NFPA 780 inspection: the checklist, the intervals and the records
An NFPA 780 inspection checks that an installed lightning protection system is still intact, bonded and grounded as designed. NFPA 780-2026 Section 1.7 requires one every year unless the AHJ sets a different interval. Annex D recommends a visual check at least yearly and a complete, tested inspection every 3 to 5 years.
The yearly check is a requirement in the body of NFPA 780-2026. The detailed intervals, checklists and records come from Annex D, which is informative unless an AHJ, insurer or contract adopts it.
A lightning protection system can sit idle for years, then has to carry a strike in microseconds. Meanwhile roofers move air terminals, clamps work loose, buried electrodes corrode and new rooftop units go in unbonded. Inspection finds those faults before a strike does.
Explosives facilities are the exception. Chapter 8 makes their schedule mandatory: a visual check at least every 7 months (8.9.6) and electrical tests no more than 14 months apart (8.9.7). Buy NFPA 780 from the NFPA for the full text; Lumex is independent of the NFPA.
How often an NFPA 780 system should be inspected
A yearly inspection is the baseline in NFPA 780-2026. Annex D then separates a quick visual check from a complete, tested inspection, and shortens the cycle for critical systems.
| What | How often | Source in NFPA 780-2026 |
|---|---|---|
| Inspection or testing for compliance | Every year, or at an interval the AHJ sets | Section 1.7 (requirement) |
| New system, after installation | Once, on completion | D.1.1 |
| Visual inspection | At least once a year | D.1.1.2 |
| Visual inspection where the climate is severe | Twice a year, or after extreme temperature swings | D.1.1.2 |
| Complete, in-depth inspection | Every 3 to 5 years | D.1.1.2 |
| Critical systems | Every 1 to 3 years, by occupancy or environment | D.1.1.2 |
| After alterations, repairs or a known strike | Each time it happens | D.1.1.1 |
| Explosives facilities: visual inspection | At least every 7 months | 8.9.6 (requirement) |
| Explosives facilities: electrical testing | No more than 14 months apart | 8.9.7 (requirement) |
Annex B points the same way: B.5 recommends a visual check every year and a thorough inspection every five years. D.1.1 lists what should set the interval for a given site: how the structure or area is classified, the level of protection, a corrosive atmosphere, the materials used, the surface the parts are fixed to, and any trouble reports. D.1.1.3 adds a practical point: stagger the visits so that ground resistance is measured in both the hot, dry season and the cool, wet one.
Is Annex D mandatory?
No. Annex D carries the NFPA's standard note that it is informational and not part of the requirements, and it is written as recommendation ("should", "it is recommended"). But inspection is not optional under NFPA 780-2026 as a whole, because several clauses in the body of the standard are mandatory:
- Section 1.6: the owner receives maintenance guidelines when the installation is finished.
- Section 1.7: inspection or testing for compliance happens every year, unless the AHJ chooses another interval.
- Section 1.5.3: where the AHJ asks for it, the finished installation is certified by an on-site inspection from an impartial organization the AHJ accepts.
- Section 4.12.3.4: every concrete-encased electrode has a test or connection point, so the ground system can be tested later.
- Sections 4.19.2.14 and 4.19.2.15: SPDs are installed where they can be reached for inspection, and each one shows visually that it is working.
Section 1.7 changed between editions. The 2020 edition's Section 1.7 left the interval to the AHJ alone; the 2026 text names a yearly default and keeps the AHJ's power to set another. If your inspection programme was written to the 2020 edition and your AHJ never set a schedule, the 2026 edition now gives you one. The NFPA 780-2026 changes guide covers the other differences between the editions.
Annex D can still become binding on a project. An AHJ, an insurer or a maintenance contract can adopt its intervals and checklists by reference, at which point they stop being advice. Read the contract and the local code before you treat the annex as optional.
What a visual inspection and a complete inspection each cover
Annex D splits the work into a walk round with eyes and hands, and a full inspection that adds instrument tests. The second always includes the first.
