Skip to main content
Expedited shipping available at checkout

Siemens NGB3B050B Molded Case Circuit Breaker

  • 50A
  • 3 Pole
  • Bolt-On
Siemens NGB3B050B
Molded Case Circuit Breaker
Brand Siemens
SKU NGB3B050B
Select Item Condition
Earn 329 SuperPoints
  • 50A
  • 3 Pole
  • Bolt-On

Quantity

Bulk Pricing
Send your parts list for a volume quote.
Siemens NGB3B050B - 50A 3 Pole Molded Case Circuit Breaker

Siemens NGB3B050B - 50A 3 Pole Molded Case Circuit Breaker

Re-Certified

$329.99 No Stock

Quantity

Similar Items

Description

Delivering robust overcurrent protection, this 50A thermal-magnetic breaker comes with factory-installed load lugs for commercial systems. The Siemens NGB3B050B offers a 100kAIC interrupting rating at 240V and 25kAIC at 480Y/277V. This 3-pole MCCB bolts into Siemens P1, P2, and P3 panelboards. It features fixed long-time and instantaneous (LI) trip functions and is HACR rated for HVAC equipment. For facility upgrades, note this legacy frame is replaced by the newer Siemens 3VA51 series.

Specifications

Key specifications
Brand Siemens
Part Number NGB3B050B
Series NGB
Amperage 50A
Poles 3
Mounting Style Bolt-On
Voltage 240VAC, 480Y/277VAC, 600Y/347VAC, 125/250VDC
Phase 3
AIC Rating 100kA @ 240VAC, 25kA @ 480Y/277VAC, 14kA @ 600Y/347VAC, 14kA @ 125/250VDC
Fit and installation
Terminal Type Lugs
For Use With Siemens P1, P2, P3 Panelboards
Wire Gauge #14-1/0 AWG (Cu/Al)
Max Wire 1/0 AWG
Min Wire 14 AWG
Protection and operation
Trip Technology Thermal Magnetic
Trip Function Code LI
Trip Function Long-Time, Instantaneous
Trip Adjustability Fixed Thermal, Fixed Magnetic
Standards and features
Available Options Shunt Trip, Auxiliary Switch, Alarm Switch, Padlock Attachment
Accessories Load Side Lugs
Standards CSA C22.2 No. 5, HACR, UL 489
Approval CSA, HACR, UL
Temp Rating 40C
Construction Features HACR Rated, HID Rated, Reverse Feed, Trip-Free Mechanism

Product FAQs

8 answers
Which Siemens panelboards are compatible with the NGB3B050B circuit breaker?

This breaker is compatible with Siemens P1, P2, and P3 panelboards. It uses a bolt-on mounting configuration to connect directly to the panelboard bus.

What type of trip unit is installed in the NGB3B050B?

This breaker features a fixed thermal and fixed magnetic trip unit with Long-Time and Instantaneous (LI) protection. The trip settings are factory sealed and are not field-adjustable.

What are the acceptable wire sizes for the load terminals?

The factory-installed load lugs accept copper or aluminum conductors ranging from 14 AWG to 1/0 AWG.

Is the Siemens NGB3B050B rated for direct current applications?

Yes, this molded case circuit breaker is rated for DC systems. It supports up to 125/250VDC with an interrupting capacity of 14kA.

Can the trip unit on the NGB3B050B be replaced or upgraded?

No, the NGB frame uses a non-interchangeable trip unit. If your application requires different trip characteristics or amperage, the entire breaker must be replaced.

Are the load-side lugs included with this circuit breaker?

Yes, the NGB3B050B comes standard with load lugs. They are designed for terminating your branch circuit wiring directly to the breaker.

Can this breaker replace an older ITE NGB3B050B?

Yes. Siemens manufactures this breaker under the same catalog number previously used by ITE. It is a direct replacement for older ITE NGB3B050B circuit breakers.

What safety precautions are required when installing this bolt-on breaker?

Always de-energize the panelboard before installing or removing bolt-on breakers. Verify the power is off using a properly rated voltage meter before handling the bus connections or tightening the mounting hardware.

