Field Notes
Grounding electrode test records before permanent power release
A useful grounding electrode test packet ties the electrode system, bonding state, test method, meter, probe geometry, soil conditions, readings, criterion, exceptions, photos, and release decision together before permanent power is released.
Direct answer
Before permanent power release, record the grounding electrode system boundary, electrode types and locations, grounding electrode conductor, bonding jumpers, connection hardware, test wells, drawings and specification basis, test method, meter make, model, serial number and calibration status, weather and soil conditions, whether the electrode was isolated or bonded during the test, probe direction and spacing, readings at each probe position, curve or plateau review, project acceptance criterion, open exceptions, photos, reviewer, and release decision.
The record should separate three different questions: what was installed, how it was tested, and who is allowed to release permanent power. A low resistance reading does not prove every bond is correct. A continuity check does not prove earth resistance. A field note does not replace the AHJ, engineer, owner, utility, commissioning plan, or qualified electrician.
Use this field note as documentation guidance only. The adopted code, AHJ, engineer of record, utility rules, project specifications, test standard, grounding tester manual, qualified electrical contractor, commissioning authority, and site safety plan control the actual installation, testing, correction, release, and energization.
Permanent power release needs more than one number
Grounding electrode testing often gets reduced to one value in ohms. That value matters only when the packet shows what electrode system was tested, how it was connected during the test, what method was used, where the auxiliary probes were placed, and what acceptance criterion applied to that project.
The release risk is usually hidden in the missing details. If the utility neutral was already connected, building steel was still bonded, the water service bond was open, the test well was mislabeled, the probe line crossed buried metal, or the meter was out of calibration, a clean-looking number can mislead the next reviewer.
Treat the grounding electrode test record as a gate packet before permanent power review. It preserves the field evidence, but it does not authorize energization by itself.
Define the electrode system before testing
Start by naming the exact electrode system under review. Record whether the installation includes driven rods, a ground ring, concrete-encased electrode, building steel, metal underground water piping, a ground grid, counterpoise, transformer-yard electrodes, test wells, communications bonding bars, lightning protection conductors, or other project-defined electrodes.
Then record the connections that make the system real. Capture grounding electrode conductor size and route, irreversible or mechanical connectors, exothermic weld locations, bonding bushings, main bonding jumper status where applicable, water pipe jumper status, building steel bond, ground bar labels, corrosion protection, physical protection, and any connection left open for testing.
Use the same names the drawings, specifications, equipment labels, test wells, and commissioning forms use. If the test report says TW-2 but the drawings call that point GR-1, the packet should reconcile the labels before permanent power review.
Choose a method and record its limits
For installed electrode resistance, the common field method is a fall-of-potential test using auxiliary current and potential probes. The packet should say whether the test was three-point, four-point, selective, clamp-on, stakeless, or another project-approved method, and why that method was suitable for the site condition.
For fall-of-potential testing, preserve the geometry. Record current probe distance, potential probe positions, probe-line direction, probe depth, lead routing, test-well or electrode connection point, whether the electrode was isolated, nearby buried metal or parallel paths, and any obstruction that forced a shortened or angled layout.
Clamp-on and stakeless methods can be useful when their assumptions fit the system, but they are not a blank substitute for a full electrode resistance test. If the method depends on parallel grounding paths, a closed loop, or an energized service state, write that clearly and identify who accepted the method for the release packet.
Soil, weather, and site geometry belong in the report
Ground resistance readings are affected by soil conditions and test geometry. Record soil type where known, surface condition, recent rain, dry period, frozen soil, standing water, paved areas, rock, irrigation, construction water, and whether probe contact had to be improved.
The probe line should be reviewable later. Record the direction from the electrode, distance to the current probe, each potential probe station, whether the line crossed duct banks, rebar mats, fences, metal piping, rails, building steel, temporary power conductors, communications pathways, or other conductive objects.
If the site does not allow a clean probe layout, do not hide that fact. Write the obstruction, alternate direction, shortened distance, repeated run, no-plateau result, or engineering review needed before release.
Record the readings, not only the conclusion
The report should include raw readings at each probe position and the final interpreted value. For a fall-of-potential test, include at least the project-required positions and enough points to show whether the curve flattened. Many crews record readings around 52, 62, and 72 percent of the current-probe distance where that method is appropriate, but the project procedure controls the required points.
Do not turn a common rod-electrode resistance value into a universal acceptance rule. If the project or AHJ uses a resistance threshold, record the exact source, such as the specification, drawing note, owner standard, test plan, or engineer direction. If the criterion is not known, the release decision is not ready.
