An Ex de control station in a glass fiber reinforced polyester (GRP) housing combines a flameproof Ex d operator chamber with an increased-safety Ex e wiring compartment, and is component-certified as a single unit for Zones 1, 2, 21 and 22 [S3][S4]. Carbon-loaded antistatic GRP keeps the enclosure non-sparking and UV-stable, while the inner Ex d contact block is factory sealed, so the end user terminates field wiring only into the Ex e side [S1][S4].
The two practical references to this family in the global catalog are the Pepperl+Fuchs GR series (large modular format, up to 68 operators, Ex db eb / Ex ib / Ex tb) and the LCP series (compact format, up to 4 operators, Ex de / Ex tb) [S1][S4][S5]. HARDO's HCS1P range is a third commercial implementation, with 14 published GRP sizes and IP65/66 sealing, built around the same Ex e enclosure with Ex d operator inserts [S2].
Why the Ex d contact block sits inside an Ex e box
The architecture is a deliberate split: a flameproof Ex d chamber is required wherever a switching device can produce an arc or hot gas during normal operation, and an Ex e chamber is sufficient for the wiring area because it only carries terminations and conductors [S3][S4]. Hardo's HCS1P description explicitly says the contact block, pushbutton, and isolator are Ex d certified, while the surrounding GRP shell is built to Ex e, giving the installer one Ex e enclosure with Ex d operators mounted through its walls [S2].
The Pepperl+Fuchs LCP datasheet formalises this as the marking string Ex II 2 GD Ex de IIC T6, T5, T4 Gb, with the dust extension Ex tb IIIC T80 °C, T95 °C, T130 °C Db, supported by ATEX certificate SIRA 13ATEX3059X and IECEx SIR 13.0021 [S4]. For an engineer comparing datasheets, the "de" mark is the giveaway that the device is a hybrid: "d" for the contact/operator cavity, "e" for the wiring cavity, sharing one common enclosure [S1][S4][S5].
Materials, surface resistance, and impact behaviour
Carbon-loaded GRP is the default material across Pepperl+Fuchs GR, Pepperl+Fuchs LCP, and HARDO HCS1P, and the datasheets call out three properties that matter in hazardous areas: antistatic (surface-resistive, to prevent brush discharge), UV-stabilized (for outdoor skids and offshore modules), and corrosion-resistant (so it can sit next to stainless steel without galvanic surprises) [S1][S2][S4]. The LCP datasheet specifies moulded self-colour black finish, one-piece solid silicone cover gasket, and M6 stainless steel socket cap head screws for cover fixing [S4].
Stainless steel is the alternative and the Pepperl+Fuchs SR series uses brushed AISI 316L with A4 grade fixings, with the same Ex de, Ex ib and Ex tb markings, and is additionally listed for Class I, Division 2 NEC markets [S1]. The trade-off is straightforward: GRP is lighter, non-sparking, and does not need painting, while 316L gives higher impact tolerance in heavy-mechanical areas and easier cleanability for hygienic or pharmaceutical zones [S1]. At a decision-rule level, most oil and gas and chemical plant outdoor installations are specified in GRP for weight and corrosion cost; stainless wins where the enclosure is hosed down, hit by trucks, or exposed to strong solvents [S1][S4].
Electrical ratings, terminals, and operator density
Across the GRP Ex de family, the published electrical ceiling is consistent: operating voltage up to 250 V AC and operating current up to 16 A, with a maximum terminal capacity of 2.5 mm² and a 2.5 mm² earth/grounding stud [S4]. The HARDO HCS1P, GR series, and LCP datasheets all constrain the operator menu to the same component-certified set: pushbuttons, illuminated pushbuttons, mushroom-head emergency stops, key-release pushbuttons, selector and control switches, control and load-break switches, LED indicators (including Ex i variants), potentiometers, and ammeters/voltmeters [S1][S2][S4].
Where the families diverge is operator density. The compact LCP is built for local control points: dimensions 110 × 110 × 101 mm up to 220 × 110 × 101 mm, with up to 4 operators and base-mounted contact blocks, weighing 0.9 to 2.0 kg empty [S4]. The GR series scales to 7 enclosure sizes and up to 68 operators per station, with a 10 mm design grid and a gridded DIN rail that lets the assembler position each operator precisely without drilling custom patterns [S1][S5]. HARDO's HCS1P sits between the two, offering 14 size codes from 80 × 80 × 55 mm up to 410 × 400 × 120 mm, with a hinge option on the cover and either polyamide or metallic cable glands on the face entries [S2].
Ingress, ambient, and temperature class
Protection degree is IP66 on the LCP, and IP65/66 across the HARDO HCS1P, and the published ambient range is –40 to 55 °C at temperature class T4, narrowing to –40 to 40 °C at T6 on the LCP, with –50 °C available on request [S2][S4]. The GR series datasheet quotes the same –40 to 55 °C operating window as the SR stainless series, so a designer can swap materials without redoing the thermal budget [S1]. Dust markings on the LCP are T80 °C, T95 °C, and T130 °C for surface temperature, aligned to the gas temperature class above [S4].
