Browse Store Westinghouse TAP, ITAP and ZTAP bus plugs can look very similar, but they are designed for different busway systems and are not interchangeable.
If you're trying to replace an existing Westinghouse or legacy Cutler-Hammer bus plug, don't identify it by enclosure shape alone. The part-number prefix, stab arrangement and hanger width can help determine which series you have.
TAP vs. ITAP vs. ZTAP: Quick Identification
| Series | Busway | Busway Rating | Stab Configuration | Key Identification Clue |
|---|---|---|---|---|
| TAP | Westinghouse Standard-Design | 225A–1000A | Aligned | TAP prefix; 9-5/8 in. hanger width |
| ITAP | Westinghouse Pow-R-Way I & II | 225A–4000A | Staggered / offset | ITAP prefix and offset stabs |
| ZTAP | Westinghouse Low-Impedance | 1000A–4000A | Aligned | 11-5/8 in. hanger width; may use TAP prefix |
The biggest trap is TAP vs. ZTAP. Both can have aligned stabs, and a ZTAP plug may even have a part number beginning with TAP. That's why the label alone isn't always enough.
How to Identify a TAP Bus Plug
TAP bus plugs are used with Westinghouse Standard-Design busway rated from 225A through 1000A. They were available in both 3-wire and 4-wire configurations.
The easiest clues to check are:
- Stabs: The phase stabs are aligned in a row.
- Neutral: On a 4-wire TAP plug, the neutral is offset from the phase stabs.
- Part number: The product label typically begins with the prefix TAP.
- Hanger width: TAP hanger brackets measure approximately 9-5/8 inches wide.
That last measurement becomes especially important when distinguishing a TAP plug from a ZTAP plug.
How to Identify an ITAP Bus Plug
ITAP bus plugs are used with Westinghouse Pow-R-Way I and Pow-R-Way II busway rated from 225A through 4000A. They were also available in 3-wire and 4-wire configurations.
ITAP is usually the easiest of the three families to identify:
- Stabs: ITAP stabs have a distinctive staggered or offset arrangement.
- Part number: The product label should use an ITAP prefix.
If the stabs are aligned rather than staggered, you're likely looking at a different Westinghouse bus plug family.
How to Identify a ZTAP Bus Plug
ZTAP bus plugs are used with Westinghouse Low-Impedance busway rated from 1000A through 4000A. ZTAP plugs can be more difficult to identify because of their similarity to TAP plugs.
Look for these clues:
- Stabs: The phase stabs are aligned.
- Neutral: On a 4-wire ZTAP plug, the neutral stab is also aligned with the other stabs.
- Hanger width: ZTAP hanger brackets measure approximately 11-5/8 inches wide.
- Part number: Don't rely on the prefix alone. ZTAP plugs may also have part numbers beginning with TAP.
The wider hanger brackets are one of the best physical clues. Compared with the 9-5/8-inch TAP hanger, the ZTAP hanger measures approximately 11-5/8 inches and extends farther beyond the enclosure.
TAP or ZTAP? Check These Two Details
If you're stuck between TAP and ZTAP, focus on hanger width and the neutral stab position.
| Identification Detail | TAP | ZTAP |
|---|---|---|
| Hanger Width | Approx. 9-5/8 in. | Approx. 11-5/8 in. |
| Phase Stabs | Aligned | Aligned |
| 4-Wire Neutral Position | Offset | Aligned |
| Label Prefix | TAP | May also begin with TAP |
Do not order a replacement based only on seeing "TAP" on the label. Check the physical configuration as well.
What to Send EMSCO for a Replacement Bus Plug
If you're still not sure which Westinghouse bus plug you have, don't guess. Send us enough information to verify the series before ordering.
For the fastest match, send:
- A clear photo of the bus plug nameplate
- A photo showing the stab configuration
- A photo of the busway nameplate, if available
- The hanger width if you're trying to distinguish TAP from ZTAP
- Amperage and voltage
- 3-wire or 4-wire configuration
- Ground requirements
- Breaker or fusible configuration
EMSCO stocks used, surplus, obsolete and professionally reconditioned bus plugs, including legacy Westinghouse and Cutler-Hammer equipment. Not everything in our inventory is listed online, so contact us if you don't see the exact plug you need.
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