§444 — Measures against electromagnetic disturbances (EMC) in building installations

The guide on EMC separation of power and data cabling covers one specific, common measure: sufficient distance between power-carrying and data/signal cabling to limit inductive and capacitive coupling. This article covers the broader chapter that measure comes from: §444 of NEN 1010 (IEC 60364-4-44), titled "Measures against electromagnetic interference (EMI) in installations of buildings".

Why §444 is different from §442/§443

The chapters around §44 each address a different kind of disturbance:

• §442 covers the temporary overvoltage that arises from a fault between a high-voltage system and the low-voltage network (see the related guide).
• §443 covers atmospheric and switching overvoltages (lightning strikes, switching operations) and the corresponding surge protection (SPD; see the SPD guide).
• §444 covers a fundamentally different phenomenon: electromagnetic interference (EMI) in the broad sense — conducted and radiated disturbances, harmonics, transients, and radio-frequency coupling — and the immunity of the installation and the equipment connected to it (especially IT and electronic equipment) against those disturbances, alongside limiting the emission FROM the installation itself.

An SPD (§443) protects against an excessive voltage spike; §444 addresses the broader electromagnetic environment of the installation, regardless of whether the disturbance manifests as a voltage spike, a high-frequency noise current, or a magnetic field.

Core measures from §444

• A well-meshed bonding network instead of a star-shaped earthing arrangement: in buildings with a lot of sensitive IT and electronic equipment, a fine-meshed bonding network (multiple, interconnected bonding points instead of a single star point) reduces high-frequency voltage differences between pieces of equipment — a star-shaped network has a considerably higher impedance at high frequency between widely separated points.
• Separation of power and signal circuits: exactly the subject of the EMC separation guide — sufficient distance between power and data cabling, or screening where distance isn't feasible.
• Limiting loop area: routing the protective conductor as close and parallel as possible to its associated line and neutral conductors, instead of a separate, widely diverging route — a larger loop area between the outgoing and return conductor picks up more energy from an external magnetic field and induces a higher disturbance voltage.
• Managing harmonics: distorted, non-sinusoidal currents (from rectifiers, variable-frequency drives, LED drivers) are themselves a source of conducted EMI within the installation — see the harmonics/THD guide for the background of that phenomenon.
• A point of attention per earthing system: a TN-C installation (where the neutral and protective conductor are combined in the PEN conductor) inevitably allows part of the operating current to flow via all parallel PE paths — including cable trays, armouring, and building steel — causing magnetic fields and noise that a TN-S installation (separate N and PE) does not have. For buildings with disturbance-sensitive equipment, TN-S is therefore preferable to TN-C from an EMC standpoint.

Note: §444 formulates these measures as general recommendations that must be weighed per situation (type of equipment, size of the building, presence of power electronics) — it is not a table of fixed, universally applicable limit values like, for example, the disconnection times of §411.

Practical relevance

When designing an installation for a building with a lot of sensitive IT, measurement, or control equipment (data centres, hospitals, industrial control rooms), it is not enough to only check the cable separation distances of §444.4 — the quality of the bonding network, the earthing system (TN-S versus TN-C), and the presence of harmonic sources must be assessed together, because each of these factors can independently already cause interference complaints, even when the cable separation itself is executed perfectly.

Common mistakes

1. Confusing §444 with surge protection (§442/§443) — SPDs protect against voltage spikes; §444 addresses the broader electromagnetic environment and immunity of the installation.
2. Applying TN-C within a building with a lot of sensitive equipment to save on wiring cost, without weighing the EMC drawbacks (current on parallel PE paths, magnetic fields).
3. Focusing exclusively on cable separation distances and neglecting the quality of the bonding network or the loop area of the wiring — both are equally relevant measures from the same chapter.
4. Only treating harmonic sources (VFDs, LED lighting) as an EMC issue after interference complaints are reported, instead of accounting for them at the design stage.

Related

• EMC — separation of power and data cabling
• §442 — Temporary overvoltage due to a high-voltage earth fault
• Surge protection (SPD)
• Harmonics & THD