Overview
The Square D QO370 is a 3-pole standard-trip plug-on circuit breaker designed for overcurrent protection in commercial and industrial electrical distribution systems. This unit is rated 70 A at 240 VAC and delivers 10 kA breaking capacity. QO thermal magnetic circuit breakers provide overcurrent protection and switching on ac and dc systems with an overcenter, trip-free toggle mechanism and VisiTrip trip indication.
Key Features
- Thermal/magnetic trip mechanism with 10 kA interrupt rating at 240V
- Visi-Trip red indicator flag for fast visual identification of tripped circuits
- Plug-on mounting style for installation in Square D QO load centers, NQ panelboards, and Speed-D switchboards
- Compact 3/4 inch width design for small system footprint
- Accepts 8 to 2 AWG copper or aluminum wire with box lug terminals
- Available with factory-installed accessories including shunt trips, auxiliary switches, and alarm switches
Technical Specifications
The QO370 combines reliability with industry-standard ratings for heavy-duty circuit protection applications.
- Amperage: 70A
- Voltage: 240V AC
- Poles: 3 (three-phase)
- Breaking Capacity: 10 kA at 240V
- Trip Type: Thermal/Magnetic (common trip)
- Mounting: Plug-on (snap-in)
- Wire Size: 8 to 2 AWG
- Operating Temperature: 40°C rated
- Dimensions: 2.91 in L × 2.25 in W × 3.12 in H
- Frequency: 50/60 Hz
- Certifications: UL Listed under UL File E84967 and CSA Certified under CSA Master Contract 153555
Typical Applications
Built to handle heavier 70-amp loads, this three-pole miniature circuit breaker delivers standard overcurrent protection for commercial and industrial environments. Common uses include:
- Motor and machinery circuit protection
- HVAC and refrigeration system panels
- Industrial control and automation cabinets
- Commercial load center feeder distribution
- DC system protection (per UL 489 listing)
Compatibility & Replacements
Compatible With
- Square D QO load centers and enclosures
- Square D NQ panelboards
- Schneider Speed-D switchboards
- Standard 3/4-inch QO mounting rails
- 50/60 Hz AC and DC electrical systems
Replaces / Drop-In Replacement For
The QO370 is a direct replacement for existing Square D QO370 units in QO-series load centers. When upgrading or replacing failed 70A 3-pole breakers in QO enclosures, verify mounting compatibility with your existing panel specification sheet. Verify compatibility with your system integrator before ordering if replacing breakers in non-standard applications.
Works With
- Square D QO product line
- Standard 35mm DIN rail mounting systems (indirect, via QO carrier)
- Modular industrial distribution systems
- Stand-alone AC/DC protection circuits
