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Correct Termination Of A Cable Lug Onto An Earth Bar | AN Wallis Guide

Posted on 08 July 2022

Earth Bars

AN Wallis designs, manufactures and supplies thousands of Earth Bars per year, it is one of our ‘core’ product ranges. This has given AN Wallis many years of history and experience dealing with Earth Bars and puts us in a good position to answer any questions or queries on the subject or topic of Earth Bars.

One question we often get asked is to clarify the correct way to terminate a cable lug onto the actual Earth Bar? For instance, 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?

The correct way to terminate the cable lug onto an Earth Bar seems to cause confusion so the purpose of this article is to give our recommended installation instructions to eliminate the common mistakes being made during installation.

Before we begin to talk about the correct installation, we think it is important to look at the actual termination components of the Earth Bar and know what these are.

Wallis Earth Bar Software

 

Each typical AN Wallis ‘standard’ termination point consists of the following components.

  • 1 No. x M10x35 Phosphor Bronze Hex Head Set (7)
  • 1 No. x M10 Phosphor Bronze Flat Washer (4)
  • 1 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

Terminate the Cable Lug onto an Earth Bar

Our recommended way to terminate 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 to be made between the connecting cable and the Earth Bar and prevents any reduction in cross-sectional area.

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

Correct way to terminate onto an Earth Bar

Our recommended way to terminate the cable lug onto an Earth Bar is to ‘fix’ the flat side of the cable lug directly to the actual copper bar.

Under normal circumstances, when fixing down a cable lug having the spring washer and one nut should be absolutely fine, however, at AN Wallis we like to go above and beyond therefore we supply two nuts! The second nut is to act as a locking nut against the first nut making the installation even more secure and safe.

There are occasions where people incorrectly assume that the supply of two nuts must be used to ‘sandwich’ the lug in between the two i.e. 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 for full contact to be made between the connecting cable and Earth Bar, therefore the actual cross-sectional area is reduced.

Incorrect way to terminate onto an Earth Bar

We can think of two reasons why this incorrect method might be used. Firstly, it could be a lack of knowledge/training on the correct installation procedures, and 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!

Our recommended way to terminate the cable lug onto an Earth Bar is to ‘fix’ the flat side of the cable lug directly to the actual copper bar.

To conclude, our recommended way to terminate the cable lug onto an Earth Bar is to ‘fix’ the flat side of the cable lug directly to the actual copper bar so that the cable lug is directly in contact with the actual copper bar.

This method allows for full contact to be made between the connecting cable and the Earth Bar and prevents any reduction in cross-sectional area.

Correct way to terminate onto an Earth Bar


Thorne & Derrick and AN Wallis are aware of the crucial role of an Earth Bar which is why they manufacture high quality, affordable earth bars that are designed and tested to all relevant standards – manufactured from hard drawn copper bar to BS EN 13601 and tested to BS EN 62561-1 Class H.

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