Product Downloads


Get a free estimate


Or Call Us Today for a Quote:


Product Description and Specifications

Series: ZB30 – 30 Cycle
Applications: Critical Applications
Amperage: 1,000 – 3,000
Poles: 3 or 4
Voltage: 600V max

The Zenith ZB30 is a UL tested 30-cycle short time rated Bypass/Isolation Transfer Switch that is utilized with Over Current Protective Devices (OCPD) to facilitate selective coordination. The ZB30’s industry leading short time rating and best-in-class footprint greatly simplifies the selective coordination design process and provides the utmost in system design flexibility for future system growth. The ZB30 supplies 100% rated power to loads after an overcurrent event, helping to maximizing power distribution system reliability and uptime. The ZB30 is available in standard, delayed and closed transition modes.

The ZB30 Series Bypass-Isolation Transfer Switches are the solution when interruption of power during service or testing is not acceptable. Consisting of two major modules-the Automatic Transfer (ATS) and the Bypass/Isolation Switch – the ZB30 Series incorporates the rugged construction of all our ZT30 Series automatic switches with a quick make/quick break bypass switch manual load transfer handle (for standard and delayed transition only) and our control/interlock system, which consists of both mechanical and electrical interlocks.

The bypass uses normal failure sensing and a time delay to start the engine automatically if a failure occurs when the ATS has been removed for service, which can be done without disturbing the load.


ZB3ST – Standard (Open) Transition
The Zenith ZB3ST Bypass/Isolation transfer switch is used in general and mixed load applications.

ZB3DT – Delayed Transition
The Zenith ZB3DT Bypass/Isolation transfer switch has an adjustable time delay in the centered “off” position. This delay allows motor loads to coast down and transformer field to decay; ensuring inductive loads are re-energized after transfer with only normal inrush starting currents.

ZB3CT – Closed Transition
The Zenith ZB3CT Bypass/Isolation transfer switch is used in critical/life safety applications where a “no break” transfer is desired during periodic testing and maintenance.

Features & Benefits

  • Reliability / Performance
    • Facilitates selective coordination design
    • Maximizes system uptime & reliability
    • Industry-leading short time rating (withstand & close-on)
  • Safety
    • Manual Quick Make/Quick Break operation (Standard and Delayed Transition)
    • Manual operation with the door close
    • “Shutter System” – for bypass switches adds another of layer of protection during maintenance
  • Ease of Installation/Maintenance
    • 100% top or bottom cable entry
    • Interchangeable source cable terminations
    • Mechanical switch position indicator
    • Master terminal connection for customer control wiring
    • Cable bracing not required
  • Space Optimization/Flexibility
    • Best-in-class footprint
    • 3-pole & 4-pole in the same footprint
    • Field upgradeable from 3-pole to 4-pole
    • Simple field configurable voltage selection


  • 30 Cycle Short Time – UL1008 Listed, Tested and Labeled
  • Transition Type: Standard, Delayed, Closed
  • Amperage Rating: 1000A to 3000A
  • Poles: 3 or 4 pole switching
  • Voltage: 600VAC max
  • Short Time Rating:
    • 85kA: 30 Cycle (0.5s)
    • 100kA: 3 cycle
  • Withstand and Close-on Rating:
    • 100kA: 3 Cycle
    • 200kA: with Current Limiting Fuse Class L
  • Transfer Time:
    • Standard (Open) Transition: ~ 30ms to 70ms
    • Delayed Transition: ~80ms (Customer Programmable Time Delay Setting)
    • Closed Transition: Less than 100ms parallel
  • Enclosure Types: Open Style, NEMA 1, NEMA 3R, NEMA 4, NEMA 4X, NEMA 12
  • Microprocessor Controller: MX250, MX350
  • Certifications: UL/cUL rated up to 600V at 50/60Hz, Seismic Qualified to IBC-2009 & IEEE 693-2005, OSHPD
  • Code Compliance: NFPA 70, 99, 101, 110; IEEE 446, 241, 602: NEMA ICS 10, CC1 (lug)
  • Enclosure Compliance: UL 50, UL 508, NEMA 250

Questions? Call us toll free at 1-800-370-3621 or send us a message now. We’re here to help.