High ZE compared to SSE figures on a TN-S

Hi, I'm carrying out a periodic EICR on a factory, can any inform me of the correct procedure for gaining a ze at  origin as I have always used the 2 wire method with main earth removed as stated in the on site guide, I have a reading of 0.77 ohms on a TN-S which is no where near the 0.22 ohms that SSE has recently recorded as they had to attend to the newly installed service head ( 5 years old ) due to some loose connections. The only way that I can get my readings that low is to use the 3 wire method.

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  • At least one of the meters is giving an erroneous reading. When was the calibration of yours last checked please?

    Which value seems more credible? For comparison, my Ze at home is around 0.23 Ω - 100 A TP PME supply. The nearest transformer is about 100 metres away, of which 90 are the street main. AFAIK, the transformers are in a network rather than a straight line, but that may give you a rough idea of what to expect.

  • My meter has recently been calibrated, both readings are accurate as they were tested in different ways, 2 wire between L/E, 3 wire between L/E/N. 

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