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Free Shipping Over $99
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Siemens Q345 Miniature Circuit Breaker
- 45A
- 3 Pole
- Plug-On
Siemens
Q345
Miniature Circuit Breaker
Brand
Siemens
SKU
Q345
Quantity
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Siemens Q345 - 45A 3 Pole Miniature Circuit Breaker
New
Quantity
Quantity
Siemens Q345 - 45A 3 Pole Miniature Circuit Breaker
New
Quantity
| Brand | Siemens |
|---|---|
| Part Number | Q345 |
| Series | Q |
| Amperage | 45A |
| Poles | 3 |
| Mounting Style | Plug-On |
| Voltage | 240VAC |
| Phase | 3 |
| AIC Rating | 10kA @ 240VAC |
| Frame Type | Q |
|---|---|
| Terminal Type | Lugs |
| For Use With | Siemens Panelboards, Siemens Load Centers |
| Wire Gauge | 8-6 AWG (Cu), 8-4 AWG (Al) |
| Max Wire | 4 AWG (Al), 6 AWG (Cu) |
| Min Wire | 8 AWG |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed |
| Available Options | Padlock Attachment, Shunt Trip, Auxiliary Switch |
|---|---|
| Standards | CSA C22.2 No. 5, UL 489 |
| Approval | CSA, HACR, UL |
| Temp Rating | 40C |
| Construction Features | HACR Rated, Common Trip |
Sold out
Quantity
Siemens Q345 - 45A 3 Pole Miniature Circuit Breaker
Re-Certified
Quantity
| Brand | Siemens |
|---|---|
| Part Number | Q345-R |
| Series | Q |
| Amperage | 45A |
| Poles | 3 |
| Mounting Style | Plug-On |
| Voltage | 240VAC |
| Phase | 3 |
| AIC Rating | 10kA @ 240VAC |
| Frame Type | Q |
|---|---|
| Terminal Type | Lugs |
| For Use With | Siemens Panelboards, Siemens Load Centers |
| Wire Gauge | 8-6 AWG (Cu), 8-4 AWG (Al) |
| Max Wire | 4 AWG (Al), 6 AWG (Cu) |
| Min Wire | 8 AWG |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed |
| Available Options | Padlock Attachment, Shunt Trip, Auxiliary Switch |
|---|---|
| Standards | CSA C22.2 No. 5, UL 489 |
| Approval | CSA, HACR, UL |
| Temp Rating | 40C |
| Construction Features | HACR Rated, Common Trip |
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Description
Built to handle 45-amp commercial loads, this three-pole QP family component provides standard 10kAIC thermal-magnetic protection. It mounts into compatible Siemens load centers and panelboards, acting as a functional substitute for legacy Murray MP345 units. The common trip mechanism ensures all phases disconnect simultaneously during a fault, while the HACR rating makes it suitable for HVAC motor applications.Specifications
| Brand | Siemens |
|---|---|
| Part Number | Q345 |
| Series | Q |
| Amperage | 45A |
| Poles | 3 |
| Mounting Style | Plug-On |
| Voltage | 240VAC |
| Phase | 3 |
| AIC Rating | 10kA @ 240VAC |
| Frame Type | Q |
|---|---|
| Terminal Type | Lugs |
| For Use With | Siemens Panelboards, Siemens Load Centers |
| Wire Gauge | 8-6 AWG (Cu), 8-4 AWG (Al) |
| Max Wire | 4 AWG (Al), 6 AWG (Cu) |
| Min Wire | 8 AWG |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed |
| Available Options | Padlock Attachment, Shunt Trip, Auxiliary Switch |
|---|---|
| Standards | CSA C22.2 No. 5, UL 489 |
| Approval | CSA, HACR, UL |
| Temp Rating | 40C |
| Construction Features | HACR Rated, Common Trip |
Product FAQs
8 answersWhich load centers accept the Siemens Q345?
It is designed for 3-phase Siemens PL, ES, Ultimate, and EQ series load centers, as well as compatible panelboards that accept Type QP breakers.
Can I use this to replace a legacy Murray breaker?
Yes, the Siemens Q345 is a direct, UL-listed replacement for the obsolete Murray MP345 circuit breaker.
How much panel space is needed for installation?
This 3-pole breaker requires three standard 1-inch spaces on the panel bus.
Is this breaker suitable for HVAC equipment?
Yes, it is HACR rated, meaning it is approved to handle the specific inrush currents of heating, air conditioning, and refrigeration motor loads.
What is required to use this as a back-fed main breaker?
To safely use this as a back-fed main, you must install a compatible hold-down kit, such as the Siemens ECMBR3, to secure the breaker to the panel bus.
Does this breaker feature a common trip mechanism?
Yes, it utilizes an internal common trip mechanism. If one phase experiences a fault, all three poles will trip simultaneously to disconnect power safely.
Can this be used in a single-phase panel?
No, this is a 3-pole breaker designed exclusively for 3-phase electrical systems and requires a 3-phase load center.
What is the difference between the Q345 and Q345H?
The Q345 has a standard interrupting rating of 10kAIC, while the Q345H is the high-interrupting version rated for 22kAIC.
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Reviews
Review summary
Customers rate this product 5.0 out of 5 based on 47 reviews.
Reviews Summary
Generated by AI from 91 most recent customer reviews
Last updated 8/1/25
Customers say these circuit breakers arrive quickly and match their specifications perfectly. Many reviews mention success finding hard-to-locate specialty breakers through this supplier. Common feedback includes praise for the accurate product descriptions, reliable shipping, and competitive pricing. While some note occasional stock limitations, users consistently report the breakers fit and function as intended.
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Rating
47 reviews
- CGCrocefissa G.Verified BuyerReviewingSiemens Q115 - 15A 1 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars9/18/26Quick delivery and great price.
The circuit breakers are at a great cost.
- JBJason B.Verified BuyerReviewingSiemens Q2150B - 150A 2 Pole Molded Case Circuit BreakerI recommend this productRated 5 out of 5 stars9/18/26Great experience
The product was exactly what I needed and it arrived on time.
- DQDon Q.Verified BuyerReviewingSiemens Q3100 - 100A 3 Pole Molded Case Circuit BreakerI recommend this productRated 5 out of 5 stars9/14/26Siemens breaker
Great customer experience, great prices and fast shipping... Definitely will be buying her again.
- CSChristopher S.Verified BuyerRated 5 out of 5 stars8/12/26Siemens 60
Perfect new condition
- GSGeorge S.Verified BuyerReviewingSiemens Q2150B - 150A 2 Pole Molded Case Circuit BreakerI recommend this productRated 5 out of 5 stars3/4/26Great service
Every time I call or go online you have the parts I'm looking for.