Schneider Electric ZBZG156 Test Light Block 12 V

ZBZG156: single light block for the test light function, 12 V

The ZBZG156 is a Schneider Electric Harmony accessory described on its datasheet as a single block for the test light function. It belongs to the Harmony XB4 and XB5 ranges, it is compatible with integral LED and BA 9s lamp types, and it has a single wire connection. Seven Star LLC supplies the ZBZG156 in Oman and the GCC as an independent supplier in Muscat, usually to panel builders and maintenance teams working on indicator circuits with a lamp test.

On the datasheet generated on 8 Nov 2026 the ZBZG156 is not marked as discontinued. The datasheet is short, so this page is limited to what it states, and anything about wiring or the lamp test circuit of a particular panel should be checked against the panel drawings.

Environment and approvals for the ZBZG156

The datasheet gives an operating temperature of -25 to 70 °C and a storage temperature of -40 to 70 °C. Vibration resistance is 5 gn from 2 to 500 Hz, and shock resistance is 30 gn for 18 ms and 50 gn for 11 ms. The electrical shock protection class is Class I for Harmony XB4 and Class II for Harmony XB5 to IEC 60536.

The certifications listed are DNV, UL listed, Lloyd’s Register of Shipping, BV and CSA. The standards listed include IEC 60947-1, IEC 60947-5-1, IEC 60947-5-4, IEC 60947-5-5, UL 508, CSA C22.2 No 14 and JIS C 4520. Compare these with the project requirements before relying on any of them for this unit.

Where such blocks are found in Oman and the GCC

Lamp test circuits are specified on motor control centres, generator control panels, marine and offshore panels, and process control desks in oil and gas, power and water plants. The DNV, Lloyd’s Register and BV listings on the datasheet make the ZBZG156 relevant to marine style projects, as long as the approval needed is the one listed. Heat and dust are the usual enemies, and plastic blocks should be inspected for discolouration when a panel is opened.

Technical data of the ZBZG156

Supply voltages listed for the ZBZG156

The datasheet lists three rated supply voltage entries for the ZBZG156: 12 V AC/DC, 24 V AC/DC and 24 to 120 V AC/DC. The page title and the product name stress 12 V, but the other entries show that the block is described for use across several control voltages, so the actual voltage in your panel should be confirmed against the panel drawings before fitting.

The same listing shows compatibility with integral LED lamps and BA 9s lamp bases. That covers the two lamp styles used in this family of illuminated heads, and it explains why a single block can serve both older bulb-type stations and LED stations.

Handling and maintenance of the ZBZG156

Isolate the control circuit before touching any lamp or block, note the position and the colour of the wire, and fit the replacement this unit in the same position. After fitting, operate the test function and look for all lamps in the circuit lighting together. A lamp that stays dark points to a failed lamp or a broken wire rather than to the block.

Keep spares in their original packaging in a dry store. The storage range is wide enough for normal conditions, but plastic parts should not stay in direct sunlight on a Gulf site for long.

What a test light block is for

A test light function lets an operator check that the indicator lamps on a panel are working by pressing a test button, so a dark lamp is known to be failed rather than simply off. Whether the ZBZG156 is wired as the lamp test source in a given panel depends on the circuit design, and the datasheet gives no wiring diagram, so the circuit should be traced from the panel drawings before the part is chosen or replaced.

The block is classed as a single block with one wire, which is simpler than a block with a full contact assembly. That simplicity is the reason it is often kept as a spare: a failed test circuit is easy to restore if the same part is available.

Choosing a replacement for the ZBZG156

Because the block can be described in several ways, a replacement should be chosen from the old part label rather than the colour or the panel position. Check the part number, the supply voltage of the lamp circuit, the lamp type (integral LED or BA 9s) and the head family (XB4 or XB5). The shock protection class differs between the two families, with Class I for XB4 and Class II for XB5, so the earthing arrangement of the station is also part of the choice.

The net weight is 0.01 kg, and the body is plastic, which keeps it light enough to be carried as a stock spare for many stations.

Information to send with an RFQ for ZBZG156

The points below let us confirm the part number against the datasheet and check stock in one reply.

• Part number this unit and quantity.
• Photo of the old block and its label.
• Supply voltage of the lamp circuit.
• Lamp type: integral LED or BA 9s.
• Head family: XB4 or XB5.
• Approvals needed (DNV, BV, Lloyd’s Register, UL).
• Delivery location.

The old label is the best proof of a like-for-like match.

Documents and quotation

A copy of the Schneider Electric datasheet for the ZBZG156 is attached on this page for your technical file. It holds the electrical, mechanical and environmental values that are summarised above.

To request a quotation, send the part number and the quantity through the enquiry form and we will reply with availability and delivery terms. Seven Star LLC is an independent supplier and does not act for the manufacturer, so please compare the datasheet with your project requirements before you order.