How often
For this equipment family the inspection interval is one year unless the relevant standards set a different period. Where a standard sets a shorter interval, the shorter one applies; where the manufacturer's instruction requires more frequent checks, that is followed. The validity of an inspection depends less on its interval than on what the report contains.
Looking at it as a chain
The air termination, the down conductor and the earth electrode work together. An inspection that only looks at the rod on the roof misses that the down conductor may have parted somewhere — and that break produces the same outcome as having no installation at all.
Common defects
Corroded connections, a conductor cut by later roof work, metal equipment such as air conditioners and aerials added afterwards and left outside the protected volume, and a test clamp that cannot be reached.
If the building changes
When equipment is added to the roof or the building is raised, the protected volume changes. It is reassessed without waiting for the interval.
In Optifora
The periodic inspection module records the equipment, sets its interval by family, reminds you as the date approaches, and attaches the report to the equipment's record. Equipment past its date appears separately in the list and counts as high risk in the assessment.