Visual inspection
Confirms the system is in good repair with no loose joints that could raise resistance, and that corrosion or vibration has not weakened any part. Every down conductor and grounding electrode is whole, every conductor and component is firmly fixed and guarded against knocks, and the building has not grown or changed in a way that needs more protection. SPDs show no sign of damage and, where fitted, their status lights still work. Finally, the system meets the current edition of the standard.
Complete inspection with tests
Everything in the visual inspection, plus three sets of tests. Continuity tests on the parts that were built in during construction and can no longer be seen. Ground resistance tests on the grounding electrode system and on individual electrodes, where they can be disconnected, compared with earlier or original readings. Continuity tests showing that any service or construction added inside the structure since the last visit has been bonded.
The 2026 edition's visual list names SPD status lights explicitly. The 2020 edition asked only for no visible damage to surge devices. That matches the 2026 requirement in Section 4.19.2.15 that every SPD gives a visual indication of its state, so an inspector can now check a light rather than guess.
An NFPA 780 inspection checklist, item by item
A working checklist built from Annex D and the body clauses it relies on. Adapt it to the structure; D.1.4 expects a form that walks the inspector through the site.
| Item | What to check | Source (NFPA 780-2026) |
|---|---|---|
| Strike termination devices | Present where the design shows them, upright, undamaged, not moved by roof work | D.1.2, D.1.5 |
| Roof and down conductors | Unbroken runs, secure fastenings, no mechanical damage or displacement | D.1.2 |
| Connections and splicers | Tight, with no corrosion that could create a high resistance joint; tighten where needed | D.1.2, D.2.2.2 |
| Corrosion protection | Coatings and measures still intact, worst at dissimilar metals and in corrosive air | D.1.1, D.1.5 |
| Grounding electrodes | Intact, and reachable through test points, access wells or hand holes | D.1.2, 4.12.3.4, A.4.12.1 |
| Ground resistance | Measured on the system and on individual electrodes, compared with the baseline; investigate a large change | D.1.3, D.2.2.2 |
| Concealed conductors | Continuity tested where parts were built in and cannot be seen | D.1.3 |
| Bonding of new services | Anything added inside the structure since the last visit is bonded | D.1.3 |
| Building changes | No extension, rooftop plant or new projection left outside the protection | D.1.1.1, D.1.2, D.2.2.2 |
| SPDs | Accessible, undamaged, status indication working; compare performance with a new device | 4.19.2.14, 4.19.2.15, D.1.2, D.2.2.2 |
| Compliance | Any gap against the current edition noted and reported | D.1.2, D.1.5 |
| Records | Readings, conditions, departures and repairs written up against the as-built drawings | D.1.5, D.2.3, A.1.6 |
Ground resistance is measured with the three-point method in Annex E, which is also informative. E.1.3 places the potential probe at 62 percent of the distance to the current probe, and E.1.4 warns that soil moisture and temperature move the reading. D.1.1.3 advises testing in different seasons for the same reason. Annex D sets no fixed resistance figure for these tests. D.1.3 compares each reading with earlier or original readings, or with values accepted for that soil, and asks for a large difference to be investigated. For what NFPA 780 asks of the grounding itself, see the NFPA 780 grounding and bonding guide.
What records to keep after an inspection
A reading on its own tells you little. A ground resistance of any value only means something when it sits next to the reading from the same electrode, taken the same way, in a similar season, last year and at handover. That is why NFPA 780-2026 puts so much weight on records.
D.1.5 asks the inspector, or the body responsible for inspection, to build and keep records of five things: the overall state of the air terminals, conductors and other parts; the condition of corrosion protection; how securely conductors and components are attached; resistance readings from the parts of the grounding electrode system; and any departure from the standard. D.2.3 adds a full record of maintenance work and of corrective actions taken or planned, so the programme itself can be reviewed and improved.
