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Comparing TAP and ITAP Bus Plugs
Overview
An issue we see at Legacy is trouble identifying the correct bus plug for older Westinghouse / Cutler Hammer busway. The confusion stems from the similarity in bus plug names and the appearance. However the bus plugs are not interchangeable, and it is important to correctly identify which bus plug is required.
The Issue
TAP and ITAP bus plugs were both introduced by Westinghouse and share similar physical characteristics in terms of the enclosure dimensions, handle placement, and operation. The most notable difference between the two bus plug series is the stab configuration; the prongs that connect the bus plug to the busway.
While the bus plugs may appear to be the same they are not interchangeable. The TAP bus plugs are for the Lifeline/Standard busway system. The ITAPs are designed for use with the Pow-R Way bus duct system.
Adding to the problem is that Westinghouse (and Cutler Hammer and Eaton) used a “Style Number” and sometimes omitted the more standard (and clearer) “Catalog Number” on the bus plug tag.
A few examples of different labels on the TAP364 bus plug.
The confusion is compounded by the similarity of the catalog numbers, “TAP” versus “ITAP”. The one small letter at the front of that catalog number makes a large difference. Someone who is less familiar, or is under pressure to get the job done quickly can easily miss the difference.
We continually work with these bus systems and bus plugs and we still have to double check.
The catalog number identifies a bus plug for a particular manufacturer. In the above label image, the bus plug catalog number is a “TAP364”. This identifies the bus plug as a TAP series plug, 3 wire (no neutral), 600 volt, 200 amp.
Background
Westinghouse began offering the Standard busway series in 1947 and the Lifeline series in 1955. These two series, while using different names are the same series of busway. Both of these series, Lifeline and Standard, use the TAP style bus plug to access electrical power through plug-in ports on the busway.
In 1971 Westinghouse introduced the Pow-R Way® busway series. The Pow-R Way® series is a sandwich style bus duct that accepts the ITAP bus plugs. In the following years, the Westinghouse busway was acquired by Cutler-Hammer and Eaton Corporation. The busway series’ are currently “owned” by Eaton.
To confuse things more Eaton’s current line is the Pow-R Way® III series, which takes the P3F bus plugs. The earlier model TAP and ITAP series bus plugs are not interchangeable with the newer P3F bus plugs.
Identifying TAP and the ITAP Bus Plugs
The easiest way to distinguish between the two series of bus plugs is to check the catalog number on the bus plug’s tag. However, if there is no catalog number, or no tag, then the bus plugs can be identified from their physical characteristics.
Bus Plug is Not Installed
One way to discern a TAP bus plug from an ITAP bus plug is the stab configuration.
- TAP – the TAP bus plug’s stabs are in a row.
- ITAP – the ITAP bus plug’s stabs are staggered.
In the above image with the two rear-facing bus plugs, the TAP bus plug is on the left, and the ITAP bus plug is on the right
Both bus plugs, the TAP on the left and the ITAP on the right, are shown with a neutral installed. Denoted by a “N” at the end of the catalog number, i.e. a TAP 600 volt, 30 amp catalog number would be a TAP361N.
The images of the stab configuration of these plugs can be compared to the stab configuration of the bus plugs in the image at the beginning of this section, which are 3 wire (or no neutral).
This method of telling the two bus plugs apart only works if there is a bus plug unit that is not installed on the bus duct system.
Bus Plug is Installed
What if you are on the ground looking at bus that is hanging 25 feet in the air? Can you tell what type of bus plug needed?
One way is by identifying the busway series, Lifeline/Standard or Pow-R Way® I or II. The Lifeline/Standard busway is roughly 12” in height on its side with the ports for the bus plugs.
Pow-R Way busway is six inches on the side with the bus plugs, casing-to-casing.
The Lifeline/Standard busway is about twice the height of the Pow-R Way®.
Another possible indicator is if the bus plug hangers can be seen. Normally, the TAP bus plug hangers can be seen from the ground because they are more substantial to accommodate the wider Standard/Lifeline busway. This is not the case with the smaller Pow-R Way®, where the bus plug hangers are often hidden behind the bus plug when viewed from below.
Wrap Up
It is better to take the time to correctly identify the type of bus plug needed, TAP or ITAP or neither, than to order the wrong style of bus plug resulting in lost time, lost money, and frustration.
If you need assistance identifying a Westinghouse, Cutler Hammer, or Eaton bus plug, contact us by phone at 248-619-9710, email at [email protected] or through our website at www.legacyindustrial.com .
Legacy Industrial Electric LLC specializes in reconditioned busway systems. We can be reached at 248-619-9710, or by email at [email protected].
