Surge Arresters
One-Elec provides a wide choice of Schneider and Legrand Surge Protection Devices for electrical panels. Protect…
Standards and connection
A surge protection device (SPD) is connected to an electrical panel between the main circuit breaker and the differential switches. To fulfil its role, it must also be connected to a grounding outlet so the excess voltage can be safely rerouted to the ground when these lightning strikes occur. When it comes to connection, the French standard NF C 15-100 stipulates the combined length of SPD connections to the network and the earth terminal block must not exceed 50 cm. Whether it's a surge protector with or without an integrated circuit breaker, this maximum cable length must be respected by whatever type of surge protector you have to install.
The installation of a surge protection device in a home or building in France must meet the requirements of standard NF C 15-100, which is common to all professionals in the electrical sector. This standard establishes consistent practices in electrical installations, ensuring the safety of individuals and homes. It is important to consider the local standards that are in place when working on electrical installations.
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When should SPDs be installed in electrical panels?
Standard NF C 15-100, and more specifically table 44B of the amendment, sets out the rules and obligations when installing SPDs in France. The requirements when installing SPDs depend on various criteria, including the lightning density threat where the building is located and the characteristics and type of power supply to the building in question.
In France, for example, there is a classification of French departments based on their lightning strike density and Keraunic level. The lightning strike density takes into account the number of lightning strikes per year and per km². This value is identified by the index Ng. The Keraunic level corresponds to the number of thunderstorm days that occur in a year. This information is represented by the Nk index. In France, if the Keraunic level in a specific area is strictly greater than 25, then all electrical installations in that zone must be fitted with an SPD.
These two criteria are linked to the characteristics and power supply of the building. Any building fitted with a lightning rod and with a Keraunic index greater than or less than 25 must be fitted with an SPD. Similarly, if a building has a low-voltage power supply that is wholly or partially overhead and the Keraunic level is greater than 25, an SPD must be fitted in the electrical installation.
On the other hand, if a building has a low-voltage supply that is entirely or partially overhead and the Keraunic level is less than 25, then the SPD is not compulsory. The rules do not apply to a building connected underground to a low-voltage line.
Which surge protection device is recommended for specific electrical panels?
SPDs available in the one-elec online shop are designed exclusively to protect low-voltage (single or three-phase) electrical installations. The choice will depend on the type of SPD (type 1/2/3), the presumed short-circuit current of the installation and other data when an SPD is installed in the building (governed by a lightning plan).
Type 1: These SDPs are very powerful. They can discharge a very high current, usually from the earth to the power distribution network. They are found in the main electrical panel of buildings fitted with lightning rods.
Type 2: This type of SPD is installed on the main distribution board. It is used to discharge currents generated by indirect lightning strikes. This type of phenomenon generates induced or conducted over-voltages on the power distribution network.
Type 3: Type 3 SPDs have a very limited current flow capacity. Consequently, they cannot function independently and instead complement Type 2 surge protectors. Their role is to reduce overvoltages at the terminals of sensitive or critical electrical equipment. They are used in sub-panels.
Are you unable to find the right surge protector for your installation? Not sure which model to include in your electrical panel? Reach out to the One-Elec team immediately. We're happy to assist you in making the right choice.