311 / 336
Total Solution to Earthing & Lightning Protection |
9AKK106354A3360
16/13
16
Figure 11. Typical methods of bonding to steel reinforcement within concrete
Natural components
IEC/BS EN 62305 encourages the use of fortuitous metal
parts on or within the structure to be incorporated into
the LPS. That these are welded, clamped with suitable
connection components or overlapped a minimum of 20 times
the rebar diameter. This is to ensure that those reinforcing
bars likely to carry lightning currents have secure connections
from one length to the next.
When internal reinforcing bars are required to be connected
to external down conductors or earthing network either of
the arrangements shown in Figure 6 is suitable. If the
connection from the bonding conductor to the rebar is to be
encased in concrete then the standard recommends that
two clamps are used, one connected to one length of rebar
and the other to a different length of rebar. The joints
should then be encased by a moisture inhibiting compound
such as Denso tape.
If the reinforcing bars (or structural steel frames) are to be
used as down conductors then electrical continuity should be
ascertained from the air termination system to the earthing
system. For new build structures this can be decided at
the early construction stage by using dedicated reinforcing
bars or alternatively to run a dedicated copper conductor
from the top of the structure to the foundation prior to
the pouring of the concrete. This dedicated copper
conductor should be bonded to the adjoining/adjacent
reinforcing bars periodically.
If there is doubt as to the route and continuity of the
reinforcing bars within existing structures then an external
down conductor system should be installed. These should
ideally be bonded into the reinforcing network of the
structures at the top and bottom of the structure.
Stranded copper cable
(70 mm
2
PVC insulated)
Cast in
non-ferrous
bonding
point
Bonding conductor
Clamped cable to rebar
connection
Steel reinforcement within
concrete (rebar)