How to Terminate a Cable Lug onto an Earth Bar

Thu 6th Oct 2022

The proper method for terminating a Cable Lug onto an Earth Bar is often a source of confusion within the industry. Frequently, we are asked whether the cable lug should be bolted face-down directly onto the copper bar, or positioned ‘floating’ between the nuts. This A.N. Wallis-themed article provides clear guidance on recommended installation practices, helping to eliminate common errors when terminating cable lugs on earth bars.

Earth Bar Termination Components

Before we dive into proper installation, it is essential to understand the individual termination components of the earth bar and their functions.

Each typical A.N. Wallis ‘standard’ termination point consists of the following components:

• 1a No. x M10 x 35 Phosphor Bronze Hex Head Set (7)
• 1b No. x M10 Phosphor Bronze Flat Washer (4)
• 1c No. x M10 Phosphor Bronze Spring Washer (8)
• 2 No. x M10 Phosphor Bronze Full Nuts (5)

During manufacturing, the components are assembled onto an Earth Bar in the following sequence:

Hex Head Set → Flat Washer → Nut → Spring Washer → Nut

Recommended Way to Terminate a Cable Lug onto an Earth Bar

Our recommended method for terminating or connecting a cable lug to an Earth Bar is to ‘fix’ the flat side of the cable lug directly to the actual copper bar. This approach ensures full contact between the cable and the Earth Bar, preventing any reduction in the effective cross-sectional area. Based on the components provided with an A.N. Wallis earth bar, we advise assembling the connection in the following sequence (as shown in the adjacent picture):

1. Lug over the Hex Head Set (in direct contact with the Copper Bar)
2. Flat Washer
3. Spring Washer
4. Nut
5. Nut

Under normal circumstances, securing a cable lug with a spring washer and a single nut is sufficient. However, A.N. Wallis goes a step further by supplying two nuts. The second nut acts as a lock against the first, providing an extra level of security, ensuring a tighter, safer and more reliable connection.

Incorrect Way to Terminate a Cable Lug onto an Earth Bar

Occasionally, installers incorrectly assume that the two supplied nuts should be used to ‘sandwich’ the cable lug — placing the lug on one nut and tightening it with the other. This method is incorrect and NOT recommended, as it prevents full contact between the cable and the Earth Bar, reducing the effective cross-sectional area of the connection.

There are two main reasons why this incorrect method is sometimes used. First, it may stem from a lack of knowledge or training on the correct installation procedure. Second, some installers may attempt to save time and effort by not fully disassembling the termination components before attaching the lug. While this approach may seem faster, it is both incorrect and unsafe, compromising the integrity of the connection.

In conclusion, the correct method for terminating a cable lug onto an Earth Bar is to fix the flat side of the lug directly onto the copper bar. This ensures full contact between the cable and the Earth Bar, maintaining the full cross-sectional area and providing a safe, reliable connection.

A.N. Wallis Earthing Solutions

A.N. Wallis designs, manufactures and supplies thousands of Earth Bars each year. With this extensive experience, the company has developed deep expertise in Earth Bars and is well-positioned to provide guidance on earthing protection. In addition to Earth Bars, they offer a comprehensive range of earthing protection products and solutions:

EARTHING BARS

EARTH RODS

EARTHING CLAMPS

ROD COUPLERS

DRIVING HEADS

ACCESSORIES