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Grounds & Jumpers

As a service to its customers, Irby builds grounding and jumper sets based on customer specifications. Our knowledgeable sales team assists you through the ordering process to customize grounds and jumpers specific to your needs. We stock a wide range of clamps, cables and components that enable us to provide quick order turnaround, and we offer testing and repair on any used sets. Best of all, it is all offered at a competitive price.


Our grounds and jumpers sets are customized to your specifications. Cable is cut to order, clamps and ferrules are selected to meet your specific requirements and sets are tested to verify their resistance is within ASTM guidelines.

Once the set is complete, it is identified with an Irby serial number and date of assembly which are recorded on ship tickets and invoices. A serial number is established to identify individual parts, making the replacement or reorder process simple and fast. Irby works with you throughout the entire process to satisfy your requirements and exceed your expectations.


Not only does Irby offer quality assembled grounds and jumpers, but it also offers rapid turn around time on orders for common grounding sets. In most emergency situations, Irby can build and ship grounds and jumpers on the same day the order is placed.

"I contacted Irby on a Tuesday afternoon regarding a need for jumpers. I received the custom jumpers from Irby on Friday morning. I am very pleased with the quick response."

- Rodney Weaver, General Line Foreman, City of Ocala, Florida


Irby is your supplier of choice when it comes to testing and repairs for grounds and jumpers. Irby can test all sets - whether they were assembled by Irby or not - to certify they remain usable and in compliance with safety regulations. Irby inspects, cleans and tests grounds and jumper sets in accordance with ASTM F2249-03 and ASTM F2321-05. Our repair shop can also clean grounding sets, beadblast clamps and ferrules, or replace any necessary parts to keep your sets functioning properly.

Grounding Equipment

A grounding set consists of 3 main parts: two clamps, a length of cable and a pair of ferrules. Clamps can be identical to each other or different from one another depending on the application of the grounding set. Different clamp styles are available to meet the functional needs of the grounding set. The cable is the second component; the size depends on the short circuit current capacity of the system being grounded. Lastly, ferrules are required to attach a clamp to the grounding cable. Ferrules are compressed on the strands of the cable to provide a permanent, low resistance connection. The size of the ferrules is determined by the size of the cable while the type of ferrule is determined by the clamp style. All grounding clamps, ferrules and cable meet ASTM F855 standards.

Criteria to consider when selecting your components:

  • Functionality - The function of your grounding set determines clamp style.
  • Adequate Capacity - The maximum-potential system fault-current magnitude and full-time duration determines clamps and cable.
  • Coordinated Connectors - The terminal of the clamp style - pressure or threaded - determines the ferrule style - plain or threaded.
  • On-Site Handling - The application of the grounding set affects the clamp and cable dimensions.


Apparatus Grounding Clamps

Although apparatus clamps have a compact design, they deliver a high current rating for applications in areas with restricted space or as a truck-grounding system. Clamps apply to a wide range of switching equipment including industrial metalclad gear, outside and inside substations and overhead and underground distribution.

Cut-out Grounding Clamps

These clamps are used to ground the bottom hinge contact on cutouts used on distribution riser poles or where grounding is required. Clamps can be installed with or without grounding cable to aid as a warning and possibly avoid accidental closing of cutout. The drilled terminal of these clamps accepts threaded-stud cable ferrules and threaded L-stud and T-stud terminals when used with conventional grounding sets.

Penetrator Grounding Clamps

Penetrator clamps are special C-Type clamps that help ensure contact with a center conductor for temporary grounding of underground distribution cable with jacket over concentric neutral.


Copper Grounding Cable

Copper grounding cable is extra flexible for handling ease yet strong and tough enough for longwear. At Irby, grounding cable is available in two different jacket colors - yellow and clear. The cable jacket is smooth with resistance to abrasion, weather and oil in accordance to ASTM specifications. The cable is embossed with AWG size every 4 feet to ensure reading ease.