Also record retests and corrections. Added rods, repaired connections, reworked bonds, moisture changes, probe relocation, longer spreads, meter changes, or repeated readings should stay in the packet so the final value does not erase the path that produced it.
Minimum grounding electrode test packet
Use the project specification, commissioning form, test agency report, electrical contractor QA form, or owner release checklist first. Add this packet where those records do not connect the physical electrode system, test setup, readings, and release decision clearly enough.
| Record item | Field detail | Why it matters |
|---|---|---|
| System boundary | Service, switchgear, transformer, yard, building, room, gridline, test well, drawing revision | Shows exactly what permanent-power release area the test supports |
| Electrodes | Rods, ring, grid, concrete-encased electrode, building steel, water pipe, counterpoise, test wells | Prevents a resistance number from being detached from the installed system |
| Bonds and conductors | Grounding electrode conductor, bonding jumpers, connection type, labels, physical protection, open links | Separates electrode resistance from bonding completeness |
| Test basis | Specification, drawing note, owner standard, test plan, AHJ or engineer criterion | Makes the pass or hold decision traceable |
| Meter | Manufacturer, model, serial number, calibration date or status, leads, clamps, accessory probes | Keeps the measurement chain reviewable |
| Method | Fall-of-potential, selective, clamp-on, stakeless, continuity, soil resistivity, or other approved method | Avoids mixing different tests into one conclusion |
| Setup | Isolated or bonded state, probe direction, distances, probe depth, lead routing, nearby conductive paths | Shows whether the geometry supports the reading |
| Conditions | Weather, recent rain, dry period, frozen or saturated soil, pavement, rock, irrigation, construction water | Explains why readings may differ from a later test |
| Readings | Raw values, repeated values, 52/62/72 checks where used, curve or plateau review, interpreted value | Lets a reviewer see more than the final number |
| Release | Pass, hold, partial release, release with named exception, reviewer, date, next action | Keeps test completion separate from energization authority |
Before permanent power release checklist
Run this check before the test report is used to support permanent service release, switchgear energization, utility coordination, or commissioning turnover.
- Confirm the release boundary: service, gear lineup, transformer, yard, room, floor, gridline, or test well.
- List the grounding electrode system components and tie them to drawings, specifications, labels, and photos.
- Record grounding electrode conductor, bonding jumpers, connection hardware, corrosion protection, and physical protection status.
- Record whether any bond, link, neutral, utility connection, water pipe bond, communications bond, or lightning protection bond was open, temporary, or disconnected for testing.
- Identify the accepted test method and the document or reviewer that allowed it.
- Record meter manufacturer, model, serial number, calibration status, lead set, clamps, probes, and technician.
- Record probe direction, current probe distance, potential probe positions, probe depth, lead routing, and nearby conductive paths.
- Record soil, pavement, moisture, recent weather, frozen ground, rock, standing water, irrigation, or construction-water conditions.
- Attach raw readings, repeated readings, curve or plateau review, final interpreted value, and any no-plateau explanation.
- Record the project acceptance criterion and its source instead of relying on an assumed universal ohm value.
- Attach photos of test wells, electrode access points, conductor connections, labels, meter screen, probe line, and obstructions.
- Write the final status: released to permanent-power review, partial release, release with named exception, retest required, correction required, or hold.
Weak and strong test notes
Weak note: ground test passed, ready for permanent power.
That note does not identify the electrode system, bonding state, method, meter, probe geometry, soil condition, readings, criterion, photos, reviewer, or actual release authority.
Stronger note: Grounding electrode test for service gear MSB-1 completed before permanent-power review on 2026-06-09. Electrode system included building steel bond, concrete-encased electrode along grid A/1 to A/5, ground ring around the electrical yard, and two supplemental rods at transformer T-1. Drawing E5.01 revision 7 and specification 26 05 26 used as the test basis. Grounding electrode conductor and bonding jumpers photographed at MSB-1, water service, building steel, ground ring test well TW-2, and transformer yard. Fall-of-potential test performed at TW-2 with the electrode isolated per the test plan. Meter make, model, serial number, and calibration date recorded. Current probe set 300 ft east; potential probe readings recorded at 52, 62, and 72 percent. Readings were 3.9, 4.1, and 4.0 ohms with no large spread. Soil dry, no rain for 72 hours, utility neutral not connected. Clamp-on checks at supplemental rods recorded as supplementary only. Project criterion came from specification 26 05 26 and the approved test plan. Released to AHJ, utility, and commissioning review; energization remains under the approved electrical procedure.
