1. The Voltage Grade to be taken into consideration for single-core cable used in series lighting circuits is the continuous AC working voltage between core and earth. A 5 kV FL2XSYRY cable can operate continuously and safely at an AC potential of 5000V to earth.
2. On the contrary, other National Standards define voltage grades differently, which can be misleading when comparing characteristics and performances of airport lighting cables. For example: - VDE 0271, ‘.The German Standard applicable to PVC- Insulated core rates the FLYCY airfield lighting cables as 3.0/6.0kV or 5.0/10.0 kV. The first figure (U0) represents the working voltage to earth, the second figure (U) the working voltage of a single-phase, multiple circuit made of two single- core FLYCY cables. According to correct electrical practice this cable (3.0/6.0kV) is in fact a 3 kV cable. The same applies to the FLYCY 5.0/10.0 kV which corresponds to a 5kV FL2XSYRY cable.
3. British Standards (BSI) rate the airport lighting cables as 1.9/3.3 kV. This corresponds to a working voltage to earth of 1.9kV, while 3.3kV may be applied between the cores of a three-phase distribution system made of 3 each single-core airport lighting cables.