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Total Solution to Earthing & Lightning Protection |
9AKK106354A3360
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Furse earthing conductors form an integral part of the single
earthing arrangement for a structure, whether they provide
the means of connection to the final earth electrode (earth rod
or plate), or whether they comprise the earth electrode itself
(through an earth grid or ring earth arrangement).
An earth conductor must be capable of carrying the maximum
expected earth fault current and leakage current likely to
occur at a structure. The size or minimum cross-sectional
area of the conductor must therefore be gauged in
accordance with these criteria.
A good earth conductor must also:
–– Be able to withstand mechanical damage
–– Be compatible with the material of the earth electrode
–– Resist the corrosive effect of local soil conditions
Furse conductors effectively meet these requirements and are
available in a range of sizes to meet differing current ratings
(see table left). Copper conductor is recommended as,
following BS 7430, aluminium should not be installed in
contact with soil, nor in damp areas, and it should not be
used to make the final connection to an earth electrode.
Conductors for earthing systems
For below ground earthing applications we offer a large range
of bare copper tape, solid circular and stranded conductors
thus offering the designer of the system the correctly rated
conductor without the need to oversize.
Conductor Size C.S.A.
(mm)
(mm
2
)
kA for 1 Sec kA for 3 Sec
12.5 x 1.5
18.75
3.3
1.9
12.5 x 3
37.5
6.6
3.8
20 x 1.5
30
5.3
3.0
20 x 3
60
10.6
6.1
25 x 1.5
37.5
6.6
3.8
25 x 3
75
13.2
7.6
25 x 2
50
8.8
5.1
25 x 4
100
17.6
10.2
25 x 6
150
26.4
15.2
30 x 2
60
10.6
6.1
30 x 3
90
15.8
9.1
30 x 4
120
21.1
12.2
30 x 5
150
26.4
15.2
31 x 3
93
16.4
9.5
31.5 x 4
126
22.2
12.8
31 x 6
186
32.7
18.9
38 x 3
114
20.1
11.6
38 x 5
190
33.4
19.3
38 x 6
228
40.1
23.2
40 x 3
120
21.1
12.2
40 x 4
160
28.2
16.3
40 x 5
200
35.2
20.3
40 x 6
240
42.2
24.4
40 x 6.3
252
44.4
25.6
50 x 3
150
26.4
15.2
50 x 4
200
35.2
20.3
50 x 5
250
44.0
25.4
50 x 6
300
52.8
30.5
50 x 6.3
315
55.4
32.0
50 x 7
350
61.6
35.5
50 x 8
400
70.4
40.6
50 x 10
500
88
50.8
60 x 10
600
105.6
61
80 x 6
480
84.4
48.8
100 x 6
600
105.6
61
These conductor ratings are based upon the recommendations of BS 7430 with an
initial conductor temperature of 30°C and a maximum temperature of 250°C