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Old Iron Underground Gas Pipe Earthing.

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I came upon this installation today. There is no P.M.E. earth terminal but just a TT rod outside. Ze is about 15 Ohms. But even accounting for the rain recently I can not see that a single 4ft. rod can achieve that low a Ze. The old Denso tape covered iron gas pipe runs underground to the road. It is bonded inside the house as is (presumably) the water pipe. The house is a 1930s aged property. I am noy happy about the final circuits in the consumer unit that do not have R.C.D. protection. Some of these supply outside metal lights on the bungalow wall. I can't imaging in the 80s or 90s this arrangement ever complying. Is the installation relying on the old gas pipe as an earth electrode? I could not do a thorough test today as the gas man was servicing the gas boiler.

Comments please?

Parents
  • 0

    If it really is TT then it never complied. A 30 mA RCD up front is the easiest fix. Why Ze is so low is a mystery you are unlikely to solve and there is little point anyway. In Bristol there are quite a few like this, where Earthing is quite marginal, and the age of the head is probably 60s so perhaps no one has done much for a long time. I assume the supply is overhead from the Brown incomer cables?

Reply
  • 0

    If it really is TT then it never complied. A 30 mA RCD up front is the easiest fix. Why Ze is so low is a mystery you are unlikely to solve and there is little point anyway. In Bristol there are quite a few like this, where Earthing is quite marginal, and the age of the head is probably 60s so perhaps no one has done much for a long time. I assume the supply is overhead from the Brown incomer cables?

Children
  • 0 in reply to David Stone

    Indeed David, new overheads with P.M.E. earthing available on request. Fortunately the house owners are having a new E.V. charging point and a new consumer unit installed soon.

    Z.

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