132 kV overhead lines: electric fields

132 kV overhead lines are usually carried on lattice steel pylons, but smaller than used for 275 kV and 400 kV lines.  Sometimes they are carried on wood poles.

The maximum field is produced by the largest design of line – the L7 – when the ground clearance is the minimum allowed – 7.0 m.  The field also depends on the phasing. 132 kV lines usually have Untransposed (U) phasing.

graph showing maximum field

Typical fields are lower than the maximum field because the clearance is usually higher.  The three curves shown here are for the normal U phasing, and three different line designs: L7 (the highest), a smaller pylon design, the L132, and a wood-pole design (the lowest field).

graph showing typical field

132 kV pylon:   132 kV wood pole:
photo of 132 kV pylon photo of 132 kV wood pole

This table gives some actual field values for the same conditions.

 

electric field in V m-1 at distance from centreline

maximum under line

10 m

25 m

50 m

100 m

132 kV

largest lines

L7

twin bundles

0.305 m

lynx

maximum

clearance 7 m
phasing U

3615

913

182

81

23

typical

clearance 10 m
phasing U

2372

890

103

72

23

smaller lines

L132

single conductors

0.4 sq in

maximum

clearance 7 m
phasing U

2628

697

154

66

19

typical

clearance 10 m
phasing U

1780

689

86

59

18

smallest wood-pole design

trident

150 m span

single conductors

lynx

maximum

clearance 7 m
single circuit

1174

588

73

11

2

typical

clearance 10 m
single circuit

583

458

89

15

3

Note:

1. All fields calculated at 1 m above ground level.

2. All electric fields are calculated for the nominal voltage.  In practice, voltages (and hence fields) may rise by a few percent.

3. All electric fields calculated here are unperturbed values.

4. All fields are given to the same resolution for simplicity of presentation (1 V/m) but are not accurate to better than a few percent.

5. Calculations ignore zero-sequence voltages.  This means values at larger distances are probably underestimates, but this is unlikely to amount to more than a few percent and less closer to the line.

6. The “maximum field under the line” is the largest field, which is not necessarily on the route centreline; it is often under one of the conductor bundles.

7. Sometimes, a 132 kV circuit could be carried on a line designed for 275 kV or 400 kV.  Then the electric fields could be larger than shown here.

For comparison of fields from different voltage lines click here:

link to page of comparisons

For more fields at this voltage and fields at other specific voltages see this index:

link to page of specific power lines