is 2 electrodes spaced a certain distance, in order to electrically insulate conductive installation sections. If lightning strikes the plant sections are temporarily connected as a result of response to discharge.


Can you connect the lightning protection grounding to the grounding of low voltage in a building?

Yes, it is recommended to connect the two grounding systems to achieve an equipotential system throughout the facility.

Current standard indicates that "When the building or the protected volume has a foundation earth termination system for low voltage, the ESE earth termination systems should be connected to it with a standardised conductor (see EN 50164-2)."

What is the value for a grounding system in an installation of lightning protection?

For ESE lightning rod installations, the maximum resistance value is 10 ohms.


How storms detected?

Different devices for detecting storm and lightning detection, being the most commonly used technologies:

1. Electrostatic field meter. The field mill indicates the real-time measurement of the value of electrostatic field (V / m), this device is programmed to send alarms when there is risk of lightning strike. It allows us to know the evolution of the storm and make preventive measures before the first lightning strikes.

2. Electromagnetic pulse detectors. By installing multiple antennas, the exact location of the lightning strike is obtained. This information allows you to create predictive models to know which direction the storm can take to complete the necessary prevention measures.

Regulations of the storm detectors

UNE EN 50536: 2011 (Protection against lightning - Thunderstorm warning systems) explains how must be a correct prevention against lightning and determines the different existing detection systems. Is coming so to approve the IEC 62793 is the international version of the European 50536.

Preventive measures in case of imminent risk of lightning strike.

The measures taken are different depending on the type of installation and / or equipment that we have. Highlights include:

For the protection of living beings, in case of risk of lightning strikes in open areas, schools, sports facilities, amusement parks, golf courses, etc ... it is recommended to evacuate people in the exposed areas.

Industry should be disconnected from external power surges sensitive so that they are protected in case of falling on power lines ray equipment.

Surge protection

What is internal lightning protection?

They are the appropriate protection to avoid the surge in the power supply system, communications or data system.

What is a surge?

It’s an over voltage with a big magnitude, about tens of kV and with a short duration (microseconds). However, they have a highly destructive power on sensitive electronic equipment.

How surges originate?

They arise mainly as a result of lightning strikes, switching in the networks and/or defects therein.

What are the most common causes of occurrence of surges from atmospheric origin?

The lightning strikes in the distribution lines or close to, or the lightning strikes in external protection system located in the same building or nearby.

What regulations apply to protect against surges?

There are different rules and regulations, the most important are the RBT (ITC-BT-23), EN 61643-11: 2012, IEC 62305-4.

How can we protect ourselves from surges?

The SPD (surge protection devices), are intended to reduce the input surge to a lower value. This is accomplished with a strategy that integrates 3 protection levels: type 1, type 2 and type 3. Thereby achieving a low voltage level not dangerous for the electronic equipment.