These limits interact with three real-world constraints. First, the operator density cap: more Ex d contact blocks in one enclosure means more internal heat, and at 4 operators on the LCP the T4 ceiling is fine, but pushing to 68 operators on a GR station with continuous loads may force a derate to T5 or T4 with restricted current per line [S1][S4][S5]. Second, the silicone gasket and the carbon-loaded GRP together tolerate the cold box (–40 °C) without embrittlement, which is why both Pepperl+Fuchs and HARDO publish the same low end on plastic enclosures [S1][S2]. Third, IP66 plus antistatic GRP together allow direct sunlight on a tropical platform without the surface-charge buildup that plain polyester would accumulate [S1][S4].
Selection rule set: GRP Ex de vs the alternatives
Decision rule 1, hazardous area classification: if the area is Zone 1 or Zone 2 gas plus Zone 21 or Zone 22 dust, all three GRP families are in scope; if the area is Division 1 NEC, the SR stainless line covers Class I, Division 2, but pure GRP GRP lines do not list Div 1 in the published approvals [S1][S4]. Decision rule 2, operator count: pick LCP for 1 to 4 operators (local stop/start stations, single isolators), HARDO HCS1P for 1 to ~10 operators in a mid-size box, and GR series when the station needs more than roughly 12 operators or mixed terminal compartments [S2][S4][S5]. Decision rule 3, environment: choose GRP for offshore, chemical, and weight-sensitive skids, and switch to 316L stainless (SR series) for heavy mechanical abuse, hygienic washdown, or solvent exposure [S1].
Decision rule 4, customisation: GRP control stations are commonly supplied factory-built, because drilling additional holes in a certified Ex enclosure invalidates the ATEX/IECEx certificate, so the configurator (number of operators, gland type, terminal count, label set) is the engineering deliverable, not the empty box [S2][S3][S5]. Inside a control station, the control panel component choices (contact blocks, signal lamps, terminals) are component-certified individually and then integrated under the same Ex de marking, which is why the datasheets list so many third-party pushbutton and ammeter brands as approved inserts [S2].
Failure modes and specification traps
The first trap is treating GRP as ordinary plastic. It is carbon-loaded specifically to be electrically dissipative, so painting it with a non-conductive topcoat, or replacing a lost cover screw with a zinc-plated steel part, breaks both the antistatic path and the corrosion story [S1][S4]. The second trap is mixing operator families: an Ex d contact block from vendor A and an Ex e mounting frame from vendor B may both carry their own certificates, but the combined assembly still needs a system-level Ex de certification on the enclosure, which is what the Pepperl+Fuchs LCP and GR datasheets hold with SIRA 13ATEX3059X and CML IECEx [S4][S5].
The third trap is gland selection. The LCP is shipped with one M20 polyamide stopping plug on face A and one M20 polyamide cable gland on face B as standard; metallic glands (brass or stainless) are needed where mechanical risk or EMC shielding matters, and that swap has to be captured in the project certificate, not made on site [S4]. The fourth trap is ambient derating: at T6 the LCP enclosure is limited to 40 °C ambient, while at T4 it accepts up to 55 °C, so a station in a sun-exposed Middle Eastern skid usually gets specified at T5 or T4 with a smaller continuous current per line, not at T6 [S4].
Applicable standards and what they actually require
The governing regime is ATEX 2014/34/EU for the European Union, paralleled by IECEx for international projects, with the LCP explicitly certified Ex II 2 GD (equipment group II, category 2, gas plus dust) [S4]. The "de" mark in that string is built on the IEC 60079 series, where Ex d covers flameproof enclosures capable of containing an internal explosion, and Ex e covers increased-safety terminals and housings where no arc or hot surface is expected in normal service; the GR.CS* type code on the GR series reflects this with "Ex db eb" in the latest certificate wording [S1][S5]. The IEC 60529-derived IP66 rating on the LCP is tested to EN 60529 [S4].
For dust, Ex tb IIIC T80/T95/T130 °C Db on the LCP aligns with the IEC 60079-31 dust-by-enclosure family, which is the reason the datasheet ties the dust surface temperature to the gas T-class above it [S4]. Customs Union TR approval RU C-DE B.00567 is listed on the LCP, which is the EAC Ex mark for the Eurasian Economic Union, so a station delivered into Russia or Kazakhstan is shipped with that certificate in the box [S4]. For the United States and Canada, the SR stainless line carries Class I, Division 2, while the GRP-only families (GR, LCP, HCS1P) are positioned for IECEx/ATEX zones rather than the NEC division system [S1][S2][S4].
Trackable next signals: the GR series datasheet lists CML IECEx, Europe CML ATEX, UK-Type Examination, MASC (South Africa), and an EU Declaration of Conformity issued by Pepperl+Fuchs, so a procurement engineer can verify the certificate chain for any specific GR.CS* part number against the issuing body's online register [S5]. LCP buyers can do the same with SIRA 13ATEX3059X and IECEx SIR 13.0021 [S4]. For projects that need to integrate mechanical and electrical packages, see how a related industrial skids comparison is laid out in hard chrome versus HVOF tungsten carbide wear coating decisions, which uses the same criteria-based comparison pattern for a different component class.
For component-level specifications, see angular contact bearing, and total station.