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Cable Terminations & Minimum Air Clearances for Bushings

Published 11 May 2021

Cable Terminations & Minimum Air Clearances for Bushings

  • Check the cable box for minimum clearances and refer to table 1 below.
  • If actual dimension ‘A’ and ‘B’ is less than the value given, a bushing boot must be fitted.
Table 1 – Minimum Air Clearances for Terminations in Cable Boxes in Accordance with BS 164 Class A.
Maximum System Voltage, Phase to Phase (kV) 7.2 12 24 36
Minimum Air Clearance Between Live Metal ‘A’ (mm) 90 127 242 356
Minimum Air Clearance Between Live Metal and Earth ‘B’ (mm) 65 75 140 222

 

Table 2 – Minimum Air Clearances for Terminations in Cable Boxes in Accordance with BS 164 Class A. with Bushing Boots Fitted
Maximum System Voltage, Phase to Phase (kV) 7.2 12 24 36
Minimum Air Clearance Between Live Metal ‘A’ (mm) 45 75 100 125
Minimum Air Clearance Between Live Metal and Earth ‘B’ (mm) 32 60 75 100

 

Table 3 – Minimum Clearance Between Cores and Between Cores and Earth
Maximum System Voltage, Phase to Phase (kV) 7.2 12 24 36
Minimum Clearance ‘C’ (mm) Measured From top of Stress Tubes 15 20 40 50

 

Table 4 – Minimum Clearance Between top of The Stress Control Tubing and Base of the Cable Lug.
Maximum System Voltage, Phase to Phase (kV) 7.2 12 24 36
Minimum Clearance ‘D’ (mm) 30 50 95 250

 

Table 5 – Impulse Voltage Withstand for Indoor Terminations, Installed With Bushing Boots, on Bushings in Accordance with BS2562.
Maximum System Voltage, Phase to Phase (kV) 7.2 12 24 36
Impulse Withstand Voltage (kV) 75 95 125 170
MV HV Cables 11kV 33kV

MV HV Cables 11kV 33kV – Joints, Terminations & Connections

THORNE & DERRICK

Thorne & Derrick are national distributors of LV, MV & HV Cable Installation, Jointing, Substation & Electrical Equipment – servicing businesses involved in cabling, jointing, substation, earthing, overhead line and electrical construction at LV, 11kV, 33kV, 66kV and EHV. Supplying a complete range of power cable accessories to support the installation and maintenance of low/medium and high voltage power systems:

  • Slip-on Cable Terminations
  • Cold-shrink Cable Terminations
  • Heat-shrink Cable Terminations
  • Cable Joints – Heat & Cold-shrink
  • Separable Connectors (Euromold)
  • Surge Arresters & Switchgear/Transformer Bushings

Key Product Categories: Duct Seals | Cable Cleats | Cable Glands | Electrical Safety | Arc Flash Protection | Cable Jointing Tools | Cable Pulling | Earthing | Feeder Pillars | Cable Joints LV | Joints & Terminations MV 

Thorne & Derrick International

 

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