Schneider Electric 18856 NG125L 3P 80A D-Curve MCB

18856: Acti9 NG125L 3-pole 80 A D-curve miniature circuit-breaker

The 18856 is a Schneider Electric Acti9 NG125L three-pole miniature circuit-breaker rated 80 A with a D curve. The datasheet lists a breaking capacity of 50 kA Icu at 380–415 V AC and 100 kA at 220–240 V AC, thermal-magnetic tripping and clip-on mounting on a 35 mm DIN rail. Seven Star LLC supplies it as an independent supplier in Oman and the GCC for switchboard builders, electrical contractors and maintenance teams.

The title of the reference reads NG125 – circuit breaker – NG125L – 3P – 80A – D curve, which is the only decoding available: NG125L is the high-breaking-capacity version in the family, 3P the number of poles, 80 A the rating and D the tripping curve. The datasheet we downloaded is dated 8 Nov 2026 and carries a notice that the product was discontinued on 20 Oct 2026, with end-of-service planned for 30 Apr 2030.

Technical specifications of the 18856

Breaking capacity and system voltages for the 18856

Breaking capacity depends on the system voltage. The datasheet lists 100 kA at 220–240 V AC, 50 kA at 380–415 V AC, 40 kA at 440 V AC and 15 kA at 500 V AC, all to EN/IEC 60947-2. For DC it gives 36 kA at up to 375 V DC. The service breaking capacity (Ics) is 75 % of Icu on the AC values and 100 % on the DC value, so the breaker stays serviceable after a fault at those levels.

Compare the prospective short-circuit current at the point of installation with the figure for the voltage that applies, not the highest number in the table. On a 415 V three-phase system the relevant value is 50 kA, and the board design must also respect the busbar and enclosure ratings.

Selection checklist for the 18856

• Rating and poles: 80 A, 3P, to match the cable and the load.
• Curve: D, for high inrush loads; confirm against the load data.
• Breaking capacity: compare the fault level at the board with the Icu for your voltage.
• Network: AC or DC use, with the DC voltage limit of 375 V.
• Earth-leakage protection: a separate block is required if wanted.
• Lifecycle: discontinued notice on the datasheet; plan spares.

Typical uses of the 18856 in Oman and the GCC

NG125 breakers are used as feeder and main protection in distribution boards for commercial buildings, workshops, utilities and light industrial plant. The L version suits locations close to transformers, where fault levels are high, and sites with generator or DC supplies within the voltage limits listed.

In the region, large air-conditioning loads, pumps and motor circuits with high starting current are typical D-curve users. Thermographic inspection of the terminals during the summer peak is a cheap way to catch a loose termination before it fails.

Mounting, terminals and handling of the 18856

The breaker clips onto a 35 mm symmetrical DIN rail in a vertical position. It is 81 mm wide, which corresponds to nine 9 mm pitches, 103 mm high and 81 mm deep, and weighs 0.72 kg. The datasheet states that comb busbar and distribution block compatibility is not provided, so wiring is by cable into the terminals.

Tunnel terminals accept 16–70 mm² rigid or 10–50 mm² flexible conductors with a 20 mm strip length and a 6 N.m tightening torque. Use a calibrated torque screwdriver; loose terminals at this current level are a common source of heating. Integrated padlocking allows the breaker to be locked in the open position for isolation work.

Lifecycle status and spares planning for the 18856

Because the datasheet marks the 18856 as discontinued, planning matters. For an installed base, the practical steps are to count the breakers in service, buy spares while stock is available and ask us about a replacement series for new work. Mechanical durability is listed as 20000 cycles and electrical durability as 5000 cycles, which gives a basis for maintenance planning on frequently operated circuits.

The datasheet date of 8 Nov 2026 is the date of the downloaded document, and we have not checked it against later manufacturer notices. Send us the reference and we will confirm what is available for your quantity.

D curve and tripping behaviour of the 18856

The thermal-magnetic trip unit combines a bimetal element for overloads with a magnetic element for short circuits. The datasheet gives the magnetic tripping limit as 12 × In ± 20 %, which on an 80 A breaker corresponds to a threshold of about 960 A, with a tolerance band of roughly 770 to 1150 A. That is the figure to use in selectivity and cable-protection studies.

A D curve tolerates high inrush current, so it suits loads such as transformers, motors with large starting current and capacitive equipment. For ordinary resistive and mixed distribution circuits, a C curve is more common, and the choice should follow the load and the earth-fault loop impedance, not habit.

Information to send with an RFQ for the 18856

• Exact reference 18856 and quantity.
• System voltage, frequency and AC or DC use.
• Prospective fault level at the board.
• Existing breaker make and model if this is a replacement.
• Delivery location and project schedule.

Documents and quotation

The manufacturer datasheet for the 18856 is attached on this page and carries the specification summarised above. It also states the discontinuation notice described above. Check the revision date printed on it against your project documents before you rely on a figure.

Send us the reference 18856, the quantity and the delivery location, and Seven Star LLC will reply to your request. We are an independent supplier based in Muscat and we confirm availability and lead time per enquiry.