Square D QOU360 Miniature Circuit Breaker

While both series offer reliable thermal-magnetic overcurrent protection, their physical mounting methods are entirely different. QO breakers feature a plug-on design for bus bar connections in standard QO load centers. The QOU series, including this model, is a unit-mount breaker built specifically for DIN rail, surface, or flush mounting in control panels and OEM equipment.

No. Because it relies on a unit-mount and feed-thru wiring configuration rather than a plug-on jaw connection, it cannot be installed in standard residential QO or Homeline load centers. It is strictly designed for OEM enclosures, control systems, and independent DIN rail mounting.

Yes, the unit-mount design of this circuit breaker is naturally compatible with standard 35mm DIN rail systems often found in industrial automation enclosures. It can also be flush or surface mounted using compatible Square D mounting feet, offering high flexibility for custom panel builders.

This breaker accepts aluminum or copper conductors from 14 AWG to 2 AWG. Because it utilizes a feed-thru connection, both the line and load wires are secured directly into the box lugs. Electricians must ensure the wire is stripped to the proper length and the terminal screws are torqued precisely to the manufacturer specification printed on the breaker to prevent hazardous high-resistance connections.

While primarily used in 120/240V alternating current panels, this breaker is fully tested and UL-listed for 48V direct current systems, making it suitable for certain battery banks, telecommunications, or low-voltage control circuits. Note that the short-circuit interrupting capacity drops from 10kA in standard AC applications to 5kA when deployed in a DC system.

The breaker uses a dual-mechanism system. A bimetallic thermal element gradually heats and trips the breaker during sustained overloads, preventing wire damage. Meanwhile, an internal electromagnet responds instantaneously to high-level short circuits. The internal toggle is trip-free, meaning the breaker will safely interrupt the circuit even if the handle is physically held in the ON position.

Yes, like many miniature breakers from Schneider Electric, this QOU model features a Visi-Trip window. When the breaker trips due to an overload or short circuit, a high-visibility red indicator flag appears in the window, allowing operators to quickly identify the tripped circuit in a crowded control panel.

No. Breaker mounting profiles and DIN rail fitments can vary between manufacturers. If you are replacing a faulty Square D QOU breaker in an existing control panel, you must use an exact QOU replacement to ensure safe physical fitment and maintain the UL listing of the enclosure.