How to Read Burndy YA, KA, and K2A Part Numbers

You're staring at a Burndy part number on a spec sheet or an old lug that needs replacing, and the alphanumeric string looks like gibberish. Whether you're cross-referencing for a retrofit, ordering replacements for a service call, or just trying to confirm you grabbed the right box from the truck, decoding Burndy's YA, KA, and K2A mechanical lug part numbers doesn't have to be a guessing game. These compression connectors follow a logical naming system once you know what each segment means.

Quick Answer

Burndy YA, KA, and K2A part numbers encode the lug family, conductor size range, number of holes, bolt size, and tongue length in a standardized format. The first letters identify the series (YA for standard aluminum, KA for aluminum compression, K2A for dual-rated), followed by numeric codes for wire range and mechanical dimensions. Understanding this Burndy YA KA part number guide lets you decode specifications instantly without hunting through catalogs.

Understanding Burndy Lug Family Designations

The prefix letters in a Burndy part number identify the product family and material compatibility. The three most common mechanical lug families electricians encounter are:

• YA Series: Standard compression lugs for aluminum conductors, designed per UL 486A-486B standards. These are your workhorse lugs for aluminum-to-copper transitions in panels, switchgear, and busbar connections.
• KA Series: Heavy-duty compression lugs for aluminum conductors with broader barrel designs to accommodate larger conductor ranges. Often specified in utility and substation applications.
• K2A Series: Dual-rated compression lugs listed for both copper and aluminum conductors under UL 486A-486B. The "2" designation indicates the dual rating, eliminating the need to stock separate copper and aluminum-specific lugs.

These families meet NEC Article 110.14 requirements for terminations when properly installed with the correct dies and compression tools. The material designation directly affects ampacity calculations per NEC Table 310.16 (now 310.15(B)(16) in current code), since aluminum conductors carry different current ratings than copper at equivalent sizes.

Decoding Wire Size and Hole Configuration

After the family prefix, Burndy part numbers contain numeric codes that specify conductor range and physical dimensions. Here's how to read the core specification segment:

For example, a YA4-12-2 breaks down as: YA (aluminum compression lug), 4 (4 AWG conductor), 1 (one hole), 2 (1/2" bolt hole), with the final digit indicating tongue length. A KA350-233 would be: KA (heavy-duty aluminum), 350 (350 kcmil conductor range), 2 (two holes), 3 (3/4" bolt), 3 (3" tongue length).

When you're working with unfamiliar part numbers or need to cross-reference to other manufacturers like Ilsco or Penn-Union, our mechanical lug cross-reference guide can save you time matching specifications across brands.

Conductor Range Specifications and Compression Tooling

Burndy lugs are engineered for specific conductor size ranges, and using the correct die set is critical for code compliance and connection integrity. The numeric conductor code tells you the maximum size, but most lugs accommodate a range:

Per UL 486A, compression connectors must be installed with the manufacturer-specified die and crimping tool. Using an incorrect die or under-crimping creates a high-resistance connection that fails NEC 110.3(B) requirements for listed equipment installation instructions. The die code is typically stamped on the lug barrel and must match your hydraulic or manual compression tool's die set.

K2A dual-rated lugs require particular attention to die selection since the same lug body accommodates both copper and aluminum. The compression force needed differs slightly between materials due to work-hardening characteristics, but the specified die works for both when properly applied.

Bolt Hole and Tongue Specifications

The mechanical dimensions in a Burndy part number directly affect how the lug interfaces with bus bars, breaker lugs, and transformer terminals. Getting these specs right prevents field modifications and ensures proper torque application per manufacturer specifications.

Bolt hole sizing follows standard fractional dimensions:

• Code "2": 1/2" diameter hole, accepts 3/8" and 1/2" hardware, common on 100-400A equipment
• Code "3": 3/4" diameter hole, accepts 1/2" and 5/8" bolts, typical for 400-800A applications
• Code "4": 1" diameter hole, accepts 3/4" and larger hardware, used in 800A+ and utility-grade equipment

Tongue length affects reach and clearance in tight panels. Standard lengths run 2", 3", and 4" measured from the barrel end to the bolt hole center. Longer tongues provide additional reach for recessed bus connections but require more clearance space. When space is critical in packed panels or switchgear, verify tongue length against available depth before ordering.

Two-hole configurations (indicated by "2" in the hole position) provide additional mechanical security and are often required by equipment manufacturers for larger conductors. The spacing between holes is standardized within each lug family but varies between YA, KA, and K2A series.

