17.2.3.5 Resume´ for lightning protection
The general recommendations for the lightning protection of structures with a risk of
fire and explosion are as follows.
1. In the case of an obvious risk to life and property, every means possible of providing
protection should be installed.
2. A single or double ground ring should be used for the lightning protection system
of each tank or vessel, interconnecting neighbouring structures.
3. It should be ensured that multiple paths exist for attaching the connecting points to
the ground system of air terminations.
4. It should be ensured that bonding is done thoroughly and that the safety distance
is observed to avoid arc flashing.
5. An isolated LPS should be installed when the lightning current flow poses a
problem to the skin of the tank or vessel, having suspended air terminals at
least 2 m apart from the structure to be protected, by using protection level I or II.
6. A non-isolated LPS should be installed when the lightning current flow does not
pose a problem to the skin of the tank or vessel, by using protection level I or II.
7. It should be ensured that the environment in the immediate vicinity of the tank of
vessel is free of gas or vapour and flametraps should be used for vents emitting
flammable vapours or powders.
8. If dangerous materials are encased in metal of adequate thickness, other than
ensuring that the bonding and grounding are sound, the additional measures
provided by systems such as air terminations may not be required at all (i.e. the
self-protecting condition is satisfied).
9. Tanks or vessels containing non-metallic materials cannot be considered to be
self-protecting.