Square D QBMIK Circuit Breaker Mechanical Interlock

Product Description

The SQUARE D QBMIK is a mechanical interlock accessory designed for use with circuit breakers. It provides a physical linkage that prevents two breakers from being in the ON position simultaneously, a function critical in transfer switch applications, alternate source switching, and generator tie-in scenarios. Licensed electricians and panel technicians install this accessory to enforce mutual exclusion between two power sources at the breaker level, reducing the risk of backfeed and code violations. The QBMIK weighs 0.35 pounds and measures 8 inches in length, 4.8 inches in width, and 0.5 inches in height.

This mechanical interlock is suited for residential and light commercial electrical panels where dual-source switching is required. Typical applications include main and generator breaker pairs in load centers, where the interlock ensures only one source energizes the buss at a time. It installs directly onto compatible SQUARE D circuit breakers without requiring additional hardware beyond the unit itself.

Key Features

• Enforces mutual exclusion between two circuit breakers to prevent simultaneous ON positions
• Supports generator tie-in and transfer switch configurations at the breaker level
• Compact form factor: 8 inches long, 4.8 inches wide, 0.5 inches high
• Lightweight at 0.35 pounds for easy handling during panel work
• Sold as a single-unit package (Pkg Qty: 1)

Compatibility

Designed for use with SQUARE D circuit breakers as an OEM-style mechanical interlock accessory. Refer to the SQUARE D product documentation to confirm compatibility with the specific breaker model in your panel before ordering.

Installation Notes

Installation should be performed by a licensed electrician in accordance with NFPA 70 (NEC) requirements. De-energize the panel and verify the absence of voltage with a calibrated meter before beginning work. Follow the manufacturer's installation instructions for attaching the interlock to the breaker handles. Do not modify the interlock or use it with breakers outside of the specified compatible product family.