The TQD22175 Circuit Breaker is a 175-amp, 2-pole, molded-case breaker that was widely used in residential, commercial, and light industrial applications. While it is no longer manufactured, it remains relevant for replacement and retrofit purposes. This guide outlines its features, common uses, and technical specifications for those working with existing panels that require a direct replacement.
Obsolescence and Current Use
Over time, the original manufacturer officially discontinued the TQD line. Therefore, the TQD22175 Circuit Breaker now serves primarily as a replacement part for systems originally designed for it. Avoid using it in new construction or in installations where newer alternatives exist.
Common Application: Solar Main Breaker Derating
During its final decade before being discontinued, the TQD22175 Circuit Breaker was commonly used in residential solar installations for main breaker derating. When homes were retrofitted with solar panels, electricians frequently reduced the main breaker amperage to comply with NEC guidelines, especially the 120% rule. The 175-amp rating made this breaker a frequent choice when derating from a 200-amp main.
Termination Options for the TQD22175 Circuit Breaker
The TQD22175 Circuit Breaker offered several different termination configurations, allowing for flexible installation based on panel design:
- Lugs on both the Line (ON) and Load (OFF) sides
- Lugs on the Line Side and bussing on the Load Side
- Bussing on both the Line and Load Sides
- Bussing on the Line Side and lugs on the Load Side
This variety made it easy to adapt to a wide range of panel layouts and retrofit situations. In addition, its modular connection styles helped reduce installation time in tight retrofit scenarios.
Electrical Ratings and Specifications
- Amp Rating: 175 Amps
- Poles: 2
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Voltage Rating: 240 Volts AC maximum
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Interrupting Rating (AIC): 10,000 Amps at 240V AC.
- The Hi-Break counterpart, the THQD22175, carries a rating of up to 22,000 Amps at 240V AC.
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Trip Unit: Thermal-magnetic (provides protection from both overloads and short circuits)
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Mounting Style: Typically bolt-on
- Breaker Type: Molded-case circuit breaker (MCCB)
How the TQD22175 Circuit Breaker Functions
The TQD22175 uses a thermal-magnetic trip mechanism:
- Thermal Protection (Overload): A bimetallic strip bends when exposed to sustained overcurrent, eventually tripping the breaker if unsafe levels persist.
- Magnetic Protection (Short Circuit): A magnetic coil responds immediately to sudden surges in current, tripping the breaker almost instantaneously to limit damage.
As a result, it protects against both long-term overcurrent and sudden faults. This dual-functionality allows the TQD22175 Circuit Breaker to protect against circuits that may experience both long-term overcurrent and sudden faults.
Situations Where It Was Commonly Used
- Residential Solar Retrofits: Especially for main breaker derating.
- Commercial Panelboards: For circuits supporting lighting, HVAC, or general branch circuits.
- Light Industrial Settings: Where mid-range ampacity was required for equipment like compressors, small motors, and machinery.
- Panel Upgrades: Moreover, it proved useful during retrofit projects where existing infrastructure required a breaker with specific form factor compatibility.
TQD22175 Circuit Breaker Installation and Compatibility Considerations
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Panel Compatibility: Always match the breaker to panels designed to accept the TQD frame. Always verify compatibility before installation.
Replacing a discontinued breaker like the TQD22175? Make sure your install is solid with our guide to selecting and installing the right circuit breaker mounting hardware. - Conductor Sizing: Proper conductor size is essential based on ampacity; follow NEC guidelines.
- Torque Specifications: Tighten terminal screws according to the manufacturer’s recommended torque values to prevent overheating or arcing.
- Environmental Conditions: Install in enclosures suitable for the surrounding environment. Manage moisture, heat, and dust appropriately for reliable performance.
Dealing with outdated electrical infrastructure? Learn how to navigate risks and replacements in our guide to legacy Federal Pacific Electric breakers.
Maintenance and Safety
- Routine Inspections: Look for signs of overheating, discoloration, loose terminals, or corrosion.
- Breaker Reset: After a trip occurs, switch the breaker fully to OFF before resetting it to ON.
- Testing: In some facilities, professionals or technicians manually test breakers to verify performance.
Conclusion
In summary, the TQD22175 Circuit Breaker remains a relevant legacy solution. The TQD22175 is a legacy circuit breaker that served reliably in various settings, particularly in residential solar upgrades and commercial panels. Although discontinued, The breaker continues to play a significant role in panel replacement and system maintenance. Electricians and facility managers working with older infrastructure benefit from understanding the TQD22175 Circuit Breaker's specs and use cases.
Working with discontinued breakers like the TQD22175 often involves real-world challenges that go beyond the spec sheet. For peer advice and field-tested solutions, visit the ECN Electrical Forum. Electricians and contractors on the forum actively share sourcing tips, discuss compatibility, and recommend safe installation practices for legacy equipment.
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