Earthing System Test Form / Document Number: ECP 11-0406
Version: 1.0
Date: 23/03/2015

Earthing System Test Form

(completerelevant sections – testing should be non-invasive without any disconnections)

Substation Name
Substation Number
Earthing Layout Drawing Number
Earthing Design Report Number
Earth Resistance Measurement
Measure overall earth resistance using fall-of-potential measurement / Ω
Site Assessment (note any defects on comments page) / (or n/a)
Carry out an initial visual inspection
Check visually for any obvious infringement of safety clearances
Earthing Drawing Mark-up (note any defects on comments page) / (or n/a)
Locate earthing drawing (or site layout if no earthing drawing exists)
Check/update the earthing drawing (tracing the electrode where required and noting any inconclusive results) / Main perimeter electrode inside/outside (mesh design) or main spines (radial design)
Main cross-conductors
Equipment connections
Connections to terminal towers
Earth mats
Earth test pits
Above-ground earthing conductors
Check for electrodes around the outside of the fence or radial electrodes running perpendicularly out from the fence
Check for signs or corrosion or damage
Check for insufficient electrode depth
Joints (note any defects on comments page) / ( or n/a)
Copper to Copper / Check joints for signs of decay, corrosion, overheating or damage
Check joint is either brazed or exothermically welded
Copper to Aluminium / Check joints for signs of decay, corrosion, overheating or damage
Check joint is 150mm above ground level
Check joint is protected from moisture ingress
Check for non-approved joints (rivets, cold pressure welds etc.)
Joint Resistance Measurements
Measure resistance of key exposed accessible joints using a micro-ohmmeter and record below
Location / Resistance / Location / Resistance
µΩ / µΩ
µΩ / µΩ
µΩ / µΩ
µΩ / µΩ
µΩ / µΩ
Transformer / No of Tank Earths / Tap Changer Earth / Cables Boxes Earth / Cooler Earth / Double Bolted / Corrosion or Damage
YES / NO / YES / NO / YES / NO / YES / NO / YES / NO
YES / NO / YES / NO / YES / NO / YES / NO / YES / NO
YES / NO / YES / NO / YES / NO / YES / NO / YES / NO
YES / NO / YES / NO / YES / NO / YES / NO / YES / NO
Transformer Neutral / Neutral Earth / Impedance / Fault Current Magnitude / Corrosion or Damage
SOLID / NER / NEX / ASC / Ω / A / YES / NO
SOLID / NER / NEX / ASC / Ω / A / YES / NO
SOLID / NER / NEX / ASC / Ω / A / YES / NO
SOLID / NER / NEX / ASC / Ω / A / YES / NO
CVT / Structure Earth / Double Bolted / HF Earth Rod inc Resistance / HF Earth Rod Connected to Earth Grid / HF Down-lead (Straight/Bends) / Corrosion or Damage
YES / NO / YES / NO / YES / NO / Ω / YES / NO / S / B / YES / NO
YES / NO / YES / NO / YES / NO / Ω / YES / NO / S / B / YES / NO
YES / NO / YES / NO / YES / NO / Ω / YES / NO / S / B / YES / NO
YES / NO / YES / NO / YES / NO / Ω / YES / NO / S / B / YES / NO
YES / NO / YES / NO / YES / NO / Ω / YES / NO / S / B / YES / NO
YES / NO / YES / NO / YES / NO / Ω / YES / NO / S / B / YES / NO
Surge Arrester / Structure Earth / Double Bolted / HF Earth Rod inc Resistance / HF Earth Rod Connected to Earth Grid / HF Down-lead (Straight/Bends) / Corrosion or Damage
YES / NO / YES / NO / YES / NO / Ω / YES / NO / S / B / YES / NO
YES / NO / YES / NO / YES / NO / Ω / YES / NO / S / B / YES / NO
YES / NO / YES / NO / YES / NO / Ω / YES / NO / S / B / YES / NO
YES / NO / YES / NO / YES / NO / Ω / YES / NO / S / B / YES / NO
YES / NO / YES / NO / YES / NO / Ω / YES / NO / S / B / YES / NO
YES / NO / YES / NO / YES / NO / Ω / YES / NO / S / B / YES / NO
Outdoor Switchgear* / No of Structure Earths / Double Bolted / Corrosion or Damage / Separate Handle/Kiosk Earth / Operator Earth Mat Connected to Handle/Kiosk
YES / NO / YES / NO / YES / NO / N/A / NO / YES / N/A
YES / NO / YES / NO / YES / NO / N/A / NO / YES / N/A
YES / NO / YES / NO / YES / NO / N/A / NO / YES / N/A
YES / NO / YES / NO / YES / NO / N/A / NO / YES / N/A
YES / NO / YES / NO / YES / NO / N/A / NO / YES / N/A
YES / NO / YES / NO / YES / NO / N/A / NO / YES / N/A
*Circuit-breakers, disconnectors, fault throwers, earthing switches etc.
Equipment Resistance Measurements
