Thermographic inspection & NTA 8220 — fire risk class
Thermographic inspection & NTA 8220 — fire risk class
Thermographic inspection (infrared inspection) detects heat development in connections, contacts and components that is not yet visible or noticeable — a loose terminal connection or an overloaded contact often becomes warm well before smoke, odour or visible damage occurs. This makes thermography a valuable supplement to a regular NEN 3140 inspection, but not a replacement for it.
Two different objectives: NEN 3140 versus NTA 8220
- NEN 3140 assesses the safety of persons — whether the installation or the piece of equipment is safe to touch and operate.
- NTA 8220 ("Method for assessing electrical equipment for fire risk") specifically assesses the fire risk of electrical equipment — a different assessment objective that is often combined with a NEN 3140 inspection moment, but produces a separate report alongside it.
Thermography according to NPR 8040-1 is the standardised execution method for the IR inspection that underlies an NTA 8220 assessment.
The three risk classes of NTA 8220
| Class | Meaning | Follow-up action |
|---|---|---|
| Class 1 (low risk) | No defects that constitute a direct fire risk. | Re-inspection within the usual interval (guideline 3–5 years). |
| Class 2 (limited risk) | Points of attention/defects that could pose a risk over time. | Remediate within a reasonable period (NTA 8220 applies a guideline period of a maximum of 3 months for this). |
| Class 3 (high risk) | Direct fire hazard. | Immediate action required — do not wait until the next scheduled inspection. |
Class 3 is not a "schedule this for next month" finding: the nature of the finding (direct fire hazard) requires immediate intervention, comparable to how an IV-3 finding during a regular NEN 3140 inspection requires immediate action.
What thermography does and does not detect
- Detects well: heat development caused by increased contact resistance (loose terminals, corrosion at contact points, overloaded connections, uneven load distribution across phases).
- Does not detect: insulation faults without heat development, earthing problems, or continuity faults that carry no current at the moment of the recording — a thermographic inspection must be carried out with the installation under representative load, otherwise warm spots remain invisible.
Common mistakes
- Viewing thermography as a replacement for NEN 3140 instead of a supplement — the two assess different risks (personal safety versus fire risk) using different assessment frameworks.
- Measuring at low load — an installation that is barely loaded during the recording shows no heat development, even though a real problem exists that only becomes visible under full load.
- Leaving Class 2 findings until the next regular inspection — NTA 8220 expects remediation within the set period, not only at the next annual or periodic round.
- Not following the NPR 8040-1 methodology — an ad-hoc IR recording without a standardised execution (distance, angle, emissivity setting, load conditions) does not produce a usable NTA 8220 classification.
Related
Further reading
- InspectieInspection report, risk class & liability — what a NEN 3140 inspection legally means for companies
- §3.6Danger zone and approach zone — the three types of electrical work
- PBMPPE for electrical work — overview and classifications
- §6.3Arc flash — risk, energy and PPE
- §6.3Live working (WOS) — when is it allowed and with what protection?
- InspectieATEX & explosion-hazard zones — classification, inspection and relevance for horticulture