EMC electrical enclosure
Requirements & design
Updated:
What electromagnetic compatibility means, which standards apply and which design measures make an electrical enclosure EMC-compliant — clearly explained by the manufacturer.
Wherever frequency inverters, switched-mode power supplies, servo drives or radio technology are involved, electromagnetic interference occurs. An EMC-compliant electrical enclosure ensures that this interference neither escapes to the outside (emission) nor affects the enclosure’s own electronics (immunity). Without an EMC concept, sporadic malfunctions and data errors are likely — and, if conformity is lacking, legal problems when placing the product on the market.
Short answer: EMC (electromagnetic compatibility) is the ability of a device to function without interference in its environment and not to disturb other devices. An EMC electrical enclosure achieves this with a continuously conductive, closed shielding envelope: conductive connections between all enclosure parts, EMC gaskets, low-resistance equipotential bonding and shielded cable entries. The governing framework is the EMC Directive 2014/30/EU.
What exactly does EMC mean?
EMC has two sides:
- Emission: the device must not disturb its environment beyond permissible limits — neither via conducted interference nor as a radiated field.
- Immunity: the device must be insensitive to external interference (e.g. burst, surge, RF fields, ESD).
The electrical enclosure acts as a Faraday cage: a closed, conductive envelope shields electromagnetic fields. The shielding effect is measured as shielding attenuation in decibels (dB) — the higher, the better.
Relevant standards
- EMC Directive 2014/30/EU — the European basis; a prerequisite for CE marking.
- EN 61439 — low-voltage switchgear and controlgear assemblies; contains EMC requirements for the finished electrical enclosure.
- EN 61000 series — defines emission and immunity (e.g. EN 61000-6-2/-6-4 for industrial environments).
- EN 62208 — requirements for the empty enclosure as the basis.
In practice this means: conformity is declared by the builder of the finished installation — the enclosure manufacturer supplies the EMC-compliant version together with the documentation. Sourcing both from a single supplier avoids interface problems when providing proof.
Design measures for an EMC electrical enclosure
- Continuous shielding: all enclosure parts (body, door, rear panel, side panels, roof) must be electrically conductively connected to one another over a large area. Paint layers at the contact points are removed, or contact washers are used.
- EMC gaskets: conductive gaskets (mesh, elastomer with metal particles) on doors and covers close gaps through which fields would otherwise escape.
- Low-resistance equipotential bonding: a central, short and wide earth connection for all parts — essential for discharging interference currents.
- Shielded cable entries: cable shield braids are clamped over a large area (360°) onto a conductive shield bar, not merely connected via a thin ‘pigtail’.
- Separation of interference and signal lines: route power and control cables physically apart to avoid coupling.
- EMC-compliant screw fastening of the mounting plate and shielding plates.
Shielding attenuation in practice: what do the dB values mean?
Shielding attenuation is stated logarithmically in decibels — small numerical differences mean large differences in effect:
| Shielding attenuation | Field strength is reduced to | Classification |
|---|---|---|
| 20 dB | 1/10 (10 %) | Basic shielding — closed steel body without special measures |
| 40 dB | 1/100 (1 %) | Good shielding — conductively connected surfaces, EMC gaskets on the doors |
| 60 dB | 1/1,000 (0.1 %) | High shielding — complete EMC concept including cable entries, verified by measurement |
As for the sources of interference: in industrial installations, frequency inverters with steep switching edges (interference spectrum extending into the MHz range), switched-mode power supplies and switched inductances dominate. From outside, radio services, mobile communications and ESD discharges act on the equipment. Both directions — emission and immunity — pass through the same weak points of the enclosure.
The key point: the shielding effect is frequency-dependent and is determined by the weakest point. Every unshielded gap, every painted contact surface and every poorly routed cable entry acts like a slot in the Faraday cage — the higher the interference frequency, the smaller the opening that already lets it through. That is why the design (gaskets, contacting, 360° shield termination) determines the result more than the sheet metal itself. The value required depends on the interference environment and the sensitivity of the equipment — proof is provided by measurement on the finished enclosure.
What matters when choosing
An EMC electrical enclosure is always a combination of the enclosure (conductive construction, EMC gaskets) and professional wiring (shield termination, equipotential bonding, cable routing). Both must be right — even the best enclosure is of little use if the cable shields are not terminated correctly. For a tested complete solution, manufacturing from a single source is recommended.
Frequently asked questions — EMC electrical enclosure
When do I need an EMC electrical enclosure?
Whenever strong sources of interference and sensitive equipment come together: frequency inverters and switched-mode power electronics in the enclosure, sensitive sensors and measuring equipment nearby, radio installations on site — or when the system specification explicitly requires compliance with EN 61000-6-2/-6-4. The reverse also applies: anyone who causes interference in neighbouring installations is liable under the EMC Directive 2014/30/EU.
Isn't a standard steel enclosure enough?
A closed steel body provides basic shielding — often that is sufficient. The weak points, however, are door gaps, painted contact surfaces and cable entries: this is where fields escape and enter. The EMC version closes exactly these gaps with conductive gaskets, bare contact points and shielded feedthroughs — only then does the enclosure act as a continuous Faraday cage.
What is the most common mistake in EMC design?
Cable shield termination: if the cable shield is connected only via a thin, twisted ‘pigtail’ instead of being clamped over a large area (360°) onto a shield bar, the shielding effect collapses at exactly that point. In second place: missing or excessively high-resistance equipotential bonding between door, mounting plate and body.
Is an EMC electrical enclosure also dust- and watertight?
EMC gaskets and IP gaskets perform two different functions: one provides electrical conductivity across the gap, the other seals against dust and water. Both can be combined — ZPAS also supplies EMC versions with IP 54/55. More on degrees of protection: IP ratings explained.
The right ZPAS solution
ZPAS offers electrical enclosures in an EMC version with conductive construction and EMC gaskets — the shielding attenuation is verified by measurement. Through its panel building & wiring department, ZPAS supplies on request the fully equipped, EMC-compliant wired and tested enclosure. The EMC variant can also be requested as a door version in the electrical enclosure configurator. Product overview: → ZPAS electrical enclosures & industrial enclosures.
EMC electrical enclosures from the manufacturer — tested and compliant
Describe your application (drives, standards, shielding requirements) — we supply an EMC-compliant enclosure or the completely wired solution. Quotation within 2 working days at most, without obligation.
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