Grounding & Bonding

How to Choose Grounding and Bonding Hardware for Electrical Installations

Grounding and bonding hardware forms the electrical connections that link grounding electrodes, conductors, metal raceways, and equipment. Choosing the correct part requires more than matching wire gauge. A clamp for a ground rod, a mechanical lug on an equipment terminal, and a bonding jumper across a moving connection serve different purposes. Begin with the actual connection point and the electrical design. Then compare conductor compatibility, permitted mounting surfaces, environmental conditions, and the manufacturer's listing or identification before ordering.

Quick Grounding and Bonding Hardware Selection Guide

• Ground rod or metallic pipe connection: Compare ground clamps identified for the specific electrode or pipe.
• Equipment terminal or grounding connection pad: Select a suitable mechanical lug with the correct conductor and mounting range.
• Connection subject to vibration or movement: Check a flexible bonding jumper approved for the application.
• Metallic raceway entering an enclosure: Determine whether an approved grounding or bonding bushing is required.
• Grounding conductor splice: Use a connector specifically identified for the conductors and grounding application.

Grounding vs. Bonding: Why the Electrical Connection Matters

Grounding establishes the connection between an electrical system and earth or its required grounding reference. Bonding electrically connects conductive parts to establish continuity and help maintain an effective fault-current path.

Consider a metal electrical enclosure. If an energized conductor contacts the enclosure, the equipment grounding and bonding system must provide an effective conductive path back toward the source so the protective device can operate.

A ground rod alone is not a substitute for that equipment fault-current path. The grounding electrode system and equipment grounding connections have distinct roles.

For a more detailed explanation of these functions, read Lumera's grounding and bonding guide.

Ground Clamps for Ground Rods, Pipes, and Other Approved Connections

Ground clamps connect a grounding or bonding conductor to an electrode or another identified conductive surface. Different clamp designs are intended for ground rods, metallic pipes, compatible conduit, or reinforcing steel.

For example, a 5/8-inch ground rod requires a clamp identified for that rod diameter. The clamp must also accept the specified conductor size and material.

Lumera carries Dottie ground rod clamps for several rod diameters, along with pipe-style, lay-in, feed-through, and direct-burial clamp configurations.

A clamp that fits around a water pipe is not automatically suitable for every pipe material or grounding-electrode application. The connection must be permitted by the electrical design and the product's identification.

Selection rule: Match both sides of the connection: the electrode or pipe dimensions and the conductor's size, material, and permitted quantity.

Mechanical Grounding Lugs: Match Conductor Size and Terminal Design

Mechanical lugs terminate conductors at compatible equipment terminals, connection pads, and other approved mounting points. Their specifications include the conductor range, acceptable conductor material, number of conductors, mounting-hole configuration, and termination method.

For example, Lumera lists the Morris 91316B turn-prevent lug, which accepts 6 AWG through 350 kcmil copper or aluminum conductors and uses a one-hole mounting arrangement.

Its turn-prevent feature helps keep the lug from rotating at the mounting point. However, a lug's conductor range and mechanical design do not independently establish approval for every grounding application.

Selection rule: Confirm the connector is identified for the intended grounding or bonding connection, not merely that it accepts the wire gauge.

Flexible Braided Bonding Jumpers for Movement and Vibration

Flexible bonding jumpers maintain electrical continuity between compatible conductive parts where movement, vibration, or expansion may make a rigid connection unsuitable.

These jumpers typically use a flexible conductive braid with terminal pads or other specified connection ends.

For example, the Morris 91620 flexible braided jumper strap is a 12-inch tinned-copper braid assembly with mounting pads.

Before selecting a flexible jumper, confirm the required conductor cross-section or current-carrying capability, connection length, mounting-hole arrangement, and environmental suitability.

A general-purpose braided strap should not automatically be substituted for a code-required bonding jumper without verifying the complete connection and applicable equipment requirements.

Grounding Bushings and Bonding Connections at Metal Raceway Entries

Grounding bushings provide a connection point for an approved bonding conductor at certain metallic raceway terminations. They serve a different purpose from ordinary bushings intended primarily to protect conductor insulation.

At service equipment and certain other installations, the electrical design may require additional bonding around a raceway connection. A compatible grounding bushing can form part of that arrangement.

However, not every metallic conduit termination requires a grounding bushing. The correct method depends on the raceway, enclosure, circuit configuration, and applicable code.

Where a grounding conductor must be spliced or joined, use suitable wire connectors and compression splices that are identified for the specific connection.

Selection rule: Determine the bonding requirement first, then match the bushing, jumper, or connector to the approved installation method.

