My local water authority recently changed all the old metal pipes in my area to plastic, since then I have sometimes received small, tingling sensations from my sink, dishwasher and washing machine. I am assuming these appliances were originally earth bonded to the metal pipes and this is no longer the case. Can anyone suggest a solution i.e can I bond to the gas pipes and how is this done? thanks
Electric shock from sink ?solution
- Thread starter cape65
- Start date
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You need to get an electrician in ASAP - maybe post on their forum too. Plumbers have been killed cutting through underground metal water pipes when there is a dodgy "current leak to earth". That "tingle" could turn nasty without warning.
I'm assuming the sink was originally supplementary bonded via the main cold incomer?
Changing to plastic piping sounds like the earth fault path has been broken.
The main earth to the house will usually either be via an earth rod to ground or by using the sheathing of the incoming underground feeder cable. I'm not sure the water authority work would affect your earthing arrangement but it's worth looking into getting an earth rod installed if you haven't already got one.
FYI:
Typically, there are earth bonds required from the earth terminal of your distribution board (seperate links). One to the main cold incomer (consumer side of stop tap), and one to the gas (consumer side of meter).
Supplementary bonding should then be carried out by linking hot&cold pipes under the kitchen sink (and linked to sink) and bathroom sink (linked to radiator and bath if steel).
Linking all pipes feeding your boiler is a good idea also.
All cabling in 10mm using approved earth clamps and cable lugs.
Sorry for the essay but it's worth giving the info so you can check everywhere anyway.
When alls said and done, 100% agree, get an NIC/EIC electrical company in to investigate.
Changing to plastic piping sounds like the earth fault path has been broken.
The main earth to the house will usually either be via an earth rod to ground or by using the sheathing of the incoming underground feeder cable. I'm not sure the water authority work would affect your earthing arrangement but it's worth looking into getting an earth rod installed if you haven't already got one.
FYI:
Typically, there are earth bonds required from the earth terminal of your distribution board (seperate links). One to the main cold incomer (consumer side of stop tap), and one to the gas (consumer side of meter).
Supplementary bonding should then be carried out by linking hot&cold pipes under the kitchen sink (and linked to sink) and bathroom sink (linked to radiator and bath if steel).
Linking all pipes feeding your boiler is a good idea also.
All cabling in 10mm using approved earth clamps and cable lugs.
Sorry for the essay but it's worth giving the info so you can check everywhere anyway.
When alls said and done, 100% agree, get an NIC/EIC electrical company in to investigate.
H
HuwG
Grundfos got taken to account for a pump issue a few years back, when an installer was killed by one of their products.
Huw.
Huw.
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As I've already said in the electrical forum, this could be a far more serious fault than a simple lack of bonding.
When the pipework entering the house was metal, it would have had the ability to introduce an external electrical potential into the house, hence being an extraneous conductive part and the need for bonding. Although we still bond plastic incoming water mains, we only do so at the point where it becomes copper, and more and more often this doesn't happen until inside the house. If anything, your new pipework should be less likely to introduce an external potential.
I suspect that, in actual fact, the water main coming into your house had previously been providing your main earth connection. As it is now non-conductive, any earthed metal parts in your house connected to the electrical installation are free to float at whatever potential they wish with respect to true earth. Worst case scenario is that a Live-Earth fault could develop - this would cause all earthed metal parts to become live, but because of the lack of an earth connection, the protective devices in the installation would be unlikely to operate.
Right now, you're probably just receiving a tingle from currents that are capacitively coupled into the earth, as well as the current dumped there through filters in switch mode power supplies and the like as found in computers. If a more serious fault were to occur, all metal parts could become live at 230v and provide far more than a tingle.
The fact that you're getting shocks from the sink AND the dishwasher/washing machine lends even more credibility to this theory, as they will only be linked to the water main by means of a plastic pipe. The water in the pipe over the length of the flexible hose would be unlikely to be conductive enough to introduce a potential into the metal casing of these machines. Even if it did, the presence of a true earth connection would prevent the voltage on the casing rising to the point where it's able to give you a shock/tingle.
I expect if you were to touch other earthed metal parts such as the screws on your sockets, you'd receive this same tingle.
I think you need the installation checked over by a spark as a matter of urgency. As a bare minimum, he should perform an earth loop impedance test to determine the Ze of the installation.
When the pipework entering the house was metal, it would have had the ability to introduce an external electrical potential into the house, hence being an extraneous conductive part and the need for bonding. Although we still bond plastic incoming water mains, we only do so at the point where it becomes copper, and more and more often this doesn't happen until inside the house. If anything, your new pipework should be less likely to introduce an external potential.
I suspect that, in actual fact, the water main coming into your house had previously been providing your main earth connection. As it is now non-conductive, any earthed metal parts in your house connected to the electrical installation are free to float at whatever potential they wish with respect to true earth. Worst case scenario is that a Live-Earth fault could develop - this would cause all earthed metal parts to become live, but because of the lack of an earth connection, the protective devices in the installation would be unlikely to operate.
Right now, you're probably just receiving a tingle from currents that are capacitively coupled into the earth, as well as the current dumped there through filters in switch mode power supplies and the like as found in computers. If a more serious fault were to occur, all metal parts could become live at 230v and provide far more than a tingle.
The fact that you're getting shocks from the sink AND the dishwasher/washing machine lends even more credibility to this theory, as they will only be linked to the water main by means of a plastic pipe. The water in the pipe over the length of the flexible hose would be unlikely to be conductive enough to introduce a potential into the metal casing of these machines. Even if it did, the presence of a true earth connection would prevent the voltage on the casing rising to the point where it's able to give you a shock/tingle.
I expect if you were to touch other earthed metal parts such as the screws on your sockets, you'd receive this same tingle.
I think you need the installation checked over by a spark as a matter of urgency. As a bare minimum, he should perform an earth loop impedance test to determine the Ze of the installation.
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