Siemens Q21540CTNC 15/40A Triplex Miniature Circuit Breaker
- 15/40A
- 4 Pole
- Plug-On
Siemens
Q21540CTNC
15/40A Triplex Miniature Circuit Breaker
Brand
Siemens
SKU
Q21540CTNC
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Siemens Q21540CTNC - 15/40A Triplex Miniature Circuit Breaker
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Description
Engineered for legacy applications, the Siemens Q21540CTNC is a Non-CTL triplex breaker. It houses a 40A double-pole center and two 15A single-pole outer circuits within a two-space form factor. Lacking a rejection clip, this plug-on unit is intended exclusively for pre-1968 Siemens load centers that do not accept modern CTL components. It serves as an exact substitute for the MP21540CTNC. Operating at 120/240VAC with a 10kAIC rating, it allows safe circuit expansion in older systems.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 (Non-CTL / Pre-1968) |
| Wire Gauge | 15A Poles: 14-6 AWG (Cu), 12-6 AWG (Al); 40A Poles: 8-6 AWG (Cu), 8-4 AWG (Al) |
| Max Wire | 6 AWG (Cu), 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 | Triplex |
|---|---|
| Available Options | Padlock Attachment |
| Accessories | Non-CTL (No Rejection Clip) |
| Standards | HACR, SWD (15A Poles), UL 489 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | HACR Rated, Insta-Wire |
Product FAQs
6 answersWhat does the "NC" suffix mean on the Q21540CTNC breaker?
The "NC" stands for Non-Circuit Total Limiting (Non-CTL). This breaker does not have a rejection clip on the bottom, allowing it to be installed in older, pre-1968 Siemens, ITE, or Murray load centers that lack CTL rejection features.
How many panel spaces does this quad breaker require?
This Type QT quad breaker provides four poles of protection but requires only two standard 1-inch spaces in a compatible load center.
What is the pole configuration for the 15A and 40A circuits?
The Q21540CTNC is configured with the 40A double-pole circuit on the inner (center) poles, which features a common trip. The two independent 15A single-pole circuits are located on the outer poles.
Can I use this Non-CTL breaker in a modern Siemens load center?
No. Modern Siemens panels are designed for CTL breakers and have physical rejection tabs. Because this is a Non-CTL breaker, it is strictly intended for older legacy panels. Modern panels require the standard CTL version of this breaker.
Is this a suitable replacement for older ITE or Murray quad breakers?
Yes. Siemens manufactures this breaker as the direct, UL-listed replacement for legacy ITE and Murray non-CTL quad breakers with a matching 15A and 40A configuration. Always verify that your panel label lists Type QT breakers as acceptable.
Does the 40A double-pole circuit feature a common trip?
Yes, the inner 40A circuit has a common trip mechanism. This ensures that both legs of the 240V circuit will disconnect simultaneously in the event of an overload or short circuit.
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