On another forum (Wiki) a post was put up, "filling tanks when connected to the mains", muggsie here interpreted this wrong, but it brings up a question. A while back some of you may remember a girl who turned on the outside tap and suffered electrocution, and permanent damage. I was told that the mains water can become live, if there is an earth fault on the appliance you are using and if a house etc. down the road has an earth fault and is earthed to a copper pipe. Its all because of the plastic tubing used these days, the water becomes a conductor.
So with your van or motor home insulated from earth via rubber tires and jockey wheel, and a faulty earth at the mains box where your extension lead plugs in, is it possible for the water in your RV to become live ?
On another forum (Wiki) a post was put up, "filling tanks when connected to the mains", muggsie here interpreted this wrong, but it brings up a question. A while back some of you may remember a girl who turned on the outside tap and suffered electrocution, and permanent damage. I was told that the mains water can become live, if there is an earth fault on the appliance you are using and if a house etc. down the road has an earth fault and is earthed to a copper pipe. Its all because of the plastic tubing used these days, the water becomes a conductor.
So with your van or motor home insulated from earth via rubber tires and jockey wheel, and a faulty earth at the mains box where your extension lead plugs in, is it possible for the water in your RV to become live ?
There are quite a few ways in which you can get a shock from your van , when your van is plugged into an earthed power socket even with power "OFF".
It is due to ground voltages in mother earth itself, often due to a faulty neutral connection somewhere in the electrical system.& not necessarily yours
Its the potential of both . Chances are the water tap is a good earth and theres an issue with caravan . Plumbers often have to cut or disconnect pipes . They are supposed to run a bridging wire between both pipes BEFORE cutting . If earth leakage is working ? It should trip ! Dont rely on it though !! Often its condensation on things like range hoods , elect frying pans , butter warmers in fridges etc . Reverse polarity was the issue where shock at tap instance . With MEN house systems .
I'm not sure what AS3000 says (and it's too early to look :) ) but in the UK it has been prohibited, for many years, to make the main installation earth via a water or gas pipe for exactly the sort of reasons mentioned.
Is plastic water pipe carbon impregnated to give some conduction? Probably not, it's too white.
The situation Iana mentions could arise but it's not very likely - I'd be more worried about being struck by lightning.
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"I beseech you in the bowels of Christ think it possible you may be mistaken"
Oliver Cromwell, 3rd August 1650 - in a letter to the General Assembly of the Kirk of Scotland
I'm not sure what AS3000 says (and it's too early to look :) ) but in the UK it has been prohibited, for many years, to make the main installation earth via a water or gas pipe for exactly the sort of reasons mentioned.
And for an extremely good reason. If the neutral path is interrupted between the house and the power pole (abraded away by trees, etc.) the household earth point can be at the full mains 240V with respect to another good earth.
When I experienced such a fault the household earth was the water pipe and the drains from the shower, kitchen sink, etc. were gal pipe and not electrically tied to each other. The net effect was that with, for example, the electric jug turned on there was about 160V between the kitchen sink and the tap. I first detected the fault when I got a slight tingle when turning the shower off.
I hasten to add that this was well before any leakage detection devices were mandated - circa 1975 or so.
In Australia, all mains power is on the M.E.N system[multiple earthed neutral}
Before the advent of nonconductive water pipes, it was standards practise to Earth the neutral via a neutral link to the mains water pipe.[definately not a gas supply pipe}
The neutral is also earthed at multiple points by the supply, at least[at every transformer supply point]
If you can get a copy of the latestAs3000 you will see that earth bonding is a far more intensive requirement now
Example being bonding:
concrete reinforcing to earth
Metal water containers.
Metal water pipes
Individual water taps, if they are connected by non-conductive piping,& the list goes on
Stringent conditions are set out for testing satisfactory [approved] earthing of the M.E.N in all situations
Depending on the soil conductivity , multi earth stakes bonded together or buried earth plates may be required.
G'day Ian,
These tales are perhaps a little off subject
1. A plumber in Townsville a few years ago got a "shock" when he cut a black pipe leading to the then Channel 9 (WIN) studios.
He thought it odd that no water came out - what he cut with his hacksaw was the fibre optic feed!!
No, I was not the plumber - just the technician at the Telstra end trying to find why they had no program! I don't know how much it cost him.
2. We had a fault that went on for 18 months on the Burketown to Burke & Wills Roadhouse radio link (60 channels - AWA RMA system). We thought it was a spurious as it happened in the warmer seasons between Doomadgee & Burketown. We changed numerous radio units but the fault kept returning. Having a warped sense of humour, I even sent the Mt Isa techs an Anniversary card to celebrate 12 months.
Yes, it was found - poor earthing of the tray that held the waveguides before they went up the tower!! What a drama it was!
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Warren
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If you don't get it done today, there's always tomorrow!
I'm not sure what AS3000 says (and it's too early to look :) ) but in the UK it has been prohibited, for many years, to make the main installation earth via a water or gas pipe for exactly the sort of reasons mentioned.
Is plastic water pipe carbon impregnated to give some conduction? Probably not, it's too white.
The situation Iana mentions could arise but it's not very likely - I'd be more worried about being struck by lightning.
Actually the latest Standard requires all taps, metal hand basins, Sinks, Bathtubs, slab reinforcing etc to be securely bonded to the main earthing point, which due to the now common use of poly piping which is nonconductive, must be by means of ground earthing..The effectiveness of that ground earth must be verified.& may require more than a single metal stake driven into the ground
Keep in mind tenges also an earth stake on every house . Taps and steel Is best bonded . So if theres any short ? There is no chance of being shocked between two . Sink and taps . Stainless shower footwell to taps etc .