Copper vs. Aluminum Grounding Connectors: Check Material Compatibility

Grounding and bonding connectors must be compatible with the conductor material and the surface they contact. A fitting intended for copper should not automatically be used with aluminum unless its identification permits that combination.

Material compatibility also affects long-term connection reliability. Dissimilar metals, moisture, and corrosive environments can create deterioration when unsuitable materials are placed together.

Some mechanical lugs are identified for both copper and aluminum conductors. Their permitted conductor combinations should be checked using the exact product specifications.

Where a project requires separate grounding or bonding conductors, coordinate the conductor selection with the relevant electrical wire and cable specifications.

Selection rule: Verify conductor material, conductor size, connection surface, and connector identification as a complete combination.

Direct-Burial Grounding Hardware and Corrosion Protection

Outdoor and underground grounding connections can be exposed to soil moisture, chemicals, and corrosion. Hardware suitable for an accessible indoor connection is not automatically approved for burial.

For example, a ground rod connection installed below grade requires a clamp identified for the applicable direct-burial conditions. A bronze or stainless steel appearance alone does not prove that approval.

Concrete-encased and corrosive locations may introduce different material and installation requirements.

Lumera's ground rod requirements and installation guide provides additional context for electrode selection and installation.

Selection rule: Confirm the final installation environment before choosing the fitting's material, construction, or burial rating.

UL 467 Grounding Equipment: Listings, Torque, and Installation

UL 467 is a standard covering several types of grounding and bonding equipment, including ground clamps, bonding devices, grounding bushings, and certain grounding electrodes.

Not every product listed in a grounding category is necessarily UL 467 certified. Verify the exact model's listing or identification against the installation requirements.

Connector performance also depends on correct installation. Follow the manufacturer's conductor-preparation, contact-surface, hardware, and tightening-torque instructions.

Where a connector's instructions require a specific torque value, use the specified installation method. A loose connection or an improperly prepared surface can compromise continuity.

Service equipment, grounding electrode connections, and other safety-critical electrical work should be specified and installed by qualified electrical professionals following the locally adopted code and equipment instructions.

Ordering Grounding and Bonding Hardware for Electrical Projects

For service upgrades, equipment installations, and industrial projects, prepare a material schedule by connection type rather than ordering all hardware under one general grounding description.

Include the following details:

• Ground clamp, lug, bushing, bonding jumper, or connector type
• Conductor size, material, and number of conductors
• Ground rod, pipe, raceway, or equipment connection dimensions
• Required listing, identification, or environmental suitability
• Mounting-hole configuration and termination method
• Exact manufacturer part number and package quantity

For larger projects, request a grounding and bonding hardware quote from Lumera Electric with the verified material schedule and required quantities.

Grounding & Bonding FAQs

What is the difference between grounding and bonding?

Grounding establishes a connection between an electrical system and earth or its required grounding reference. Bonding connects conductive parts to maintain electrical continuity and support an effective fault-current path. Both functions contribute to electrical safety, but they require hardware selected for different connections and purposes.

What is the difference between a ground clamp and a grounding lug?

A ground clamp typically connects a grounding or bonding conductor to an identified electrode, pipe, or similar surface. A grounding lug terminates a conductor at a compatible equipment connection point. Their mounting arrangements, conductor ranges, and approved uses differ. Select the connector according to the actual connection rather than treating the two as interchangeable.

Can I use a copper ground clamp with aluminum wire?

Only when the exact clamp is identified for aluminum conductors and the intended connection surface. Some connectors are rated for copper, aluminum, or both, but appearance does not establish compatibility. Check the conductor range, permitted materials, environment, and manufacturer documentation before ordering.

Do I need a grounding bushing on every metal conduit?

No. Grounding bushings are used where the electrical design or applicable code requires a specific bonding connection or where that method is selected as an approved solution. Ordinary metallic raceway connections may establish acceptable continuity when properly installed. Service raceways and certain other connections can have additional bonding requirements.

Can any ground clamp be buried underground?

No. Ground clamps used below grade must be identified for the applicable direct-burial conditions. Corrosion-resistant materials alone do not establish suitability. Check the exact product listing, conductor compatibility, connection surface, and burial environment before installing an underground grounding connection.

Does a ground rod make a circuit breaker trip during a fault?

A ground rod is part of the grounding electrode system, but earth alone is not the effective low-impedance fault-current path normally relied on to operate an overcurrent protective device. Proper equipment grounding conductors and bonding connections provide the conductive path back toward the electrical source that supports fault clearing.