Live Electrical Testing

Live electrical testing! Something I have spoken about across social media for years and years. Most recently sharing videos and discussion from Tiktok to twitter. A recent Linkedin poll with over 1000 responses showing 90% of responders agreed with the need for test measurement to be made live.

Primarily because a lot of apprentices and newly qualified electricians are telling me they have little training and experience with live testing. When its appropriate and how to do it safely.

We often discuss deskilling within the electrical industry and I hope very much this isn't another one of those!

Do not get me wrong we have a very valuable and sometimes appropriate method of calculation using data from dead tests. Some refer to this as The Zs test with no acceptance or understanding of the importance of taking a measurement in some situations. I want to outline some of those here as one or two individuals have persistently insinuated things such as I want on load testing with motors running... This is an attempt to devalue my own work experience and knowledge. I prefer to debate subjects rather then try to discredit individuals so I wont hold to much value in those insinuations.

We need to remember why we test, primarily to ensure safety and that no mistakes through the construction phase are left in place. Also that design parameters have been met. We can achieve that a number of ways. On simple domestic/small commercial installations with a small pool of workers utilising the calculation method can be entirely safe and valid. The only benefit of live testing in this situation been a final check for mistakes made through the dead testing process and an accurate recording of true circuit impedance.

On more complex installations with multiple workers/inspectors a final live measurement would always be my suggested method. It ensures as far as possible end users are kept as safe as possible. I have caught many of my own mistakes never mind others using this system of works over 25 years now.

Also in complex industrial and field based installations a measurement of circuit impedance can be mandated by equipment manufacturers and are essential to verify the safe operation of over current protective devices.

I have seen EICRs carried out with the calculation method and these reports stating maximum Zs has been exceeded. Primarily due to the 80% rule of thumb or temperature corrections. When a direct measurement is made the value complied with the above same rules. This is a particular problem with long cable runs and heavy load equipment.

My own experience in the military sector which sometimes has temporary installations alongside more permanent ones when again measurement is essential. We also see similar situations in Rail, Generation, heavy plant and even large commercial.

Focus is rightly applied to regulation 14 of the electricity at work regulations. We should be limiting all live working to an absolute minimum to ensure safety of electrical workers. But EWR 1989 has more than one regulation and we need to ensure we meet ALL of them. This will at times make live electrical testing essential, this applies to RCD and Zs testing.

We also need to be aware of the importance of the data we present on electrical certification both EIC and EICRs. If we make observations based on calculated values that turn out not to be accurate and remedial works result we now have a commercial liability based on the information we presented. So we need to be very clear on these reports what the information provided means.

Finally and most importantly we need to be honest about what live testing looks like. We do not need to expose ourselves to live parts in 99% of cases. It is a total myth. These values can be obtained in a very safe way by using appropriate adaptors and leads. I think it is essential we provide apprentices and new electricians with the training and skills to carryout these tests safely. Or do we want them stood attempting to do it using unsafe methods through a lack of training/knowledge?

I produced another video of very quickly, simply and safely gathering an earth fault loop impedance measurement here https://youtu.be/XX19KED5v7E I have several others as well. Along with videos about calculating Zs.

It is offensive to see the personal nature of some responses to my musings on social media about this of late. Suggestions of on load RCD testing, Testing with motors running, unsafe practices promoted and such. Often spinning angles of discussion that are simply not true to drive an agenda based on ideology and trying to diminish others points of view.

This article is aimed at supporting electricians of the future with the valuable knowledge they could need to keep them safe and in full compliance of relevant stands and regulations. Live testing for Zs measurements only has to be exposing yourself to increased risk if you are not aware of safe methods.

As always the above is based on respect, kindness, guidance and support. It comes from a place of wanting to share knowledge, debate subjects and increase the skills of my brother and sister sparks of the future.

Thanks for reading and stay safe out there!