The yellow jacket is a T-prene rubber compound and has a recommended low temperature of -20º Fahrenheit. Clear ultraviolet PVC-jacketed cable allows easy inspection of strand condition and has a recommended low temperature of 0º Fahrenheit. NOTE: Because of the extra-fine strands in extra flexible cable, termination ferrules - either aluminum or copper - are required when using such cable and ground clamps.


Ferrules are shafts designed to reinforce or to prevent splitting of the connection between the grounding clamp and the grounding cable. There are three different criteria to consider when choosing copper ferrules for the grounding: copper or tin-plated copper; shrouded or unshrouded; and plain or threaded. Shrouded ferrules overlap the jacket of the grounding cable for stress relief to the terminal. Two crimps secure the ferrule against the bare strands and one crimp applies on the jacket. Unshrouded ferrules are available with shrink tubing that overlaps the bare cable conductor and jacket for stress relief. It is the customer's preference that determines whether a ferrule is shrouded or unshrouded. The type of ferrule - plain or threaded - is determined by the chosen clamp.

Shrink Tubing

A translucent shrink tubing and seal is recommended for stress relief and inspection of cable strands between ferrule and jacket. When used with a seal, the shrink tube helps prevent moisture ingress.

Support Studs

Support Studs can be installed on any grounding clamp in place of the restraining strap immediately below the terminal. It serves as a mechanical parking stand for a second clamp - preventing the clamp from making contact with the conductor or ground. Such a feature is beneficial in the three phase grounding application.


Ball Stud and Cover

Ball Studs are used on equipment grounds, substations, and switchgear. Nonconductive ground stud covers may help prevent flashover on ball studs installed in enclosed switchgear, switchyards or substations. Ball stud covers are intended for environmental protection from corrosion and contamination; they are not for personal protection and should not be considered as insulated cover-up equipment.


L-stud Terminal

L-stud Terminals are to be used with Cutout Grounding Clamps when Cutout Clamps are used with a conventional grounding set. The L-stud is made of bronze metal and is 3/4" in diameter.


Block Terminal

Block Terminals are used to attach ground leads from grounding clamps to a common ground. Terminals accommodate 4/0 AWG size grounding cables.


Cluster Bars

Cluster bars are to be used for wood, steel and concrete poles for phase-to-phase grounding technique. The bar consists of a compact, 5" aluminum-alloy bar with a 5/8" diameter that accepts C-type or Duckbill clamps, an adjustable wheel binder and a 36" chain.




Grounded Parking Bushing Sets include a loadbreak bushing and bronze ground clamp connected by a 4-ft. yellow 1/0 cable. A tin-plated copper connector joins the cable to the bushing and a threaded copper ferrule connects the cable to the clamp.

Grounding Elbow Sets for Single and Three-Phase Switches & Transformers include yellow-jacketed grounding elbows, 6 feet of 1/0 cooper grounding cable with yellow jacket and a bronze ground clamp. For three-phase sets, a three-way terminal block is used.

Temporary Grounding Sets for Live-Front Switches & Transformers are available with C-Clamps, Flat-Faced Clamps, or Ball-Stud Clamps.

  • C-Clamp and Ball-Stud Sets include a three-way terminal block, four bronze ground clamps and three 6-ft., 2/0 copper clear-jacket ground cables with threaded-stud ferrules.
  • Flat-Faced Clamp Sets include a four-way bronze terminal block, one 6-ft. and three 4-ft., 1/0 copper clear jacket ground cables with shrouded plain-plug copper ferrules, three bronze ground clamps with eyescrews and one bronze T-handle clamp.


Spiral Temporary Grounding Rods

Grounding rods provide a temporary ground where a system ground is not available. When installed, the 6' spiral grounding rod develops less resistance than straight grounding rods. Although there is less resistance, actual effectiveness depends upon soil properties. Material: ground rod is copper clad; spiral and handle are bronze.


