How to Terminate a Cable Lug onto an Earth Bar

The correct way to terminate the Cable Lug onto an Earth Bar seems to cause confusion in the industry. For instance, a very common question we hear is: should the cable lug be bolted face down directly onto the actual copper bar or should the cable lug be placed ‘floating’ between the nuts? This article from A.N. Wallis aims to highlight the recommended connection instructions that eliminate the common mistakes being made during installation and termination of a cable lug on an earth bar.

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Earth Bar Termination Components

Before talking about the correct installation, it is important to look at the actual termination components of the Earth Bar and know what these are:

Each typical AN 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)

When manufactured, the combination of components are assembled on an Earth Bar in the following order:

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

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Recommended way to terminate a Cable Lug onto an Earth Bar

To begin with, our recommended way for the termination/ installation/ connection of the cable lug onto an Earth Bar is to ‘fix’ the flat side of the cable lug directly to the actual copper bar. This method allows for full contact between the connecting cable and the Earth Bar and prevents any reduction in cross-sectional area. Therefore, based on the components supplied on a AN Wallis Earth Bar, we recommend the ‘fixing’ to be made in the following combination (as detailed in the below 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, when fixing down a cable lug having the spring washer and one nut should be absolutely fine. However, AN Wallis like to go above and beyond therefore they supply two nuts! The second nut acts as a lock against the first nut, making the installation even more tight, secure and safe.

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Incorrect way to terminate a Cable Lug onto an Earth Bar

There are occasions where people incorrectly assume that the supply of two nuts must be used to ‘sandwich’ the lug in between the two. For example, the lug ‘sitting’ on one nut and tightened up by the other. This is not correct and not recommended at all! This method does NOT allow full contact to be made between the connecting cable and Earth Bar, therefore the actual cross-sectional area is reduced.

We can think of two reasons to use this incorrect method – Firstly, it could be a lack of knowledge/training on the correct installation procedures. Secondly, it could be ‘laziness’ of the installation contractor, wanting to save some time and effort by not fully disassembling the termination components to attach the lug and reassemble correctly. This may save slight installation time, but it is incorrect and more importantly, unsafe!

In conclusion, the recommended way for the termination/ connection of the cable lug onto an Earth Bar is to ‘fix’ the flat side of the cable lug directly to the actual copper bar. That way the cable lug is directly in contact with the actual copper bar. This method allows for full contact between the connecting cable and the Earth Bar and prevents any reduction in cross-sectional area.

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A.N. Wallis Earthing Solutions