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Siemens Q21540CT2 15/40A Quadplex Miniature Circuit Breaker
- 15/40A
- 4 Pole
- Plug-On
Siemens
Q21540CT2
15/40A Quadplex Miniature Circuit Breaker
Brand
Siemens
SKU
Q21540CT2
Quantity
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Siemens Q21540CT2 - 15/40A Quadplex Miniature Circuit Breaker
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Description
Built for high-density residential applications, this 15/40A quad breaker supplies two distinct 240V circuits from a single two-pole space. The unit incorporates a 40A inner pair and a 15A outer pair, making it ideal for adding new loads to full panels. It installs into Siemens and Murray load centers equipped with CTL rejection features. This model replaces the MP21540CT2. With a 10kAIC rating and common trip functionality on both circuit pairs, it ensures reliable thermal-magnetic protection.Specifications
| Brand | Siemens |
|---|---|
| Series | QT |
| Amperage | 15/40A |
| Poles | 4 |
| Mounting Style | Plug-On |
| Voltage | 120/240VAC |
| Phase | 1 |
| AIC Rating | 10kA @ 120/240VAC |
| Frame Type | Q |
|---|---|
| Terminal Type | Lugs |
| For Use With | Siemens Load Centers (CTL), Murray Load Centers |
| Wire Gauge | 15A: 14-6 AWG (Cu) / 12-6 AWG (Al), 40A: 8-6 AWG (Cu) / 8-4 AWG (Al) |
| Max Wire | 4 AWG (Al) |
| Min Wire | 14 AWG |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed |
| Special Classification | Quadplex |
|---|---|
| Available Options | Padlock Attachment |
| Accessories | Common Trip (Factory Installed) |
| Standards | HACR Rated, SWD Rated (15A Poles), UL 489 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | HACR Rated, Common Trip, Insta-Wire |
Product FAQs
7 answersCan I install the Siemens Q21540CT2 in a Murray load center?
Yes. Siemens acquired Murray and officially lists the QT series as the UL-listed replacement for legacy Murray MH-T and MP quadplex breakers. Check your panel label to confirm it accepts CTL breakers.
How are the 15A and 40A circuits configured on the Q21540CT2?
This quadplex breaker features a 40A two-pole circuit on the inner poles and a 15A two-pole circuit on the outer poles. Both circuits operate independently of each other.
What does the CT2 suffix mean for installation?
The CT2 suffix indicates this is a Class CTL (Circuit Total Limiting) breaker. It features a rejection clip on the base that prevents it from being installed in panel slots not designed to accept tandem or quadplex breakers.
What are the lug wire size capacities for the 15A and 40A poles?
The 15A outer poles accept 14 to 6 AWG copper or 12 to 6 AWG aluminum wire. The 40A inner poles require larger conductors, accepting 8 to 6 AWG copper or 8 to 4 AWG aluminum wire.
Is the Q21540CT2 a direct replacement for the Murray MP21540CT2?
Yes. Siemens phased out the Murray brand and designated the QT series as the direct, UL-listed replacement for equivalent Murray MP and MH-T quadplex breakers, including the MP21540CT2.
Do the 240V circuits on this quad breaker feature a common trip?
Yes. Both the 15A outer circuit and the 40A inner circuit have internal common trip mechanisms. A fault on one leg of either 240V circuit will trip both poles of that specific circuit simultaneously.
How many panel spaces does the Q21540CT2 require?
This quadplex breaker provides two independent 240V circuits but only requires two standard one-inch panel spaces, making it ideal for maximizing capacity in crowded load centers.
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