Surge Protection Devices operate according to the luminaries' protection class.
In Class I, the SPD enhances protection of the driver between phase and neuter. Between neuter and ground, the SPD and a gas discharger suppress surcharges between the poles and ground, maintaining the voltage difference at around 2000V. A high-current 16A fuse is recommended in case of short-circuits. VPA1500KK1 and KK2 contain a thermal protection to interrupt the charge in case of damage to the varistor.
In Class II, surcharges cannot be sent to ground. Protections are more limited and operate either at input or at LED plate supply point. At input, the SPD enhances potection of the driver against overvoltages. At secondary site, PR4DS, PR8DS, RPR4DS create an equipotential point in case of unavailability of connection to the equipotential. VPR4DS1 also provides primary potection.
 Second class installations (the driver and LED plate are isolated from the armature. The armature does not go to ground)
In this case it is not possible to ground the discharges which, on the line, occur between phase and earth and between neutral and earth. The protections are more limited and operate separately between the driver input and the power supply of the LED plate
Driver Input A suppressor (varistor) raises the driver's own protection level and provides additional surge immunity.
Secondary protection In the second class configuration it is necessary to connect the LED plate to the frame of the armature through a capacitive impedance to limit the overvoltage between the plate itself and the armature. Many drivers offer it as standard (connection to equipotential). If there is no or if a symmetrical connection is desired, the device PR4DS, PR8DS (double channel) RPR4DS (capacitors + resistor) create an equipotential point. The VPR4DS1 protection, in addition to creating an equipotential point, provides primary protection.
Complete PDF datasheet