Two documents make those records usable. The first is the inspection form: D.1.4 expects one to be prepared for whoever inspects the system, detailed enough to cover installation methods, the type and condition of components, test methods and how readings are recorded. The second is the as-built drawing set. A.1.6 says that when a system is upgraded, the drawings should be revised and should show test point locations, and that where the AHJ requires it, test records of the new configuration should become the baseline for future measurements.
When to re-inspect outside the normal schedule
The calendar is only one trigger. NFPA 780-2026 D.1.1.1 recommends an extra inspection in two situations: whenever the protected structure is altered or repaired, and after any known lightning discharge to the system. The first matters most. Annex B (B.5) traces damage on protected structures to later additions or repairs, or to wear nobody caught, and the lightning protection contractor is seldom told when building work starts.
- Reroofing or roof repairs. Conductors are lifted and not refixed, air terminals are left lying on the membrane.
- New rooftop plant, masts, antennas or solar. New metal bodies that may sit outside the zone of protection or need bonding.
- Extensions and new wings. The visual checklist in D.1.2 asks directly whether additions now need more protection.
- New services entering the building. D.1.3 asks for continuity tests to confirm they have been bonded.
- A strike, or a suspected one. Look for burnt or melted parts, damaged SPDs and a changed ground reading.
A.1.6 goes further for structures that have been added to or altered: it recommends bringing them into line with the current edition, revising the as-built drawings and, where the AHJ asks, taking new test records as the fresh baseline.
Explosives facilities: a stricter, mandatory schedule
For structures housing explosives, NFPA 780-2026 moves inspection out of the annex and into the requirements, on a much shorter cycle.
A written plan and AHJ sign off
Every protection system on an explosives structure needs a maintenance and inspection plan (8.8). The AHJ inspects the first installation, and the system is inspected again and recertified after any work on the structure (8.9). Discrepancies are repaired before explosives work resumes (8.9.2).
Visual checks every 7 months
A visual inspection for corrosion and broken wires or connections at least every 7 months, with repairs made at once and damage entered in the test records. SPDs installed under Section 4.19 are checked on the same cycle and after any suspected strike (8.9.6.3).
Electrical tests every 14 months
Electrical testing at least every 14 months. No single bonded object may exceed 200 milliohms of dc resistance (8.9.7.1). Earth resistance uses the three-point fall of potential method; a clamp-on meter is allowed only where the site makes the test stakes impossible and the AHJ permits it (8.9.7.6). Instruments must be made for earth resistance testing and kept calibrated (8.9.7.4, 8.9.7.5).
Chapter 8 also bars inspection and testing while a thunderstorm threatens (8.9.5), asks for any strike damage to be documented and reported at once (8.9.3), and requires the resistance and bonding records to be kept for a period the AHJ accepts (8.9.7.7). In the 2020 edition the same inspection clauses sat one number higher, under 8.10. The NFPA 780 tanks and explosives guide covers what Chapter 8 requires of the protection itself.
Who can inspect and certify an NFPA 780 system
NFPA 780-2026 does not license inspectors, and the NFPA does not inspect or certify installations itself (A.3.2.1). Acceptance runs through the AHJ, which the standard defines broadly: a building official, a fire marshal, an electrical inspector, an insurer's inspection department, or in many cases the owner or the owner's agent (A.3.2.2).
The standard gives the AHJ three levers. Section 1.5.2 has the AHJ certify the people responsible for the installation as fit for the work. Section 1.5.3 lets the AHJ require the completed installation to be certified by a physical site inspection, carried out by a qualified organization that is impartial and that the AHJ accepts. And Section 1.7 lets the AHJ set its own inspection interval in place of the yearly default. For periodic inspections, Annex D speaks of whichever person or body is responsible for inspecting the system (D.1.4, D.1.5), without naming a qualification.
Explosives facilities are the exception again. Section 8.9.7.3 requires testing by people familiar with lightning protection testing, and 8.9.7.8 allows only trained, expert personnel to maintain, inspect and test these facilities. In practice, when a project talks about recertification, it means the AHJ's route under 1.5.3 or Chapter 8. Ask the AHJ and the insurer which organizations they accept before you book the visit.
