We have an earthing issue in our grandfathers house. He has been getting a shock through the taps & water in the bathroom. I did some investigation and found 2 issues.
1 a faulty appliance
2 an interrupted earth (earthed via cold water feed interrupted by plumber putting plastic stop tap on)
I have put an earth strap to jump the offending plastic and isolated the faulty appliance ready for renewal.
my question is "Do I need to do anything else? ie. bond metal fittings in the bathroom to the earthing system. If this needs doing where do I earth them to?
the cold water feed (as is the existing earth)
into an electric socket outside the bathroom Which would be the safest option to ensure my grandfathers safety, or would it be safer not to fit supplementary bonding at all.
Thank you for reading any information would help. regards christine .
Sounds prefectly sensible. Actions like these could save someone's life.
The bathroom usually has what is known as "supplementary bonding" where all local extraneous[1] metalwork and local circuit[2] earths are bonded together within (or at least very close) to the bathroom.
[1] Bits of metal that exist in the bathroom and also go through to another room or area - eg metal pipes. This does not include wholly contained bits of metal like shelves - but would include radiators and their feed pipes.
[2] circuits that come into the bathroom - typically your lighting circuit but possibly also another circuit for say an electric shower or wall heater.
Shaver sockets and extractor fans may be (but not always) supplied from the bathroom's lighting circuit - best not to make assumptions here.
This is a better and more complete explanation:
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1. the cold water feed (as is the existing earth)
The requirement for supplementary bonding has gone in the latest wiring regs
- *provided* certain other conditions are met. It would be safer to assume you DO need it in your house.
It might be worth asking a registered electrician in to check it over as it's hard to give absolutely correct answers without being able to see stuff.
But you have some idea what to expect.
Do you have any other shower rooms or bathrooms that should be checked too?
Bathrooms should have either equipotential bonding, or all supplies into th= e room should have RCD protection. If he's had a shock he has neither.
Also an appliance fault shouldn't cause this, it normally takes 2 faults in= the appliance for it to make pipework live.
It sounds like a neglected installation, household appliances with multiple= faults still in service, and probably never checked. Its not hard to add e= quipotential bonding, main earth bonding, and easy enough to do some basic = checking & testing of all appliances to pick up on any in need of attention= . You could check all flexes are wired, fused and gripped properly at each = end, and use a multimeter to check for any L&N to E leakage. More can be do= ne, whether you think it worthwhile is a judgement call.
Niether fault on their own but both together do. The plumber who fitted the plastic stopcock and did not maintain the electrical conductivity across it need his goolies attaching to the floating pipe work with that fault appliance plugged in and switched on.
Perhaps not, it would be wise to get the REC to come in and check that they are supplying a proper main earth terminal. Note the REC, this is a supply issue and their problem.
If the main earth terminal was functioning, an MCB or RCD should have operated - regardless of the state of bonding to the plumbing.
Maybe, maybe not. It depends if the earth fault is supply side or not. The fault may only be on the circuit to which the faulty appliance was connected (and is apparently bonded to part of the plumbing).
- regardless of the state of bonding to the plumbing.
fault may only be on the circuit to which the faulty appliance was connected (and is apparently bonded to part of the plumbing).
I was appalled to find our house was using the water main as an earth. We are on a TT system and there is no supplied earth so I did get a spike installed (and a split RCD board).
Faulty and probably unearthed itself by the sounds of it...
For clarification are you saying that the only method of earthing in the property is the cold water pipe?
Are you able to identify the type of earthing it should have from the options described here:
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I have put an earth strap to jump the offending plastic and isolated the
Probably - but it depends a bit on the answers to the above questions.
There is no specific requirement for this - although it tends to happen by default. The bathroom should have supplementary bonding.
The building should have main equipotential bonding.
It may require a main earth connection upgrade or installation.
It may require one or more RCDs.
In the event of other faults, the supplementary bonding will protect you from life threatening shocks when you are at potentially you most vulnerable (i.e. wet etc)
It sounds like a fairly detailed review of the whole installation is in order.
The concept of a "main earth terminal" is fairly recent. It's not that long ago (in terms of the life time of supply installations) that it was normal practice for an installations earth to be via the water suuply pipe.
Well as people were getting shocks with the unbypassed plastic valve in the water supply the installation must have a faulty "main earth terminal" as you point out above.
I don't think that is a very likely scenario, possible but not probable. Far more probable is that the installtion doesn't have a properly supplied main earth terminal.
Do you mean the quoting? Usually you just have to press carriage return to start your reply and it'll have the right 'color'. Probably depends on your newsclient/web_interface. Also, it's considered good practice to delete a bit if it gets too much to comfortably read/find the reply...
