Merlin Gerin Masterpact NW10 H1 4-Pole 1000A Circuit Breaker

Schneider Electric / Merlin Gerin Masterpact NW10 H1 4-Pole 1000A Air Circuit Breaker

The Masterpact NW10 H1 is a 1000 A, 4-pole air circuit breaker designed to keep low-voltage power systems safe in challenging industrial, maritime, and commercial environments. This Masterpact NW10 H1 is built to handle high short-circuit levels, like those that happen with parallel transformers or strong motor loads, without losing its cool.

The Masterpact NW10 H1 4-pole 1000 A breaker is a heavy-duty air circuit breaker that won’t let you down, even when the system is under a lot of stress. It combines the rich history of Merlin Gerin with the engineering of Schneider Electric, so your panel feels safer, stronger, and easier to trust every time you put the Masterpact NW10 H1 in or take it out.

Model Details:

• Product Series: Masterpact NW
• Frame Rating: NW10 (1000 A at 40°C / 50°C Marine rating)
• Performance / Breaking Level: H1 (65 kA at 415/440V AC)
• Number of Poles: 4-Pole (4P / 4-Pin) with Left-side Fully Rated Neutral
• Historical Legacy Brand: Merlin Gerin (100% backward compatible with current Schneider Electric Masterpact NW series)

The Masterpact NW10 H1 breaker has four poles; thus, it protects the three phases and changes the neutral. This is crucial for safety, unbalanced loads, and delicate electronics. The drawout variants make things easier for maintenance crews since they can isolate, test, and replace the breaker without having to move the busbars or power lines. The fixed versions, on the other hand, keep things small and cost-effective when regular withdrawal isn’t needed.

The Masterpact NW10 H1 feels like the “heart” of the switchboard when it’s working. It silently carries 1000 A at 40 °C and is always ready to fix problems in a few milliseconds if something goes wrong. The Masterpact NW10 H1 becomes a smart protection device when used with Micrologic electronic trip units. It provides accurate protection, metering, and communication, so you can see and control what your power system is doing instead of just guessing.

Technical Specifications

Product Features:

• 1000 A rated current at 40 °C for continuous duty, perfect for main incomers and big outgoing feeders
• 4-pole setup (3P + N), with the option of having the neutral on the right or left, depending on the specific catalog number
• H1 performance level with a breaking capacity of 65 kA at 440 V AC, good for networks with a lot of faults
• The frame is made for 690 V AC operational voltage and 1000 V AC insulation voltage, which gives LV systems a lot of room to work with
• You can choose a fixed or drawout “basic frame” without a trip unit. It can be connected with Micrologic control units to fit your protection philosophy.

When reliability is important, such when downtime hurts, panels are far from home, or someone’s reputation depends on the breaker closing and opening at the right moment, engineers choose to choose the Masterpact NW10 H1. When things become tough, having a Masterpact NW10 H1 in the middle of the board gives you a quiet sense of confidence that is hard to put into words.

Terminal Allocations & Wiring Schematic Overview

• Main Power Terminals (1/L1, 3/L2, 5/L3, N/Left): Designed for direct connection to copper busbars with standard IEC 4-hole pad configuration (NPS pattern).
• Secondary Control Block (Auxiliary Block A, B, C, D):
  • Block A (Terminals 11–14, 21–24): OF1 & OF2 Standard Open/Closed Breaker Status Indication.
  • Block B (Terminals 31–34, 41–44): OF3 & OF4 Additional Auxiliary Indication Contacts.
  • Block C (Terminals 81–84, 184): SDE Fault Trip Indication Contact & Earth-Fault reset.
  • Block D (Terminals C1–C2, C11–C12, D1–D2): Remote Opening Coil (MX), Remote Closing Coil (XF), and Undervoltage Release (MN).
  • Motor Mechanism Terminals (M1, M2, B1, B2): Spring Charging Gear Motor power input (24V–250V DC / 110V–440V AC).

Marine & Industrial Applications

• Marine Main Switchboards (MSB): Primary generator incomers (up to 750kVA / 1000A generators) and bus-tie sectionalizers on commercial vessels, tankers, and workboats.
• Emergency Switchboards (ESB): Essential service distribution and emergency generator changeover switchgear.
• Offshore Drilling & FPSO Units: 440V/690V high-density motor control center (MCC) main feed protection against high prospective fault levels.
• Industrial Infrastructure & Data Centers: Critical feeder protection, UPS bypass lines, dual-transformer automated transfer switches (ATS), and industrial manufacturing switchboards.

Frequently Asked Questions

Can a Merlin Gerin Masterpact NW10 H1 breaker be replaced directly with a Schneider Electric Masterpact NW10?

Yes. Schneider Electric rebranded the Merlin Gerin Masterpact series without modifying frame physical dimensions, terminal spacing, cradle interlocking, or auxiliary plug allocations. A Schneider NW10 H1 drawout breaker slides directly into an existing Merlin Gerin NW10 cradle.

What is the technical difference between Masterpact NW10 H1 and N1 ratings?

The difference lies in short-circuit interrupting capacity. The NW10 N1 rating is 42 kA at 440V AC, whereas the NW10 H1 rating provides 65 kA at 440V AC. The H1 rating is required for heavy industrial and marine main switchboards where multiple generator sets operate in parallel.

Is the 4th pole (Neutral) on the Masterpact NW10 fully rated for 1000A?

Yes, standard 4-pole Masterpact NW breakers feature a 100% rated neutral pole located on the far left, capable of carrying the continuous 1000A rating to safely accommodate non-linear loads and triplen harmonic currents without thermal overloading.

Which Micrologic trip units provide marine-compliant earth-fault protection?

The Micrologic 6.0 A (Ammeter) and 6.0 E (Energy) trip units feature fully adjustable selective ground-fault protection matching class requirements for marine IT/TN-S network grounding schemes.