NEN 3840: the safety standard for high voltage
NEN 3840 is the Dutch standard for working safely on high-voltage installations (above 1000 V AC / 1500 V DC), such as transformer substations, high-voltage pylons and 10 kV panels. Here you can read what the standard involves.
When does NEN 3840 apply?
As soon as you work on installations above the low-voltage limit (1000 V AC), NEN 3840 applies. In practice that means medium-voltage substations (10 kV, 20 kV, 50 kV), high-voltage networks (110 kV and above) and transformer panels.
What is different from NEN 3140?
With high voltage the risks are orders of magnitude greater: arc flash, induction, clearance requirements. Procedures are stricter and the authorisation requirements are tougher.
- AAB measurement (afwezigheid bedrijfsspanning: absence of operating voltage) instead of SLA
- Larger safety distances (e.g. 1.5 m at 50 kV)
- Arc flash helmet and fully insulated PPE mandatory
- Selection device (SEL) after earthing, before every action
Authorisation levels for HV
For NEN 3840 the levels are VP*** and VP**** (carrying out work) and IVWV*** and IVWV**** (responsible). For pure high-voltage work, at least *** is required. The official exam is in Dutch, so it helps to know the Dutch terms.