Daniel asks this question, which concerns a new caravan tested for its external loop impedance (Ze), which was found to be too high – what to report on the Electrical Installation Condition Report (EICR)? It has been answered by the ECA (Theme - Testing, Tools and Equipment):
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Question: I was testing a static caravan other day and found that when the Ze is tested at the caravan’s consumer unit – the result is a high 130 ohms. I then went out and tested at the hook up point, with the result that the Ze was again found to be the same.
Now I am stuck to give certificate whether this electrical installation satisfactory or unsatisfactory.
It is a brand new caravan and inside, the installation is sound - and dead test result are all good, as is even the live test, and when I carry out the RCD test - all comply with the regulations.
The hook-up point has an RCD and inside the caravan also has an RCD. I noticed that the hook-up point has been supplied with two-core SWA cable, and armoured cable is used as the earth, which is why the Ze reading is so high.
Now, can you please advise me as to whether I should show the EICR as ‘satisfactory’ or ‘unsatisfactory’, and I will inform the caravan club that the earthing system needs to be upgraded, and I will put this in my test sheet as well. So, what should I do?
Answer: The first point to note is that you haven’t stated whether the earthing system is TT system or not – which is it?
Even so, 130 ohms is high and may not be stable, so you should inform your client to get the earthing system fully inspected and tested further.
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