Common mistakes an NFPA 780 inspection finds
The faults below are the ones later building work and years of unchecked wear leave behind.
Roof work that nobody told the installer about
Conductors cut to lay a new membrane and never reconnected. Air terminals removed for access and left loose. New plant, railings or panels placed outside the protected zone. D.1.1.1 exists for exactly this.
No baseline to compare against
D.1.3 judges a ground reading mainly against earlier ones. Without handover readings, test point locations on the drawings (A.1.6) and the same method each time, a large change in resistance goes unnoticed.
Electrodes that cannot be reached
Paving or planting laid over the ground connections, with no access well or test point. The electrode may be fine, but nobody can prove it. See 4.12.3.4 and A.4.12.1.
SPDs out of sight and out of service
A surge device buried behind other equipment, with its status window dark or never checked. Sections 4.19.2.14 and 4.19.2.15 require access and a visible indication; the NFPA 780 surge protection guide covers where they go.
New services left unbonded
A new gas line, data cable or water service added years after handover and never bonded. The visual walk will not find it; the continuity test in D.1.3 will.
Treating the current edition as a pass or fail line
D.1.2 compares the system with the current edition, but Section 1.4.1 does not make a new edition retroactive unless a clause says so or the AHJ applies it under 1.4.2. Report the gaps; the owner and AHJ decide on upgrades.
Turning inspection into a maintenance programme
Inspection finds the faults; maintenance fixes them. D.2.1 explains why even a well designed system needs both: corrosion, weather and strikes wear parts down over the years.
D.2.2.1 recommends a periodic maintenance programme for every system, paced by weather damage, how often and how badly the structure is struck, and the level of protection it needs. D.2.2.2 asks for that programme to sit inside the building's general maintenance plan, built around a routine list that is repeated the same way each time. Its suggested content lines up with the checklist above: inspect conductors and components, tighten clamps and splicers, measure system and electrode resistance, check surge protection against a new device, refix loose parts, and test whether changes to the building have reduced the protection.
The risk assessment behind the system, kept current
Lumex runs the NFPA 780-2026 Annex L risk assessment, the quick screen and the detailed R1 to R4 assessment, shows the working behind every figure and produces a signed-off report. For NFPA 780, the first report sets a suggested review-due date 12 months later, which the engineer can change, and Lumex sends a reminder as it comes up. The 12 months matches the yearly cycle of Section 1.7 and D.1.1.2. It is Lumex's suggestion for reviewing the assessment, not an inspection of the system.
Lumex does not inspect or test a system, design the protection or certify a structure, and periodic inspection reports are coming soon. Where an inspection finds the structure has changed, Lumex gives you a dated, signed Annex L assessment to rerun, with the working behind every figure. Start an NFPA 780 risk assessment.
Related reading: which lightning standard applies to your project, NFPA 780 explained chapter by chapter, the Annex L risk assessment, grounding and bonding under NFPA 780, surge protection under NFPA 780 and how inspection works under IEC 62305-3.
Questions answered
How often should a lightning protection system be inspected under NFPA 780?
What does an NFPA 780 inspection include?
Is Annex D of NFPA 780 mandatory?
Who can inspect a lightning protection system under NFPA 780?
When should a system be re-inspected outside the normal schedule?
How often are explosives facilities inspected under NFPA 780?
What records should be kept after an NFPA 780 inspection?
What ground resistance should an NFPA 780 inspection read?
Does an existing system have to be upgraded to the 2026 edition after an inspection?
Lumex computes the method of the standard you choose, IEC 62305-2:2024, AS 1768:2021 or NFPA 780-2026, and shows the working. It does not certify a structure. You may not issue or submit a Lumex output until a competent person, qualified where the structure is located, has reviewed the inputs and the result and signed it.
NFPA 780-2026 Annex L gives default tolerable values of 1E-5 per year for loss of life or injury and 1E-3 for loss of service and of historical significance, and the owner or the authority having jurisdiction may set others. Every NFPA 780 assessment in Lumex states the values that applied.
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