Telecom, rail and urban infrastructure: EMI shielding and thermal materials

Public networks no longer stay in the equipment room. 5G relies on many small cells instead of a few tall masts, and those radios now sit outdoors, on street furniture. Tram and metro systems run on signalling, telecommunications and ticketing equipment; gateways, access-control readers and sensors equip connected buildings. None of these units may disturb its neighbours, and each has to keep working beside them: that is electromagnetic compatibility (EMC).

For the housing, two questions come first: where is the unit installed, and how often is it opened? ElectroDome supplies the EMI gaskets that keep a housing electrically closed at its joints, and the thermal pads that lead the heat of its electronics to the wall. This page follows the equipment from the mast to the meeting room.

📡 Equipment concerned

• Telecom and networks: small cells and radio units, base stations, 19-inch racks, street cabinets.
• Public transport: signalling, telecommunications and ticketing equipment for metro, tram and bus.
• Urban equipment: information terminals, CCTV cameras, environmental sensors.
• Connected buildings: controllers, gateways, IoT sensors, access-control readers.
• Energy and charging: photovoltaic inverters, converters, charging stations for electric vehicles.
• Outdoor displays: display panels and interactive kiosks.

🔧 From the mast to the meeting room

On a pole or a wall: sealed radio units

A small cell works outdoors, in rain, snow and heat, so its cover has to seal as well as shield, and many shielding materials make poor weather seals. A conductive silicone EMI gasket does both in one part: 40 to 110 dB depending on the filler, −55 °C up to +125 °C or +200 °C, and sealing to IP65, IP66 or IP67 when the groove and the compression are right. Frequency matters too. As it rises, the wavelength shrinks, and a seam that did no harm on older equipment can behave like a slot antenna: one more reason to run the gasket round the whole cover without a break.

At street level: cabinets and their doors

A cabinet door closes on a frame that is never quite flat. A wire mesh gasket, knitted from metal wire, follows the frame and gives over 100 dB depending on the alloy and the frequency. Mesh on its own keeps out dust at most. For a cabinet that stands in the street, ask for the combined version, mesh bonded beside a sponge seal, which gives environmental sealing up to IP65. The wire (Monel, tin-plated copper-clad steel, stainless steel) is matched to the metal of the frame.

In the equipment room: racks, shelves and plug-in units

Indoors, the problem changes: units slide in and out of 19-inch racks, and each time one goes back, contact has to return along its whole edge without a hard push. That is the job of contact finger strips in beryllium copper, which reach up to 100 dB at 25 % compression and are fixed by clip, adhesive, solder or rivet. The sliding movement wipes the contact surfaces as it goes. Fingers do not seal, which is no drawback in a room.

Indoors, in plastic housings: gateways, controllers, readers

Routers and gateways put several radios and fast digital logic into one light plastic case, and plastic shields only once it carries a conductive coating. On such housings, as on any thin cover, little force is available to close the joint. Conductive fabric gaskets, a foam core wrapped in conductive fabric (fabric-over-foam, FOF), compress with very little force and are rated UL94-V0. They are fitted with their adhesive backing and can be cut to connector shapes (I/O, D-SUB). They are indoor gaskets: −10 °C to +110 °C, down to −40 °C depending on the reference.

Radio units and converters: heat out through the wall

A housing closed against rain lets no air through, yet a radio unit or a power converter still has heat to lose. A pad of thermal interface material fills the gap between the hot component and the wall or the heat sink, so that the heat leaves by conduction: 3 or 5 W/m·K, from 0.3 mm thick, up to 15 mm in the 3 W/m·K grade. The pads are silicone: soft, electrically insulating, rated UL 94 V-0, for use from −40 °C to +220 °C.

📐 EN 50121, ETSI EN 301 489, CISPR 32: which text for which equipment

The text that applies depends on what the equipment is. If it contains a radio, it comes under the Radio Equipment Directive 2014/53/EU, whose essential requirements cover safety and health, electromagnetic compatibility and the efficient use of the radio spectrum. The ETSI EN 301 489 series is the EMC standard for radio equipment and services: common emission and immunity requirements in Part 1, conditions specific to each type of radio equipment in the other parts. For multimedia equipment supplied at no more than 600 V, CISPR 32 (EN 55032 in Europe) sets the emission requirements, in two classes, A and B; its stated aim is to protect the radio spectrum from 9 kHz to 400 GHz. On the railway, the reference is EN 50121, Railway applications – Electromagnetic compatibility, which the IEC publishes with the same part titles as IEC 62236: Part 3-2 deals with apparatus on rolling stock, Part 4 with signalling and telecommunications apparatus.

Each of these texts is applied to the finished product. The gasket's part is to keep the housing electrically closed at its joints, and in that way it contributes to the compliance of the equipment. With the quote we send the material data (shielding effectiveness, temperature range, filler or alloy, flammability rating) so that you can choose the material and confirm it in your own tests. The EMC Directive 2014/30/EU and the generic standards IEC 61000-6-2 and IEC 61000-6-4 are presented on our page on EMC for industrial control cabinets.

🛠️ Tell us where it will be installed

The same electronics will not take the same gasket on a lamp post and in a server room. Tell us where the unit goes (indoors, under shelter, fully exposed), what the housing is made of and how it is finished, the section of the groove or the flange, how often the cover is opened, the IP rating you are aiming for and the frequencies that concern you. We reply with the reference that matches, as profile, cut gasket, strip or pad, and its datasheet comes with the quote. Prototypes, small series and series are all handled.

🤝 ElectroDome in practice

• Shielding gaskets and thermal pads from a single supplier, in Paris, with answers in English or French.
• Three sample pieces to try on your own housing.
• Traceable batches, checked before they are shipped.
• Figures given as indicative, then confirmed on the quote for the reference proposed.

❓ Frequently asked questions

What is EN 50121?

The European series of EMC standards for railway applications. It runs from the emission of the whole railway system to the outside world (Part 2) to apparatus on rolling stock (Part 3-2), signalling and telecommunications apparatus (Part 4) and fixed power supply installations (Part 5).

What is CISPR 32?

The international standard that sets the emission requirements for multimedia equipment with a rated supply voltage of up to 600 V. Its European counterpart is EN 55032.

What is ETSI EN 301 489?

A multi-part EMC standard for radio equipment and services. It was prepared as one voluntary means of meeting the essential requirements of the Radio Equipment Directive.

Can your gaskets go into equipment assessed to EN 50121, CISPR 32 or ETSI EN 301 489?

Yes: they are designed for EMC and can contribute to the compliance of the equipment. These standards are applied to the finished product, so you confirm the result in your own tests, with the material data we send.

Does an EMI gasket also keep water out?

It depends on the gasket. Conductive silicone shields and seals, to IP65, IP66 or IP67 when the groove and the compression are right; knitted mesh bonded beside a sponge seal gives up to IP65. Finger strips and fabric-over-foam gaskets only shield: they go indoors, or behind a separate weather seal.

Can I try a sample on my housing first?

Yes: 3 pieces of the reference proposed. Availability and lead time depend on the reference and are given on the quote.