SuperClub

Join free. Get 500 SuperPoints.

Earn points on eligible purchases and redeem them at checkout.

100 SuperPoints = $1 off.

Warranties

60-Day Warranty

Your purchase includes 60 days of SuperBreakers warranty coverage.

Get a Quote

Don’t see what you’re looking for?

We source obsolete and hard-to-find parts every day.

Shipping

Free Shipping Policy

Parcel shipments with item value over $99 qualify for free economy shipping within the continental US. Please call to confirm special handling instructions. We do not charge a handling fee or require a minimum amount on any order. SuperBreakers does not ship on customer accounts.

Read our full shipping policy

Same Day Shipping

We strive to ship out your items the same day the order is placed. In rare circumstances SuperBreakers may reserve up to 5 business days to consolidate orders for complete shipment.

Expedited Shipments

Orders being shipped via Next Day Air, 2 Day Shipping or 3 Day Shipping must be received by 3 PM EST to guarantee same-day shipments. Expedited orders only ship on normal business days. Shipments will NOT be sent out on Saturdays and Sundays.

International Shipping

All International orders require a $1,000 minimum order threshold. Due to the special nature of these shipments, we require that these be placed with a SuperBreakers representative. Additional shipping and instructions will apply. All International Orders are Non-Cancel and Non-Refundable.

Reviews

4.5
Rated 4.5 out of 5 stars
Based on 8 reviews
Rating
Ratings
8 reviews
  • JH
    John H.
    Verified Buyer
    Reviewing
    Siemens NGB3B015B - 15A 3 Pole Molded Case Circuit Breaker
    I recommend this product
    Rated 5 out of 5 stars
    9/16/26
    480v breakers

    The breakers work great

  • BP
    Bland P.
    Verified Buyer
    Reviewing
    Siemens NGB3B100 - 100A 3 Pole Molded Case Circuit Breaker
    I do not recommend this product
    Rated 1 out of 5 stars
    7/22/26
    NO LUGS!!

    I ordered this breaker and it arrived with no lugs. It was advertised as new so we didn't open the box and check until the shutdown we needed it for. When we discovered the lugs were missing we sent an email requesting a set overnighted. We didn't get a response for a couple of days, at which point we had already ordered lugs from their competitor Simply Breakers. They asked for pictures and questioned weather we had ordered the correct breaker asking if we needed lugs on both sides. This is a panel breaker and their is only one configuration that I am aware of which is bolted to bus in panel and wires to the three lugs on the other side. I have never had to order lugs separately for this style of breaker. They asked for pictures of box and what was in it, of course at this point the breaker is already installed and the box is thrown away. I sent a receipt for the overnight lugs from Simply breakers and asked for whatever credit they could provide. I received crickets to date. I have never had a problem with an order in the past from super breakers, but they are to busy to even respond to my request so I will think twice before I order anything from them again. It will be my last option once all others have been exhausted. Use Simply Breakers they have better stock and service.

  • PF
    Paul F.
    Verified Buyer
    Reviewing
    Siemens NGB3B060B - 60A 3 Pole Molded Case Circuit Breaker
    I recommend this product
    Rated 5 out of 5 stars
    6/24/26
    Great service, quick shippin

    Need I say more.I have used SB. When we need it and need it quickly Always have what I need.

  • BP
    BJ P.
    Verified Buyer
    Reviewing
    Siemens NGB3B020B - 20A 3 Pole Molded Case Circuit Breaker
    I recommend this product
    Rated 5 out of 5 stars
    5/11/26
    NGB3B020B

    I recently purchased the NGB3B020B and I’m very satisfied with the quality and performance. The breaker feels solid and well-made, and installation was straightforward. It works exactly as expected and provides reliable protection for my electrical setup. Shipping was fast and the product arrived in excellent condition. I would definitely purchase from this seller again.

  • RS
    Radovan S.
    Verified Buyer
    Reviewing
    Siemens NGB3B050B - 50A 3 Pole Molded Case Circuit Breaker
    I recommend this product
    Rated 5 out of 5 stars
    3/9/26
    Absolutely amazing service.

    On Time