Ah, I see you are using DIYbanter - that may explain the difficulty you are having with the quoting of messages. Most of us are using a proper newsreader program to access the usenet group uk.d-i-y which is nothing to do with diybanter really - it just sucks content from the group and allows people to post to it group using a web based interface. The newsreader programs take care of all the quoting etc while being somewhat quicker and easier than using web forum type interfaces to usenet.
The "colours" as such as just a way the interface you are using try to highlight the words of different posters. Alas if you explicitly attempt to apply colours using diybanter, most of us won't see them! (which is why I am having to guess a bit at what bits were your post and which bits were Dave's)
Have a read of:
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may make it a bit clearer what is going on.
ok that would make sense. Older TT systems frequently did not have a dedicated earth connection. This is a practice that can be safe (as long as there is (as a minimum) a VO ELCB or (preferably) a RCD, but its strongly deprecated, since its not uncommon for a supply pipe to get replaced with a plastic one, and suddenly your decent earth has now vanished.
ELCB looks like:
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like:
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Almost certainly (see the RCD spur picture in the RCD article above)
The REC is basically your electricity supplier - not necessarily the people you buy it from - but the company responsible for the actual physical wires etc. What would have been your local electricity board in days gone by.
Now if you have a TT supply, it may be that the supply company are not able to provide you with an earth connection at all. In which case it becomes your responsibility to maintain a proper TT system with your own earth connection (typically and earth rod) and RCD protection for *all* the circuits in the house. (you can't rely on a local earth rod offering a low enough resistance connection on its own to clear an earth fault - so the RCD is mandatory)
Which is good. However don't assume that you have corrected all the defects at this point.
Yup and enquiry to then to find out what (if any) earthing they can supply would be sensible. Many parts of the network that at one time were not able to supply an earth (rural areas typically) have been upgraded to be able to support TN-C-S earthing (PME). So that may be an option, and they may be able to fit an earth connection from your supply to your installation.
(I have a TT setup here - but the supply was upgraded later, and would now support TN-C-S should I wish to use it as such)
Do 3 before 2 I would suggest since it may add new options.
Seems like a sensible approach.
It sounds like from what you have described, that you may have a TT install, with an inadequate earth provision, and no proper RCD protection either.
If this really is the case, then it a serious issue that does merit
*urgent* attention.
The earthing / no rcd issue, could result in faults which leave any earthed metalwork in the house "live", with no realistic possibility that the fuses / circuit breakers alone would be able to disconnect the supply. This is obviously a serious electrocution risk.
The lack of supplementary bonding also means there is no safety net that could protect you from the effects of the first problem! (normally it will mean even if something is live that should not be - it is clamped to the same voltage as anything else you can touch - thus vastly reducing the risk of a serious shock)
It might be helpful if you could post some photos of the supply head end (i.e. the main cutout, tails, meter etc) and the consumer unit - it will at least give us a feel for what we are dealing with. (you can post these via diybanter if you want - we should be able to see those)
The cost to rectify the problems could vary dramatically. If you are in a location where the supplier can provide a TN-C-S/PME supply, then that along with the addition of main and supplementary bonding, may be just about enough. However RCD protection for at least circuits powering sockets would be a very sensible addition. A consumer unit replacement may be a more sensible way of resolving many of the issues however, and that could add several hundred to the costs.
You need to have a "Competent Person" look at this on-site, and to bring th= eir test gear with them too.
This is uk.d-i-y, so we recognise that a competent person might be yourself= , not just a full-time professional sparky. However you do have to be _comp= etent_, which is almost certainly going to mean some study beforehand.
At the very least (ie you're risking your grandfather's safety otherwise) b= uy yourself a copy of an "On site guide" for the 17th edition (ten-twenty q= uid, Amazon or an electrical wholesaler). This describes acceptable install= ation and testing practice.
The system really needs a thorough test. Faults like this accumulate over t= he years and it's likely that this wasn't the only one. There are also issu= es of old systems not being to current standards, even if they're perfectly= adequate to old standards. There should have been an RCD here, it should h= ave tripped, and it would be prudent to consider adding one.
I don't understand how an appliance fault and an isolated tap turned into a= shock. Possible, depending on the appliance, but not obvious. So I'd still= be looking for other possible causes.
Also remember that _we_ know nothing. If we weren't restricted to looking a= t it in ASCII, some of us might do, but on the Interwebs, no-one knows you'= re a dog. Even Adam, who is a real sparky, can't see or measure at your gra= ndfather's house.
Aplliance live to earth short. The "tap" in question was the main stop c*ck with the only earth bonding for the electrical system up stream of the tap. Thus all the house pipe work is floating and connected to live via the appliance fault. There will be some current flow to earth but no wherer near enough to blow a fuse or trip an MCB. With limited current flow the volts on the plumbing might not rise to full live potential but could certainly approach it.
I agree that the supply and installation does need a good look at and I'd start with supply and the main earth terminal from the REC. Once that is sorted out, either as a PME or TT installation further action on the installation can be decided upon.
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