Background. My sister inherited a house from her father-in-law about 3 years ago and is know experiencing some strange faults with the plumbing and electric installations. First indications was when the hot water tank started to leek, when we looked at this we found that it had completely rotted. After we replaced the tank other leeks started to appear throughout the cold water and central heating pipe work, all on the ground floor close to external / sleeper walls. She called in several plumbers who fixed the leeks as they appeared only for another to appear a week later. All the plumbers indicated that this was due to the pipes not being lagged and the acid in the lime mortar causing corrosion, although we thought that this was strange because her father-in-law had never had a water leek in all the years he lived at the property. After much deliberation she bit the bullet and had a complete new boiler, heating and plumbing system installed with every bit of pipe work replaced and lagged at great expense. Now three months on the leeks have started again, the brand new copper pipworks look like it is 20 years old and full of pinhole leeks and corrosion. I decided to take a trip over to her house and do some more investigation on the electrical installation with the following results.
First check was to see if the earth bonding was correct. This was installed although not to the current size for a PME system. Next was a Earth Loop Impedance, this came up as 400 ohm on the socket that indicated that there was a major fault, this was checked again at the main earth block and again showed a Very High impedance. We called in the supplier to check out the system and he found that the earth strap in the head end was loose, he tightened this up and left without any further tests etc. The earth impedance is now .2 ohms. My Question / Worry now is that there may still be a fault on the installation as I cant see how a faulty / no earth on the incoming supply would put a high current through the earth bonding and associated pipe work to cause the damage to the copper pipe work.
Other tests carried out Incoming cable is a 2 core 32 mm I think PAT tested all appliances, all OK Incoming mains water is Plastic When a tap is left dripping it leave a blue stain. A new electronic metre was fitted a while back, this has doubled the elec bills from previous meter and may have something to do with the fault?????
I have fitted a new consumer unit with RCD on all ground sockets, shower etc without any tripping
Any advice on how to check for neutral faults / any other faults would be appreciated and an explanation on how the earth fault would cause these problems would be greatly appreciated.