18.08.16
Technical center ZANDZ.com has been working for more than 10 years in training of organization of proper grounding and lightning protection. During this time, we have been giving tips and advice on installation and assembly of high-quality protection. The existing base of calculation examples, regulations and instructions, everyone can find answer to his question. And today, adding to the archive of knowledge, we answer the question of our readers.
Question:
There is a well-grounded water pipe in an old two-storey house apartment (voltage: zero-phase 226 V;-phase pipe 228V;Resistance: zero-pipe 15 - 20 ohms). The first floor, two apartments: iron input, plastic pipe routing; and the second floor, two apartments: routing is presumably iron. There is no potential equalization. If to ground the pipe on the first floor, for example, washing machine similar to the TT system through the RCD 30mA, than it can threaten the neighbors from above?
Answer:
Grounding must be carried out in accordance with the grounding system used in the house, which means that all the residents must use the same grounding system as well as potential equalization system correctly executed in accordance to paragraph 1.7.82 of the EIC 7 edition. It is allowed to use a water pipe as a natural grounding, if it is included in the potential equalization system. But in this case, correctness of grounding means grounding the main grounding bus and not on extraneous conductive parts, which is a water pipe. The danger lies in the fact that at the damage of the insulation, there appears potential on the pipe and the neighbors, having no potential equalization system, could fall under dangerous voltage.
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