SurLok® Compression Lug | Reliable RADSOK® Power Connection

The RADSOK® SurLok® compression lug is a field-installable high-current power interconnect designed for protected indoor applications where engineers need a reliable, removable alternative to traditional bolt-on compression lugs. Built on Amphenol Industrial Operations’ proven RADSOK® high-current contact technology, SurLok® supports high ampacity, low contact resistance, and repeatable mating performance for power distribution systems inside cabinets, racks, and other enclosed equipment.

As the original SurLok® platform, this non-environmental compression lug is best suited for indoor equipment where environmental sealing is not required but serviceability and dependable power connections still matter. For new designs requiring a sealed, more compact, and more rugged high-voltage interconnect, engineers should consider SurLok Plus® as the preferred solution.

Table of Contents

• RADSOK® SurLok® Compression Lug Overview
• How the SurLok® System Works
• Typical Applications & Markets
• Installation, Tooling & Safety Considerations
• Choosing SurLok® vs. SurLok Plus®
• Engineer & Buyer FAQ

RADSOK® SurLok® Compression Lug Overview

The SurLok® compression lug creates a removable, plug-in power interface between a terminated cable and a busbar-mounted mating pin. Instead of relying on a permanently bolted compression lug, SurLok® helps simplify installation, maintenance, and module replacement by giving designers a serviceable high-current connection inside protected equipment.

Each lug is crimped to the cable using standard compression tooling, then pushed onto the mating pin until the locking feature engages. A two-piece plastic housing snaps over the mated interface to provide touch protection and a clear indication that the connection is fully seated. This makes the RADSOK® SurLok® compression lug especially useful in cabinet-based power distribution systems where quick service access and repeatable assembly are important.

SurLok® is intended for non-environmental applications located inside protected enclosures. Where environmental sealing, IP ratings, EMI shielding, or HVIL functionality are required, the SurLok Plus® family is the better fit.

How the SurLok® System Works

At the core of the RADSOK® SurLok® compression lug is Amphenol’s RADSOK® contact technology. Unlike a traditional solid cylindrical socket, RADSOK® uses a stamped and formed hyperbolic grid structure that increases contact surface area around the mating pin. This design supports high current carrying capability with low contact resistance while helping maintain manageable insertion forces.

A typical SurLok® installation includes three main elements:

• Cable-side SurLok® lug – A compression lug containing the RADSOK® socket, crimped onto the conductor using standard compression tooling.
• Bus-side pin or stud – A mating interface mounted to a busbar or laminated bus structure inside the equipment.
• Two-piece plastic housing – A snap-on housing that provides touch protection, strain relief, and visual confirmation of proper engagement.

Once terminated, the lug is pushed straight onto the bus-side pin until the locking feature engages. When service is needed, the connection can be removed without cutting the cable or disturbing a permanent bolted joint, which can help reduce maintenance time in modular systems.

Typical Applications & Markets

The RADSOK® SurLok® compression lug is best suited for high-current power distribution in indoor or otherwise protected environments where serviceability is important. Typical applications include:

• Industrial power distribution cabinets – Busbar systems, switchgear, and enclosed power assemblies.
• UPS and backup power systems – Battery drawers, modular power shelves, and replaceable high-current assemblies.
• Factory automation and process control equipment – High-current DC power connections within control panels and equipment racks.
• Protected heavy equipment or rail compartments – Interior power modules located away from direct environmental exposure.
• Test and measurement systems – Load banks and power test racks that benefit from removable high-current cable connections.
• Legacy energy storage and DC power shelves – Cabinet-based installations where a field-installable compression lug is preferred.

For outdoor, mobile, or harsh-environment platforms exposed to moisture, dust, vibration, or road spray, the sealed SurLok Plus® heavy-duty power connector family is generally the better choice.

Installation, Tooling & Safety Considerations

The RADSOK® SurLok® compression lug is designed for installation with common compression tools already used in many electrical assembly and field service environments. Typical installation steps include:

• Cable preparation – Strip the conductor according to the product documentation, taking care not to damage the strands.
• Crimp termination – Insert the conductor into the SurLok® barrel and crimp using the correct U-indent, clamshell, or 4-indenter die matched to the wire size and color code.
• Mating and locking – Align the lug with the mating pin and push until the locking feature engages.
• Housing installation – Snap the two-piece plastic housing over the mated connection and verify that all latches are fully seated.

Because SurLok® is intended to function as part of a complete electrical assembly, designers and installers should always follow applicable electrical codes, equipment safety requirements, and the latest Amphenol Industrial Operations product documentation when specifying or assembling these systems.

Choosing SurLok® vs. SurLok Plus®

SurLok® and SurLok Plus® both leverage RADSOK® technology and both support field-installable high-current power connections, but they are intended for different design environments.

• SurLok®
  • Type: Non-environmental compression lug with snap-on plastic housing.
  • Best for: Indoor, protected power distribution systems inside cabinets, racks, and enclosed equipment.
  • Key advantages: Standard crimp tooling, removable plug-in bus connection, and proven suitability for legacy and protected installations.
• SurLok Plus®
  • Type: Environmentally sealed heavy-duty power connector family.
  • Best for: Harsh-environment, mobile, outdoor, energy storage, and traction battery applications.
  • Key advantages: Sealed construction, compact packaging, touch-safe designs, and support for advanced features such as HVIL and EMI options depending on configuration.

For protected cabinet installations where environmental sealing is not required, SurLok® remains a practical and proven compression lug solution. For most new high-voltage designs exposed to harsher operating conditions, SurLok Plus® is generally the preferred platform.

For background on ingress protection classifications used in electrical equipment design, see the IEC overview of IP ratings.

Engineer & Buyer FAQ

• What is a RADSOK® SurLok® compression lug and where is it used?
  A RADSOK® SurLok® compression lug is a field-installable high-current power interconnect designed for protected indoor environments. It is commonly used in cabinets, UPS systems, control panels, equipment racks, and other enclosed power distribution applications that benefit from a removable, serviceable bus connection.
• How is a SurLok® lug terminated and what crimp tools are required?
  SurLok® lugs are terminated using industry-standard U-indent, clamshell, or 4-indenter compression tools with the appropriate dies matched to the conductor size and lug color code. No proprietary crimp tooling is required.
• Is the SurLok® connection touch-safe?
  Once fully mated, the two-piece plastic housing snaps over the connection to provide touch protection and visual confirmation of full engagement when properly installed according to product documentation and applicable safety practices.
• When should I choose SurLok® instead of SurLok Plus®?
  Choose SurLok® for protected indoor applications where environmental sealing is not required. Choose SurLok Plus® for sealed, mobile, outdoor, or harsher high-voltage environments that require a more rugged and compact interconnect platform.
• Can SurLok® still be used in new designs?
  Yes. SurLok® remains a good option for new cabinet-based and other protected installations that benefit from a field-installable compression lug. However, SurLok Plus® is generally preferred for most newer harsh-environment and high-voltage mobile platforms.
• Where can I find detailed ratings and part numbers for SurLok®?
  Detailed electrical, mechanical, and application information can be found in the latest SurLok® datasheets and product literature available on the Amphenol Industrial Operations website.