Material Ratings and Temperature Specifications

Beyond the part number geometry, understanding the material ratings encoded in the series designation is critical for code-compliant installations. All three lug families meet UL 486A-486B standards, but with different temperature and material ratings:

YA Series lugs are rated for 90°C aluminum conductors and tin-plated for corrosion resistance. The tin plating provides the low-resistance aluminum-to-copper transition required by NEC 110.14 when terminating aluminum conductors to copper bus bars or equipment.

KA Series lugs feature heavier barrel walls and broader conductor ranges, making them suitable for parallel conductor applications common in services above 400A. They maintain the same 90°C rating but with mechanical designs optimized for utility-grade installations.

K2A Series lugs carry dual copper/aluminum ratings at 90°C, certified under both UL 486A (aluminum) and UL 486A-486B (copper). This dual listing means a single SKU covers both conductor types, reducing inventory complexity. However, you must still verify conductor material compatibility with connected equipment per NEC 110.14(A).

For help identifying equivalent parts across manufacturers or confirming specifications for a specific application, our team can assist with cross-referencing mechanical lugs from various brands.

Common Part Number Examples Decoded

Let's walk through real-world examples to solidify the decoding process:

YA6-12-2:

• YA = Standard aluminum compression lug
• 6 = #6 AWG conductor (typically accommodates #10-#6 range)
• 1 = One bolt hole
• 2 = 1/2" bolt hole diameter
• 2 = 2" tongue length

KA350-233:

• KA = Heavy-duty aluminum compression lug
• 350 = 350 kcmil maximum conductor (range typically 250-350 kcmil)
• 2 = Two bolt holes
• 3 = 3/4" bolt hole diameter
• 3 = 3" tongue length

K2A4/0-14-3:

• K2A = Dual-rated copper/aluminum compression lug
• 4/0 = 4/0 AWG maximum conductor (range typically 1/0-4/0)
• 1 = One bolt hole
• 4 = 1" bolt hole diameter
• 3 = 3" tongue length

When ordering replacements or quoting projects, having the complete part number eliminates guesswork. If you're working from a partial number or need to match an obsolete SKU, you can request a quote with whatever information you have, and we'll help identify the correct current equivalent.

Frequently Asked Questions

What's the difference between Burndy YA and KA series lugs?

YA series are standard compression lugs for aluminum conductors with typical barrel dimensions. KA series are heavy-duty versions with thicker barrel walls and broader conductor ranges, commonly specified in utility and substation applications where mechanical strength and larger wire ranges are priorities. Both meet UL 486A-486B standards and are rated for 90°C aluminum conductors.

Can I use K2A dual-rated lugs for copper conductors?

Yes, K2A series lugs are UL-listed for both copper and aluminum conductors at 90°C. You must use the specified compression die for proper installation, and the same die works for both conductor materials. Always verify that your connected equipment is also rated for the conductor material you're using per NEC 110.14(A).

How do I know which compression die to use?

The required die code is stamped on the lug barrel and specified in Burndy's installation instructions. Using the correct die is mandatory for UL listing compliance and code approval per NEC 110.3(B). Common dies include W-series for smaller AWG sizes and U-series for kcmil ranges. Never substitute dies between manufacturers or lug families.

Are Burndy lugs interchangeable with other brands like Ilsco or Penn-Union?

While many mechanical lugs share similar dimensions, direct interchangeability isn't guaranteed due to variations in barrel design, compression ratios, and die specifications. Always verify conductor range, bolt hole dimensions, and tongue length match your application. Our cross-reference guide helps identify equivalent parts across manufacturers when exact replacements aren't available.

What does the tongue length measurement include?

Tongue length is measured from the end of the compression barrel to the center of the bolt hole(s). This dimension determines reach into equipment terminals and required clearance space. Standard lengths are 2", 3", and 4", with longer tongues providing more reach but requiring additional panel depth clearance.

Get a Quote on Burndy Mechanical Lugs

Whether you're outfitting a new installation, stocking service truck inventory, or sourcing replacements for a retrofit, Conversions Tech supplies Burndy YA, KA, and K2A mechanical lugs with technical support to ensure you get the right part the first time. Our team can help decode existing part numbers, cross-reference to available alternatives, and provide volume pricing for contractor and industrial accounts. Request a quote today with your specifications or part numbers, and we'll respond with availability and pricing within one business day.