The stronger note works because it tells a reviewer what was tested, how it was tested, which assumptions were controlled, and which authority still owns energization.
Common mistakes
The first mistake is writing only the final resistance value. A number without method, geometry, bonding state, and criterion is not a release-ready record.
The second mistake is treating continuity and ground resistance as the same test. Bonding continuity can show an electrical path between conductive parts. Ground resistance testing evaluates the electrode system's connection to earth under the selected method. Both can matter, but one does not automatically replace the other.
The third mistake is ignoring parallel paths. Building steel, water piping, utility neutral, cable shields, communications grounding, lightning protection, fences, and rebar can change what the meter sees. Record whether those paths were intentionally included or isolated.
The fourth mistake is assuming a 62 percent reading is valid on every site. The simplified point is useful only when the electrode and probe geometry meet the method assumptions. If readings do not form a stable curve, keep testing or send the packet for review instead of forcing a pass.
The fifth mistake is using a common 25 ohm rod value as a universal release threshold. Project specifications, adopted code, AHJ decisions, owner standards, engineered designs, and equipment requirements may set different acceptance requirements or no simple resistance threshold at all.
The sixth mistake is letting permanent power proceed while a physical connection is still undocumented. Missing exothermic weld photos, open bonding jumpers, unidentified test wells, damaged grounding conductors, or unknown calibration status should be treated as release issues, not paperwork cleanup.
Questions that come up
Can a clamp-on tester replace a fall-of-potential test? Sometimes it can support a project-approved method, and sometimes it cannot. The record should state why the selected method fits the grounding system, what parallel paths exist, and who accepted that method for the release packet.
Should the electrode be isolated for testing? Use the project test plan, tester manual, engineer direction, and safety procedure. Isolation can make the electrode under test clearer, but disconnecting grounding or bonding paths can create hazards and must be controlled by qualified personnel.
Does a low resistance value prove the system is bonded correctly? No. A resistance value can support one part of the grounding review. It does not prove every bonding jumper, equipment grounding conductor, connector, label, torque, corrosion protection, or neutral bond is correct.
What if the site cannot support the required probe distance? Record the obstruction and alternate setup. A shortened spread, angled line, or no-plateau result may require a different method, longer layout, multiple runs, engineering review, or a release hold.
Is soil resistivity the same as installed electrode resistance? No. Soil resistivity helps design and evaluate site conditions. Installed electrode resistance testing evaluates the constructed electrode system using the selected test method.
Compliance and safety limits
This field note is not an electrical design, code interpretation, grounding calculation, soil model, test standard, utility approval, energized-work permit, lockout procedure, excavation permit, commissioning approval, or manufacturer instruction. The adopted code, AHJ, engineer, utility, project specifications, test plan, meter manual, qualified electrician, commissioning authority, and site safety plan control the work.
Do not use this checklist to bypass lockout, energized-work controls, PPE, utility coordination, excavation and locating requirements for auxiliary probes, storm and lightning hazards, live grounding-system disconnection controls, temporary-power safety, generator or transformer safety, switchgear procedures, traffic control, fall protection, confined-space rules, or required inspections. The packet preserves the grounding test and release record. It does not authorize unsafe work or unapproved energization.
Sources checked
- NFPA, The Basics of Grounding and BondingUsed for grounding and bonding distinctions, including the difference between connection to earth and electrical continuity between conductive parts.
- OSHA, 29 CFR 1926.404 Wiring Design and ProtectionUsed for construction electrical safety boundaries around grounding, continuity, wiring protection, and ground-fault protection context.
- NASA UFGS 26 05 26.00 40, Grounding and Bonding for Electrical SystemsUsed as a facility grounding and bonding specification example for electrode systems, bonding, submittals, inspection, and test-report context.
- IEEE Std 81-2025, Measuring Earth Resistivity, Ground Impedance, and Earth Surface PotentialsUsed for the standards basis around earth-resistivity and ground-impedance measurement terminology and method selection.
- AEMC, Understanding Ground Resistance TestingUsed for fall-of-potential testing, auxiliary probe layout, 62 percent checks, soil condition context, selective and clamp-on methods, and recordable field readings.
- Fluke, Do Not Forget the Grounding SystemUsed for grounding-system testing context, periodic verification themes, and the importance of documenting grounding performance.
- UL Solutions, Grounding and Lightning Protection Component EvaluationsUsed for product evaluation context around grounding and lightning-protection components, connectors, and listing evidence.
- DOD UFGS 27 05 26, Grounding and Bonding for Communications SystemsUsed for communications grounding and bonding coordination context where electrical and communications grounding records meet.