Portable Storage Cable Reels

Hubbell Powers Systems portable reel quickly pays-out and takes up and helps keep ground sets clean, neat, and ready for use. Lightweight units can either be carried to the site or bolted to a deck or truck. Reel is for storage only; therefore, clamps and cables need to be completely removed to avoid dangerous voltage drop and violent mechanical reactions. Reel capacity is determined by grounding cable size.


Insulated Jumper Clamps

Mechanical Jumpers are used for bypassing work areas where equipment is under repair or when the line is being upgraded. The orange handles are manufactured from high impact strength polyethylene and have a hand guard flange. Clamps clear in color are manufactured from high impact polycarbonate material with ultra violet inhibitors to hinder discoloration. Clamps are duckbill in type allowing jumpers to be supported by the conductor while hand tightened. Clamps contain bronze serrated rings to ensure proper electrical contact, and they have molded grip tabs for easy gripping with rubber gloves. Although clamps are insulated, adequate rubber gloves must be worn when installing or removing jumper clamps.



Jumper Cable

Jumper cable features an insulation and jacket combination to ensure resistance against abrasion, heat, oil, moisture and ozone. The coating is mold-cured ethylene-propylene based to ensure extreme flexibility even in low temperatures. The orange color creates high visibility, and the embossed conductor size and kV rating is found every 4 feet, which allows for easy identification. All Cable is Type I per ASTM F2321 standard specification.

All jumper cables are fine stranded copper and alloy coated for extra flexibility in adverse conditions. The conductor has a strand screen between it and the insulation to relieve voltage stress and improve dielectric strength and service life. Insulation and conductor screen meet and exceed ICEA-NEMA standard S-68-516.


Personal Protective Equipment

Hubbell Power Systems offers the EQUI-MATTM Personal Protective Ground Grid (Grid) to provide an easy way to establish an "equipotential zone" safe enough for a lineworker to stand during various energized work practices. The Grid is simple to use, maintain and store. It can be taken anywhere. It consists of a high-ampacity, tinned-copper-braid cable sewn in a grid pattern onto a vinyl/polyester fabric. It provides protection by permitting cable terminals to connect to the mat's grid in a series with an electrical ground and the subject. Multiple Grids can be connected together for larger areas.

When properly applied, the Grid is in compliance with OSHA 1910.269. Complete instructions for use are included with each unit.

Versatile applications include:

  • Mechanical Equipment Grounding
  • Padmounted Transformers and Switches
  • Overhead Distribution and Transmission Switches
  • Line Apparatus Work
  • Suspect Substation Grids

Jumper Assembly

Jumper Sets consist of three basic components: a pair of clamps, a length of insulated cable and a pair of ferrules. Based on preference and specifications, components shown on the following pages can be selected for custom jumper sets. All insulated jumper components meet ASTM F2321 standards.


Jumper Ferrules

Copper connectors are necessary to join clamp and cable together on jumper clamps. For Hubbell Power Systems Connector Assemblies, each ferrule consists of a copper connector, nut and lock-washer; all connectors have threads that are 5/8 - 11 UNC. Catalog numbers below can be used for 15kV, 25kV & 35kV jumper cable and are Type VI per ASTM F2321 standard specification.



These sets are to be used where installation with hot sticks is required. Sets can be assembled per your requirements. Shown here is JS20x12ccb: 2/0 x 12' 15kV MAC with C600-2271 bronze c-clam


Connector Link

This Salisbury item connects two insulated jumpers to create a longer jumper length. After the two clamps are connected to the link, the assembly can be wrapped with a small rubber insulated blanket.

Jumper Load Pick-Up Tool

The Hastings Load Pick Up Tool (with stud) can be installed with a shotgun stick or with rubber gloves. The tool comes completely self contained with cocking tool, firing lanyard and safety latch. The head casting is aluminum alloy while the housing is clear plastic. The translucent material allows for quick and easy visual inspection. Listed below are maximum ratings. Actual ratings depend upon the components of the jumper set.