Eaton NB Series Molded Case Ci...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$5,378.24
Eaton NB Series Molded Case Circuit Breaker Trip Unit, Three-Pole, Fixed Thermal-Magnetic

Eaton NB Series Molded Case Circuit Breaker Trip Unit, Three-Pole, Fixed Thermal-Magnetic

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Model: NB3400PT

In Stock (leaves warehouse same day if ordered before 3pm ET)

$5,378.24
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Eaton NB Series Molded Case Circuit Breaker Trip Unit, Three-Pole, Fixed Thermal-Magnetic

The Eaton NB Series molded case circuit breaker trip unit is built for demanding commercial and industrial power distribution applications, delivering a 400 A amperage rating, a dual voltage rating of 600 Vac / 250 Vdc, and a 2000-4000A magnetic trip range in a rugged three-pole, UL 489 listed design. Configured with fixed thermal, fixed magnetic trip elements, this NB frame trip unit is engineered to provide dependable overcurrent protection with a 100 kAIC interrupt rating at 250 Vdc for critical distribution equipment.

Key Features

  • Amperage Rating: 400 A rated trip unit sized for demanding feeder and branch circuit protection.
  • Voltage Rating: 600 Vac, 250 Vdc dual rating for flexible AC and DC distribution applications.
  • Magnetic Trip Range: 2000-4000A adjustable magnetic trip setting for tailored overcurrent coordination.
  • Interrupt Rating: 100 kAIC at 250 Vdc for high fault-current withstand in demanding installations.
  • Trip Type: Fixed thermal, fixed magnetic trip elements deliver consistent, predictable overcurrent response.
  • Number of Poles: Three-pole configuration for balanced three-phase circuit protection.
  • Circuit Breaker Type: NB frame trip unit, designed as a trip unit only replacement component.
  • Compact Dimensions: 8.25 in width x 8.25 in height x 5.5 in depth footprint for straightforward integration.

Certifications & Compliance

  • UL 489 Listed

Technical Specifications

  • Circuit breaker type: NB
  • Department: Electrical

Typical Applications

  • Commercial and Industrial Power Distribution Systems
  • Switchgear and Panelboard Trip Unit Replacement
  • Three-Phase Motor Control and Feeder Protection
  • Heavy-Duty Industrial Load Protection
  • High Fault-Current Distribution Equipment

Why Eaton?

Eaton engineers the NB Series trip unit to deliver dependable, UL 489 listed overcurrent protection backed by a fixed thermal, fixed magnetic trip design rated for a 100 kAIC interrupt rating at 250 Vdc. For electrical professionals maintaining or retrofitting molded case circuit breakers, this trip unit offers the code-compliant reliability required for critical three-pole power distribution applications.

Manufacturer Resources

Product Specs

Product Width:
8.25 in
Magnetic Trip Range:
2000-4000A
Voltage Rating:
600V
Amperage Rating:
400A
Product Length/Depth:
5.5 in
Circuit Breaker Frame Type:
Trip unit
Product Height:
8.25 in
Product Type:
Circuit Breaker
Prod Load:
Pressure
Number Of Poles:
Three-pole
Line:
Pressure
Trip Rating:
2000-4000 A
Interrupt Rating:
100 kAIC at 250 Vdc
Circuit Breaker Type:
NB
Trip Type:
Fixed thermal, fixed magnetic
Certifications:
UL 489
Department:
Electrical
Series:
NB
Standards:
UL 489
Product Group:
Circuit Protection
Product Subgroup:
Circuit Breakers
Product Weight:
4 lb
Product Length:
5.5 in

Eaton NB3400PT – Frequently Asked Questions

1) Is the Eaton NB3400PT a complete circuit breaker or just the trip unit?
NB3400PT is a trip unit only, not a complete breaker. It installs into an existing Eaton NB frame molded case breaker as the interrupting and sensing element. If you need a full assembly, you also need the NB frame body it mounts into; ordering this part alone gets you the 400A three-pole trip unit and nothing else.
2) What voltage can the Eaton NB 400A trip unit be used at, AC and DC?
It carries a dual rating: 600 Vac and 250 Vdc. That covers three-phase 480Y/277 and 600 V commercial feeders as well as 250 V DC distribution, so the same part works on both sides of a plant with DC buses. The 100 kAIC interrupting figure on record is stated at 250 Vdc.
3) Will a 400A NB trip unit hold up on a high fault current service?
The NB3400PT is rated 100 kAIC at 250 Vdc, which is the interrupting figure on record for it. On a service with high available fault current, your engineer needs the available fault duty at the breaker location to fall within the rating at the system voltage you are applying it at. UL 489 listing covers it as a branch circuit and feeder overcurrent device.
4) Can the magnetic trip be adjusted on the Eaton NB3400PT, and what is the range?
The instantaneous magnetic setting ranges 2000 to 4000 A, so you can set the instantaneous pickup from 5x to 10x the 400 A rating for coordination with downstream devices or to ride through motor inrush. The thermal element is fixed at 400 A and is not adjustable, so long-time protection is set by the unit you order, not by a dial.
5) Is a fixed thermal-magnetic trip unit the right choice, or should I be looking at an electronic trip?
Fixed thermal-magnetic, as used on the NB3400PT, gives a predictable time-current curve without any electronics to age or lose settings, and it is the usual choice for feeder and branch protection where the load is well understood. Electronic trip units are what you want when you need adjustable long-time, short-time and ground fault bands for tight selective coordination in a multi-tier distribution system. If your coordination study only calls for an instantaneous adjustment, the 2000 to 4000 A magnetic range here covers it.
6) Can I use this three-pole NB trip unit on a single-phase circuit?
It is built as a three-pole device for balanced three-phase protection. You can land a two-wire single-phase load on two of the three poles, but you are buying and installing three poles worth of hardware and the third pole sits unused, so for a dedicated single-phase feeder a two-pole device is the cleaner specification.
7) What is the footprint of the Eaton NB 400A trip unit for panel layout?
It measures 8.25 in width by 8.25 in height by 5.5 in depth. Use those figures when you are checking gutter space and door clearance in switchgear or a panelboard before you schedule the outage.
8) What part number do I order for the Eaton 400A three-pole NB trip unit?
The manufacturer part number is NB3400PT, an Eaton NB Series 400 A three-pole trip unit rated 600 Vac / 250 Vdc. Quote that number when you are matching an existing NB frame breaker in switchgear or a panelboard.
How fast can I get the Eaton NB3400PT delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Eaton NB3400PT come with a warranty?
Absolutely. The Eaton NB3400PT is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Eaton NB3400PT?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
Why buy the Eaton NB3400PT from ZenSupply?
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