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Siemens BL series 20A three-pole miniature circuit breaker, bolt-on mount, grey toggle, compact rectangular form

SIEMENS

SIEMENS B320H Miniature Circuit Breaker BL 20A 3 Pole 240V AC 22kA

SKU CH-K4M0-1G1YC

Three-pole miniature circuit breaker rated 20 A at 240 V AC with 22 kA interrupting capacity for Siemens P1 panelboards

  • 20 A rating protects standard three-phase circuits
  • 22 kA interrupting capacity handles high fault currents
  • Bolt-on mounting fits Siemens P1 panelboards directly
  • Three-pole design breaks all phases simultaneously
  • 240 V AC rating matches common commercial supply

Siemens B320H Circuit Breaker Overview

The Siemens B320H is a BL series miniature circuit breaker rated at 20 amps with three poles for 240V AC systems. It provides standard overcurrent protection for commercial and residential electrical panels. The unit features a bolt-on mounting style and toggle actuator for secure installation in compatible load centers. Electricians and facility managers use it for branch circuit protection in three-phase applications.

Interrupting Capacity and Voltage Limits

This breaker delivers a maximum AIR rating of 22kA at 240V AC, defining its short-circuit interrupting capability. It carries no DC voltage rating, restricting use to alternating current circuits only. The frame size is 125A/BLH, setting the upper boundary for the breaker family. Terminal connections accept a minimum of 12 AWG aluminium or 14 AWG copper conductors for safe termination.

Bolt-On Installation and Panel Compatibility

Installation requires a Siemens P1 panelboard or load center, as the bolt-on design mates directly with that series bus structure. The three-inch length and width fit standard BL pole spacing, while the four-inch depth clears typical enclosure gutters. Misalignment with non-P1 bus bars is the most common error, followed by undersized lug torque on aluminium wire. Verifying the panel series before mounting avoids rework.

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Price $448.99
Pricier than about 90% of the 1,135 comparable items (median $54.99).

Specifications

Product
Brand nameSIEMENS

Questions about this item

Should I choose the 20 A version or a different amperage for my three-phase circuit?

Choose the 20 A rating when your load calculation and upstream protection require exactly 20 amperes per pole; the breaker is offered in this single current rating for the BL series frame.

What does the 22 kA rating mean once the breaker is installed in a panel?

It means the breaker can safely interrupt up to 22 000 amperes of prospective fault current at 240 V AC without damage, protecting downstream wiring and equipment.

Does the bolt-on mounting work with any 240 V panel or only specific Siemens models?

The bolt-on design is made for Siemens P1 panelboards and load centers; it will not fit panels that require plug-in or DIN-rail mounting styles.

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