What Are Ground Bushings?

Ground bushings are threaded or raceway-compatible fittings installed at the end of a metal conduit or raceway, typically where it enters a box, cabinet, gutter, pull box, or enclosure. They usually provide two functions: mechanical protection for conductor insulation at the raceway entry and a means of bonding the raceway to the enclosure or bonding conductor. Many styles include a lug for attaching a bonding conductor, while others focus mainly on insulated throat protection. In trade use, the term may overlap with bonding bushings, but the exact product style should always be matched to the intended bonding method and the raceway system being installed.

Where Are Ground Bushings Used?

Ground bushings are commonly used on rigid metal conduit, IMC, and other threaded raceway entries into switchboards, panelboards, disconnects, wireways, pull sections, CT cabinets, and large junction boxes. They are especially common where concentric or eccentric knockouts may affect the bonding path, where a bonding jumper is specified, or where larger conductors are being pulled and insulation protection matters. They also show up in retrofit work when an installer needs to improve bonding continuity at an enclosure entry without changing the whole raceway layout. In industrial and commercial work, they are often selected for feeders, service raceways, and equipment connections where fault-current performance and inspection acceptance are more critical than on light-duty branch circuits.

How To Choose Ground Bushings

Start with the raceway type and trade size. A ground bushing has to match the conduit entry correctly, especially on threaded rigid or IMC. Next, decide whether you need only conductor edge protection or a true bonding connection with a lug. Then check the conductor range the lug can accept, the enclosure space available, and the orientation needed for practical termination. On tighter gear, lug position can matter more than buyers expect. Also consider the environment. In dry indoor electrical rooms, standard fittings are often suitable. In harsher locations, material and corrosion resistance may matter more. If the installation is part of service equipment, large feeders, or critical equipment bonding, choose a fitting with a clear intended use and install it exactly as listed and instructed by the manufacturer.

Trade Rules Of Thumb

As a practical rule of thumb, the larger the conductors and the tighter the pull, the more valuable an insulated throat becomes. Where raceways terminate into cabinets with questionable bonding through knockouts, many electricians prefer a bonding style with a lug rather than relying on locknut contact alone, subject to code acceptance and the specific fitting arrangement. Another useful rule is to think about serviceability: if the bonding conductor will be inspected, tested, or reworked later, a lugged bushing can make the connection more visible and easier to verify. These are typical field preferences, not universal code rules. Bonding method, fault path, and fitting selection must be confirmed against the Canadian Electrical Code, local authority requirements, and the equipment listing.

Sizing Guidelines

Size the bushing first to the conduit trade size, not to the bonding conductor. After that, verify the lug range if the product includes one. On larger raceways, also check whether the throat opening and shape are suitable for the conductor bundle being pulled. If multiple large conductors are entering, a smooth insulated throat can reduce abrasion risk during installation, but it does not replace proper pulling practice. Where a bonding jumper is required, size that conductor according to the applicable code rules and equipment requirements rather than assuming the lug on any bushing will automatically suit the needed conductor size. Always confirm the actual conductor range and application details on the product data before ordering.

Common Installation Practices

Typical installation starts with a properly prepared raceway end and secure locknut arrangement at the enclosure. The ground bushing is then threaded or fitted in place so the throat is seated correctly and the lug is accessible for termination. Installers usually orient the lug to avoid interference with adjacent conduits, wire bending space, dead fronts, or gutter covers. Bonding conductors should be terminated cleanly, with insulation stripped to the correct length and the connection tightened to the manufacturer torque value where provided. On larger gear, many electricians verify continuity after installation, especially where multiple concentric knockouts, painted surfaces, or retrofit conditions could affect the bonding path. Follow manufacturer instructions and approved installation methods for the specific raceway and enclosure combination.

Common Mistakes

One common mistake is ordering by conductor size instead of conduit size. Another is assuming every insulated bushing is also intended as a bonding bushing with a lug. Buyers also run into trouble when they overlook lug conductor range, material compatibility, or physical clearance inside the enclosure. In the field, poor orientation can make the lug inaccessible after adjacent conduits are installed. Another issue is relying on a fitting to solve a bonding problem without checking whether the overall raceway entry, locknut arrangement, and enclosure knockout condition support the intended bonding method. Finally, some installers treat all brands and styles as interchangeable, but dimensions, lug geometry, and intended applications can differ enough to affect fit and inspection acceptance.

Brand Comparisons

Bridgeport is widely recognized in fittings and is commonly cross-shopped where contractors want familiar trade sizing, dependable fit, and broad acceptance in standard commercial and industrial work. Hubbell is also a strong choice, particularly where buyers already use Hubbell fittings and wiring device products across a project and want brand consistency. Ortech can be a practical alternative for many standard applications where value and availability matter, provided the exact fitting style and rating match the job requirements. In the broader market, T&B and Iberville are also familiar names, and matching an existing installed brand may make sense on maintenance work or where standardization matters. The right choice is usually less about brand loyalty and more about fit, listing, lug range, finish, and whether the product matches the raceway and enclosure details on the job.

Related Products

Ground bushings are often purchased alongside locknuts, insulated bushings, bonding locknuts, rigid and IMC connectors, grounding lugs, bonding jumpers, conduit nipples, reducing washers, and enclosure accessories. On larger feeder and service jobs, buyers may also need wire pulling lubricant, conductor markers, grounding bars, and cabinet bonding hardware. If the application involves raceway transitions or unusual enclosure entries, it is worth checking the full fitting stack-up before ordering so the bushing, locknut, and raceway components all work together without clearance issues.

Frequently Asked Questions

Are ground bushings and bonding bushings the same thing?

Not always. In trade language the terms are sometimes used loosely, but some products are mainly for conductor protection while others are specifically intended to provide a bonding connection, often with a lug. Check the product description and intended use before ordering.

Do I need an insulated throat on every conduit entry?

No. The need depends on the raceway type, conductor size, pull conditions, equipment design, and applicable code requirements. In practice, insulated throat styles are often preferred on larger conductor pulls because they can reduce the chance of insulation damage.

How do I size a ground bushing?

Match the bushing to the conduit trade size first. Then verify any lug conductor range, enclosure clearance, and application details. Do not size the fitting only by the bonding conductor.

Can I mix brands of bushings and other conduit fittings?

Often yes, but only if the components are compatible and suitable for the installation. Dimensions, thread fit, lug orientation, and listing details can vary. On critical work, many buyers prefer to confirm compatibility before ordering mixed brands.

When is a lugged ground bushing a better choice than a plain bushing?

A lugged style is often preferred when a visible, deliberate bonding connection is needed, especially on larger gear, service raceways, or installations where knockout conditions may make the bonding path less straightforward. Final selection should follow code and equipment requirements.

Are these mainly for rigid conduit?

Many common ground bushings are used with threaded rigid metal conduit or IMC, but the exact application depends on the fitting design. Always confirm the raceway compatibility listed for the product.