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Section 10
9
Installing surge arresters in
a box or cabinet
General installation
rules
Rule 2
The outgoing feeders of the protected conductors must be connected right at the
terminals of the surge arrester and disconnection circuit-breaker (fig. 37).
Fig. 37 - the connections are right at the surge arrester's terminals.
Rule 3
The phase, neutral and PE incoming wires must be tightly coupled to reduce the
loop surfaces (fig. 38).
Rule 4
The surge arrester's incoming wires must be moved away from the outgoing wires
to avoid mixing the polluted cables with the protected cables (fig. 38).
Fig. 38 - example of wiring precautions to be taken in a box (rules 2,3,4,5)
Rule 5
The cables must be flattened against the metallic frames of the box in order to
minimise the frame loops and thus benefit from a disturbance screening effect.
If the box is made of plastic and the loads particularly sensitive, it must be replaced
by a metal box.
In all cases, you must check that the metallic frames of the boxes or cabinets are
frame grounded by very short connections.
Finally, if screened cables are used, extra lengths which serve no purpose
("pigtails"), must be cut off as they reduce screening effectiveness.