72 Electrical installation
360-degree grounding
When the outer surface of the shield is covered with non-conductive material:
1. Strip the cable carefully (do not cut the grounding wire and the shield).
2. Turn the shield inside out to expose the conductive surface.
3. Wrap the grounding wire around the conductive surface.
4. Slide a conductive clamp onto the conductive part.
5. Attach the clamp to the grounding plate with a screw as close as possible to the
terminals where the wires are about to be connected.
Connecting the shield wires
Single-shielded cables: Twist the grounding wires of the outer shield and connect
them through the shortest possible route to the nearest grounding hole with a cable
lug and a screw.
Double-shielded cables
: Connect each pair cable shield (twisted grounding wires)
with other pair cable shields of the same cable to the nearest grounding hole with a
cable lug and a screw.
Do not connect shields of different cables to the same cable lug and grounding
screw.
Leave the other end of the shield unconnected or ground it indirectly via a few
nanofarads high-frequency capacitor (for example, 3.3 nF / 630 V). The shield can
also be grounded directly at both ends if they are
in the same ground line
with no
significant voltage drop between the end points.
Keep the signal wire pairs twisted as close to the terminals as possible. Twisting the
wire with its return wire reduces disturbances caused by inductive coupling.
1
2
3
4
Insulation
Double-shielded cable
Single-shielded cable
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