Schneider Electric XB4BG21EX ATEX Key Selector Switch 2-Pos 1 NO

XB4BG21EX key selector switch for combustible dust areas

The XB4BG21EX is the ATEX-marked key selector in the Schneider Electric Harmony XB4 family: a 22 mm key switch with two stay-put positions at 90°, one normally open contact, and the same key number 455 used by its non-ATEX sibling XB4BG21. What makes it different is the approval data: the datasheet lists a dust zone of 21-22, the marking Ex tb IIIC, the directive 94/9/EC (ATEX) and the certificate reference INERIS 04ATEX9004U. Seven Star LLC supplies the XB4BG21EX in Oman and the GCC as an independent supplier based in Muscat.

This page restates the datasheet so that engineers can see where the ATEX variant departs from the standard unit, in life, temperature range and sealing, before they order.

XB4BG21EX technical specifications

How the XB4BG21EX operates

The key switch turns between two positions 90° apart and stays where it is put (stay-put operation). The datasheet gives the key withdrawal position as left-hand, so the key can only be removed in the left position. With key number 455 it shares a key with other XB4 key selectors of the same number, which can be useful when one operator should control several panels. Operating torque is 0.14 N.m NO changing electrical state.

XB4BG21EX compared with other key selectors

The four key selectors in this group differ in the number of positions, the return action, the contacts and the approvals, as the comparison below shows.

Contact data of the XB4BG21EX

For the electrical design take these values from the datasheet: 10 A conventional free-air thermal current, 600 V rated insulation voltage (pollution degree 3), 6 kV rated impulse withstand and a 10 A gG fuse for short-circuit protection. The contacts are silver alloy (Ag/Ni) and break slowly. Operational current depends on voltage and utilisation category, as listed here.

• 3 A at 240 V, AC-15, A600
• 6 A at 120 V, AC-15, A600
• 0.1 A at 600 V, DC-13, Q600
• 0.27 A at 250 V, DC-13, Q600
• 0.55 A at 125 V, DC-13, Q600
• 1.2 A at 600 V, AC-15, A600

Hazardous-area data and environment of the XB4BG21EX

This unit is given a degree of protection of IP65, with NEMA 13 and NEMA 4X also listed. The operating ambient range is -20–60 °C, narrower than the -40 to 70 °C of the standard XB4BG21, and the mounting hole is Fixing hole – diameter: 22.5 mm 22.3 +0.4/0 with a minimum fixing centre of ≥ 30 × 40 mm (support panel). The datasheet lists standards IEC 60079-0:2009, EN 60079-31:2009, IEC 61000-6-2 among others. Mechanical life is stated as 3,000,000 cycles. Impact protection is IK06.

Treat the datasheet marking as the starting point, not the whole assessment. Zone suitability also depends on the installation, the enclosure, the temperature class and the local rules, which the plant owner or competent person must verify.

Selection and installation of the XB4BG21EX

• Positions: 2 positions 90°, stay put.
• Contacts: 1 NO (terminal marking 13-14).
• Key: number 455, withdrawn at the left-hand position.
• Panel: 22.5 mm mounting hole in the datasheet standard version.
• Environment: matches the temperature range and sealing listed above.
• Area: dust zone 21-22 with the ATEX marking listed.

Fit this unit through a 22 mm hole and tighten the fixing as the datasheet specifies: 0.8–1.2 N.m. Terminals accept ≤ 2 × 1.5 mm² with cable end and ≥ 1 × 0.22 mm² without cable end, and screw heads take Philips no 1, pozidriv no 1 or flat 4 and 5.5 mm drivers. Keep the enclosure closed and the mounting hole as stated for the certified assembly.

At commissioning, test every key position with the control circuit energised, confirm that the key can only be withdrawn at the stated position, and record who holds the keys. Re-test the contact function after any rewiring.

Where the XB4BG21EX is used in Oman and the GCC

Dust-hazard locations such as grain handling, cement and mineral processing, and similar plants are typical for an ATEX-marked key switch. Heat and fine airborne dust are the reality in Oman, so check the lower operating range and clean the enclosure on schedule.

Plan the key schedule at the design stage: how many keys are issued, who signs for them and where spares are stored. Without that, the access control that the key switch offers exists only on paper.

Information to send with an RFQ for the XB4BG21EX

Send the part number XB4BG21EX, the quantity and the delivery location in Oman or the GCC. State the zone, the required marking and the ambient temperature at the installation. If you are replacing an installed unit, a photo of its side label or of the rear of the block helps us confirm that the reference is identical.

Documents and quotation

A copy of the Schneider Electric datasheet of this unit is attached to this page for download, and every value quoted here comes from that document.

For a quotation, use the RFQ form and quote XB4BG21EX together with the quantity and the destination. Seven Star LLC will come back with stock status and delivery time.