Water pipe as earth electrode?

[Gerry24]

Been asked to quote for a CU replacement in an old rectory. First quick look (no time to do any yests yet) shows supply is from 2 separate cables from the other half of the house (house split into 2). Assumed the 10mm earth conductor that is installed on the CU led to an earth electrode but it leads to the water pipe under the kitchen sink. No other earth conductor!!!

Never seen this before. Am I missing something obvious here or are the water pipes acting as the earth electrode? I'm sure it says in the regs that you can't use water pipes as earth electrodes in a domestic installation.

 

[Sparky Ninja]

Have a read of the regs in question, all will be revealed.

 

[sparks_114]

You can use the water pipe as an earth electrode under the condition that it is privately owned (not utility) and meets certain criteria (it has been considered for such use, etc). Consult regulation 542.2.4

 

[anton1210]

simplified, there should be a 10mm earth to the water and gas services etc, and a main earth (size depending on system) IF PROTECTED BY 30mA RCD. if not on 30mA rcd then it will be the old EEBADDS system where everything is cross bonded. no service pipe should be used as a main earth.

 

[Knobhead]

There was electricity before the 17th edition. The use of utility pipes only was common practice. The steel gas pipe was often a better earth than the lead water pipe.

It was with the introduction of plastic utility pipes this really became a problem. (Well there was the odd problem with the occasional electrocuted plumber or gas fitter, but hey ho, who cares about them).

 

[Gerry24]

Thanks for your replies. There was also a gas pipe but no earth/bond to that. Could not find any cross bonding between gas and water pipes. I will ask the customer about their water supply but I'm pretty sure it will be from the 'mains' i.e. Severn Trent Water.

Looks like I am going to have to install an earth electrode(s). I will take a Ze reading of the existing earthing arrangements when I go back to see what the value is out of curiosity.

 

[Knobhead]

To add to my last post. I had to dig up part of my back garden to put in a new drain. I came across the redundant steel gas pipe that originally fed the house only 18” from the earth spike, soon linked them together with some 25mm singles. To hell with the reg’s 500’ foot of steel buried in the ground wasn’t going to be wasted.

 

[SPARTYKUS]

To add to my last post. I had to dig up part of my back garden to put in a new drain. I came across the redundant steel gas pipe that originally fed the house only 18” from the earth spike, soon linked them together with some 25mm singles. To hell with the reg’s 500’ foot of steel buried in the ground wasn’t going to be wasted.

Nice bit of common sense there

 

[Engineer54]

To add to my last post. I had to dig up part of my back garden to put in a new drain. I came across the redundant steel gas pipe that originally fed the house only 18” from the earth spike, soon linked them together with some 25mm singles. To hell with the reg’s 500’ foot of steel buried in the ground wasn’t going to be wasted.

Tut tut, ...what's this?? Is someone actually saying to hell with the the Reg's?? ....haha!!!

Yep, ....there are many occasions when/where commonsense and your competence in what your doing, will make much more sense, than what is written in the ''cover-all'' Reg's....