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White Schneider Electric DIN-rail miniature circuit breaker, two-pole toggle, screw-clamp terminals

Schneider Electric

Schneider Electric M9F42240 IEC Miniature Circuit Breaker 40A 2P C Curve

SKU CH-B32A-4F46A

Two-pole thermal-magnetic breaker rated 40 A, C-curve, 14 kA interrupting at 120/240 V AC with screw-clamp terminals for 18-2 AWG wire on DIN rail

  • Protects branch circuits with 40 A thermal-magnetic trip
  • Handles high fault currents up to 14 kA at 120/240 V AC
  • Accepts wire sizes from 18 AWG to 2 AWG via screw-clamp terminals
  • Mounts on standard DIN rail for quick panel installation
  • Meets UL 489 safety standard for reliable operation

40 A two-pole C-curve breaker

The Schneider Electric M9F42240 is a DIN-rail miniature circuit breaker rated at 40 A with two poles and a C-curve thermal-magnetic trip. It provides branch-circuit protection for loads with moderate inrush current in commercial and light-industrial panels.

14 kA interrupting at 120/240 V AC

The breaker carries a maximum AIR rating of 14 kA at 120/240 V AC and meets UL 489 requirements. It is not rated for DC applications, so it must only be used on alternating-current circuits within the stated voltage range.

18 AWG to 2 AWG screw-clamp terminals

Connection is made through screw-clamp terminals that accept solid or stranded conductors from 18 AWG up to 2 AWG. Installers must verify that the conductor size falls within this window to ensure a secure, code-compliant termination.

Highlights

  • Protects branch circuits with 40 A thermal-magnetic trip
  • Handles high fault currents up to 14 kA at 120/240 V AC
  • Accepts wire sizes from 18 AWG to 2 AWG via screw-clamp terminals
  • Mounts on standard DIN rail for quick panel installation
  • Meets UL 489 safety standard for reliable operation

Specifications

BrandSCHNEIDER ELECTRIC

Questions about this item

Should I pick the 40 A 2-pole C-curve or a different rating for my branch circuit?

Choose the 40 A rating when your branch circuit is designed for 40 A protection; the C-curve suits general mixed loads, while a B-curve would trip faster on inrush and a D-curve would tolerate higher surges.

What does the 14 kA interrupting rating mean once the breaker is installed in a panel?

It means the breaker can safely clear a short-circuit current up to 14 kA at 120/240 V AC without damage, so the available fault current at the panel must not exceed that value.

Is the screw-clamp terminal compatible with standard DIN-rail mounting and what wire sizes does it accept?

Yes, it mounts on a standard DIN rail and the screw-clamp terminals accept solid or stranded copper from 18 AWG up to 2 AWG.

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