Measure continuity of all equipment, switchgear earth bar and fence connections using a micro-ohmmeter and record below
Equipment / Resistance / Equipment / Resistance
mΩ / mΩ
mΩ / mΩ
mΩ / mΩ
mΩ / mΩ
mΩ / mΩ
mΩ / mΩ
mΩ / mΩ
mΩ / mΩ
mΩ / mΩ
mΩ / mΩ
mΩ / mΩ
mΩ / mΩ
mΩ / mΩ
Stay Wires (note any defects on comments page) / (or n/a)
Mark stay wire positions on the drawing
Check 2m separation between stay wire and fence or other earthed metalwork
Check if insulators fitted
Check if bonded to earthing system
Towers / Tower / Comments
1 / 2 / 3 / 4
Tower Number
Type/Construction
Aerial Earth Wire / YES / NO / YES / NO / YES / NO / YES / NO
Distance from Fence / m / m / m / m
Corrosion or Damage / YES / NO / YES / NO / YES / NO / YES / NO
Visible Earth Connection / Leg 1 / YES / NO / YES / NO / YES / NO / YES / NO
Leg 2 / YES / NO / YES / NO / YES / NO / YES / NO
Leg 3 / YES / NO / YES / NO / YES / NO / YES / NO
Leg 4 / YES / NO / YES / NO / YES / NO / YES / NO
No of Earth Connections
Tower Measurements (special precautions are required for these tests refer to ECS 06-0024)
Current (Rogowski coil) / Leg 1 / A / A / A / A
Leg 2 / A / A / A / A
Leg 3 / A / A / A / A
Leg 4 / A / A / A / A
Tower Voltage (HV probe)[1] / V / V / V / V
Tower Voltage (direct)[2] / V / V / V / V
Tower Resistance / Ω / Ω / Ω / Ω
Tower Leg Designation / 3 / 2 / Substation Fence
4 / 1
Indoor Switchgear
Switchboard / Duplicate Earth Connections ()
Cables (check that all cables are bonded to the switchgear earth bar)
Feeder Number/Name / Cable Sheath Type / Cable Sheath Bonded to Switchgear Earth Bar
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
Fence Earthing (note any defects on comments page) / (or n/a)
Mark all fences on the drawing
Mark all fence earth connections on the drawing
Mark any insulated fence panels on the drawing
Identify any sections of electric fence on the drawing
Check perimeter fence earthing via measurement at multiple points / Independently earthed
Bonded to earthing system
Check whether there are rods at every corner and every 50m (mark on drawing)
Check whether there is an earth 1m either side of each overhead line crossings (mark on drawing)
Check whether potential grading is provided 1m around the outside of the fence (mark on drawing)
Check flexible earth connection between each gate and gate post
Check for bonding (buried) conductor between gateposts
Check if there is any electrode or earthed equipment within 2m of fence
Check 2 metre separation between any internal fence and the perimeter fence
Check condition of fence stand-off insulators and insulated sections (if fitted)
Identify any connections between the substation fence and third party fences (mark on the drawing and note the type of fence and method of connection)
Bonding (note any defects on comments page) / (or n/a
Check all doors bonded to earthing system
Check all staircases bonded to earthing system
Check all ventilation ducts bonded to earthing system
Check all cable supports bonded to earthing system
Check all other metalwork bonded to earthing system
Miscellaneous (record details on comments page) / (or n/a)
Mark positions of lighting columns, security columns and communication masts on the drawing
Check whether they are bonded to the earthing system
Check 2m separation between columns and masts. If an independently earthed fence is installed check for adequate separation between the column/mast and the fence
Check whether line isolation units are installed on telecommunication circuits
Check surface covering for weed growth and deterioration
Check for nearby visible third party buildings and services
Comments/Defects
Test Equipment
Purpose / Make/Type / Serial Number
Certification / ()
All tests have been completed satisfactorily
Earthing system constructed in accordance with latest earthing standards except for any defects/comments detailed above
Contractor Commissioning/Maintenance Engineer (if applicable)
Organisation / Name
Date / Signature
UK Power Networks Commissioning/Maintenance Engineer
Organisation / Name
Date / Signature

© UK Power Networks 2015 All rights reserved1 of 8

[1] If the measured tower voltage is greater than 1V testing shall not proceed.

[2] If the measured tower voltage is greater than 25V testing shall not proceed.