Close Inspection Grade — IEC 60079-17
The close inspection grade is the most commonly performed periodic inspection for Zone 1 Ex equipment. It includes everything in a visual inspection plus checks that require the equipment to be opened, accessed, or disturbed — without necessarily using measurement instruments.
What Close Inspection Adds to Visual
Close inspection requires the equipment to be de-energised and isolated. It then includes:
- Opening the enclosure — checking internal condition, cleanliness, moisture, corrosion
- Cable gland thread engagement — verifying minimum 5 full turns for Ex d entries
- Flamepath surface condition — visually examining without measuring (measurement is Detailed grade)
- Terminal condition — checking conductor exposure, ferrule presence, correct identification
- Stopping plug engagement — verifying minimum thread turns
- IP gasket condition — checking for compression set, cracking, correct seating
- Internal wiring — cable condition, routing, correct identification
Close Inspection in Practice
A periodic close inspection of an Ex d motor junction box would typically include: isolating the equipment, opening the cover, checking gland thread engagement on all entries, verifying all conductors are correctly ferrulled and identified, checking the internal earth link, examining the cover gasket, and closing and re-bolting correctly. All bolts must be returned and torqued to the correct specification.
One of the most common close inspection findings is insufficient cable gland thread engagement — particularly where glands have been disturbed during previous maintenance and not correctly re-engaged. Less than 5 full turns of thread engagement in an Ex d threaded entry is a Category X deficiency, requiring immediate action.
Documentation
Results of close inspection must be recorded in the inspection schedule, including: date, inspector, equipment tag, deficiencies found, their classification, and action taken or planned. IEC 60079-17 requires this documentation to be maintained and available for review.
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