Non-compliance with the separation distance can lead to sparkover from the conductors of the external lightning protection system to electrical and metal installations inside of the building or structure.
Nevertheless electrical separation in the external lightning protection often is deemphasized. Therefore the air-termination system meshes of the external lightning protection system e.g. on extended facilities such as logistics centres, high-bay warehouses or production buildings are not installed with the necessary separation distance to metal components and electrical systems lying underneath.

For an easy and practical realization of the electrical separation in external lightning protection, the roof conductor holders DEHNiso RCH have been developed. They comprise a glass-fibre reinforced plastic bar (GRP) with plastic conductor holder and a concrete block with support plate.

Distance between the roof conductor holders (mid to mid of GRP bar) is max. 1.2 m each.

The roof conductor holders are dimensioned for wind velocities up to 145 km/h and 162 km/h (wind load zone II + III), provided that the specified distance of ≤ 1.2 m is complied with.
This system is compatible with GRP/Al air-termination rods, if protected zones are needed e.g. for roof superstructures.

Spacer bar made of glass-fibre reinforced plastic (GRP) Ø10 mm, UV stabilized, light grey colour

Material factor km = 0.7 is applied to determine the separation distance (length of spacer bar).
The insulating clearance of 220 / 360 mm thus is equal to a separation distance of 150 / 250 mm (in air) or 300 / 500 mm (solid material).