534 – Devices for protection against overvoltage

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This section focuses mainly on the requirements for the selection and erection of SPDs for protection against transient overvoltages and with the protection against the effects of direct lightning strokes or strokes near to the supply system.

FIG 534.1 – LIGHTNING PROTECTION ZONES (LPZ)

534.4.1.1 – Where SPDs are required:

  1. SPDs installed at the origin of the electrical installation shall be Type 1 or Type 2
  2. SPDs installed close to sensitive equipment to further protect against switching transients originating within the building shall be Type 2 or Type 3

FIG 534.2 EXAMPLES OF INSTALLATION OF TYPE 1, TYPE 2 AND TYP3 SPDS

534.4.3.1 – Connection Type CT1

Connection Type CT1 (e.g. 4+0 configuration): – SPD assembly providing a mode of protection between each live conductor (line and neutral conductors, if available) and PE.

534.4.3.2 – Connection Type CT1

Connection Type CT2 (e.g. 3+1-configuration): – SPD assembly providing a mode of protection between each line conductor and the neutral conductor, and between the neutral conductor and PE

TABLE 534.5 – CONNECTION OF THE SPD DEPENDENT ON SUPPLY SYSTEM

Supply system at the connection point of the SPD assembly Connection Type
CT1 CT2
TN system Y Y
TT system SPD only downstream of RCD Y
IT system with neutral Y Y
IT system without neutral Y N/A

 


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