§704 — Temporary installations on construction and demolition sites

Construction and demolition sites have their own norm chapter, §704, because the conditions structurally differ from a fixed installation: temporary cabling, weather exposure, heavy and portable tools, and users who are not always electrotechnically trained. §704 therefore imposes stricter requirements than a comparable circuit in a fixed installation.

RCD obligation

All circuits supplying socket outlets or hand-held tools up to and including 32 A must be protected by:

• an RCD with I∆n ≤ 30 mA, or
• SELV/PELV, or
• electrical separation (one consumer per isolating transformer).

This is the same 30 mA threshold as for personal protection elsewhere in NEN 1010 (§411.3.3, §701, §708) — however, on a construction site there is no exception for circuits that would normally fall under a higher threshold: all socket-outlet and hand-tool circuits up to 32 A must comply with this, without the usual room-dependent nuances of a fixed installation.

Construction distribution boards (distribution equipment on site)

• Construction distribution boards must comply with NEN-EN-IEC 61439-4, the standard for distribution equipment specifically intended for construction sites (ASC — assemblies for construction sites).
• A suitable degree of protection against weather and mechanical damage is required — in practice this generally means at least IP44 for outdoor placement, higher under heavier exposure (e.g. splash water from construction traffic).
• Boards must be periodically inspected by a competent person — the construction site environment (vibration, moisture, dust, collisions) accelerates wear compared with a fixed indoor installation.

Why this is relevant for VP/VOPs

Construction site installations are often managed by the contractor who rents or places the site power supply, not by the eventual building manager. A VP inspecting or assessing a construction site installation must know the §704 requirements as a separate scope of application — just as with other special locations (bathrooms §701, swimming pools, agricultural premises §705), requirements apply here that do not automatically follow from the general rules of chapter 4.

Common mistakes

1. Using ordinary (non-construction-site) distribution boards on a construction site — these often do not meet the required degree of protection against weather and mechanical damage.
2. Assuming 30 mA only applies to "damp locations" — on a construction site the 30 mA requirement applies to virtually all socket-outlet/hand-tool circuits up to 32 A, regardless of whether the location is "wet".
3. Skipping periodic inspection because the installation is "temporary" — it is precisely the temporary, heavily loaded and weather-exposed nature of a construction site installation that makes periodic inspection extra important, not redundant.
4. Confusing §704 with an ordinary outdoor installation — a garden connection or outdoor lighting at a fixed dwelling does not fall under §704; that chapter is specific to installations during the construction/demolition period itself, intended to be removed again once the work is complete.

Related

• §531 — Residual Current Devices (RCD)
• §701 — Bathrooms and shower rooms
• §414 — SELV, PELV & FELV