If you have an older Cutler-Hammer or Westinghouse busway system and need a replacement bus plug, the first question isn't amperage — it's which busway family you actually have.

CP2, CP4 and Pow-R-Way are not universally interchangeable. A bus plug that looks right or has the correct amperage may still be wrong for the busway. Here's what you need to know to identify your system and start looking for the correct replacement.

CP2 vs. CP4 vs. Pow-R-Way at a Glance

The most important takeaway: CP4 busway was designed to accept CP2 and CP3 bus plugs. Pow-R-Way is a different busway family, and its plugs are not interchangeable with vintage Cutler-Hammer CP2/CP3/CP4 plugs.

What Is CP2 SAFETYBUS?

CP2 SAFETYBUS was introduced by Cutler-Hammer in 1970. Its feeder busway used sandwich construction, while the plug-in version used separated busbars supported by corrugations in the housing. CP2 also used Mylar-wrapped busbar insulation and a single-bolt bridge joint design.

For someone maintaining an existing CP2 system today, the construction history is less important than correctly identifying the busway and replacement plug.

CP2/CP3/CP4 SAFETYBUS applications included both circuit breaker and fusible units. Eaton's aftermarket documentation lists breaker frames including EHD, FDB, FD, HFD, FDC, JDB/JD, KDB/KD, LDB/LD, MDL/HMDL and several TRI-PAC frames, depending on the required amperage and application.

What Changed with CP4 SAFETYBUS?

Cutler-Hammer introduced CP4 SAFETYBUS in 1985. CP4 moved the plug-in busway to a sandwich design and incorporated 130°C Mylar busbar insulation, a UL-recognized case ground path and the CP3 bridge joint package.

For replacement purposes, however, one CP4 feature matters more than all the others:

CP4 busway accepted CP2 and CP3 bus plugs.

That compatibility is important when you're trying to maintain an older SAFETYBUS installation or identify a plug already installed on a CP4 run.

CP4 Fusible Plug Voltage and Amperage Options

Eaton's aftermarket documentation lists CP4HD fusible switch plug-in units in the following configurations:

• 240V, 3-phase, 3-wire: 30A, 60A, 100A, 200A, 400A and 600A
• 120/208V, 3-phase, 4-wire: 30A, 60A, 100A, 200A, 400A and 600A
• 600V, 3-phase, 3-wire: 30A, 60A, 100A, 200A, 400A and 600A
• 277/480V, 3-phase, 4-wire: 30A, 60A, 100A, 200A, 400A and 600A

Other SAFETYBUS configurations, including certain bolt-on units and cable tap boxes, extend into the 800A range. That's one reason amperage alone isn't enough to identify the correct replacement.

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Where Does Pow-R-Way Fit In?

Westinghouse introduced Pow-R-Way in 1971. Although it dates from roughly the same era as CP2, it is a different busway family.

Pow-R-Way used sandwich construction in both feeder and plug-in busway, along with a bolt-end/slot-end design and single-bolt joint connection. Eaton's history lists Pow-R-Way busway ratings from 600A through 5000A.

But if you're sourcing a replacement plug, remember this:

Pow-R-Way plugs are not interchangeable with CP2, CP3 or CP4 SAFETYBUS plugs.

Eaton specifically warns that plugs for vintage Cutler-Hammer busway, Pow-R-Way busway and Pow-R-Way III busway are not interchangeable.

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Don't Identify a Bus Plug by Appearance Alone

Legacy bus plugs can look similar from the outside. That's not enough to determine whether a replacement will fit.

Before ordering a CP2, CP4, Pow-R-Way or other replacement bus plug, gather as much of the following information as possible:

• Manufacturer and busway series
• Catalog number, style number or shop order number
• Voltage
• Amperage
• 3-wire or 4-wire configuration
• Ground and neutral requirements
• Circuit breaker or fusible configuration
• Breaker frame and trip rating, if applicable

For bolt-on SAFETYBUS units, additional details may be required, including the type of busway, front or rear mounting, and load-left or load-right orientation.

Not Sure Whether You Have CP2, CP4 or Pow-R-Way?

You don't have to identify it from memory or guess based on the enclosure.

Take clear photos of:

• The busway nameplate
• The bus plug nameplate
• The complete bus plug
• The plug stabs or connection points, if safely accessible

Send the photos along with any available voltage, amperage, breaker or fuse information to EMSCO. Our team can help identify the busway system and check our inventory for a compatible replacement.

Don't see the exact CP2, CP4 or Pow-R-Way equipment you need online? Our online inventory is only part of what we have available.

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