16
•
Connecting leads that are run inside buildings shall be effectively insulated from the earthed structural parts
of the building. This may be achieved by using insulated high voltage cable.
•
Connecting leads that are run underground shall be run in conduit of insulating material or else insulated
high voltage cable shall be used. Care must be taken to avoid damage to the connecting leads due to the
effects of vehicle wheels sinking into the ground.
•
Connecting leads shall not be installed in the same conduit as the mains supply wiring, communication
cables or data cables.
•
Connecting leads and electric security fence wires shall not cross above overhead power or communication
lines.
•
Crossings with overhead power lines shall be avoided wherever possible. If such a crossing cannot be
avoided it shall be made underneath the power line and as nearly as possible at right angles to it.
•
If connecting leads and electric security fence wires are installed near an overhead power line, the
clearances shall not be less than those shown in the table below.
Minimum clearances from power lines for electric security fences
Power line voltage (V)
Clearance (m)
≤
1 000
>1 000 and
≤
33 000
>33 000
3
4
8
•
If connecting leads and electric security fence wires are installed near an overhead power line, their height
above the ground shall not exceed 3 m
•
This height applies to either side of the orthogonal projection of the outermost conductors of the power
line on the ground surface, for a distance of:
- 2 m for power lines operating at a nominal voltage not exceeding 1 000 V
- 15 m for power lines operating at a nominal voltage exceeding 1 000 V.
•
A spacing of 2.5 m shall be maintained between uninsulated electric security fence conductors or
uninsulated connecting leads supplied from separate energizers. This spacing may be less where conductors
or connecting leads are covered by insulating sleeving, or consist of insulated cables rated to at least 10 kV.
•
This requirement need not apply where the separately energized conductors are separated by a physical
barrier that does not have any openings greater than 50 mm.
•
A vertical separation of not less than 2 m shall be maintained between pulsed conductors fed from separate
energizers.
•
Electric security fences shall be identified by prominently placed warning signs.
•
The warning signs shall be legible from the secure area and the public access area.
•
Each side of the electric security fence shall have at least one warning sign.
•
Warning signs shall be placed:
- at each gate;
- at each access point;
- at intervals not exceeding 10 m;
- adjacent to each sign relating to chemical hazards for the information of the emergency services.
•
Any part of an electric security fence that is installed along a public road or pathway shall be identified at
frequent intervals by warning signs securely fastened to the fence posts or firmly clamped to the fence
wires.
•
The size of the warning sign shall be at least 100 mm × 200 mm.
•
The background colour of both sides of the warning sign shall be yellow. The inscription on the sign shall
be black and shall be either:
- the symbol of Figure 1, or
- the substance of “CAUTION: Electric security fence”.
•
The inscription shall be indelible, inscribed on both sides of the warning sign and have a height of at least
25 mm.
