Power through water pipes - Dangerous?

I didn't know where to post it, so moderators feel free to relocate.

This morning the power in my house was doing funny things. Lights were going dim then bright again. Machines were turning on and off. Wireless phone base kept blinking its lights....etc...

My mum called Western Power. Whoever she talked to said to reset safety breakers if we have any, which she did. That didn't do anything, so they said they'd send someone over.

A little while later my mum reached for the tap on the kitchen sink and got zapped. Almost at the same time, my brother had the unlucky idea to take a shower and got zapped too when he reached for the tap.

So my mum called Western Power again, and told them they were getting electric shocks from the water taps. She demanded that they send someone right away.

The Western power dude showed up. He looked at our switchboard and said everything was fine there. He 'tested" the taps and confirmed that there current running through them. I don't know how he tested, my mum told me he had some electronic device.

Then he called more people from western power who brought a truck with a crane/ladder thing to reach power poles.

Now at my house, the power cable come off one of those power poles in the street, and connect to the top of a shorter pole in our garden, then disappears under ground.

The power guy said the problem was with the connection to the little pole. He 'cleaned' it and added extra isolation around the connection.

The guy told my mum:

-that it's common that current 'gets' into water pipes

-that it's the fault of salty breeze, due to living close to the sea (we're about 1.5km)

-that we were never under any danger because it was only a low voltage going through water pipes

Unfortunately I wasn't there. My mum isn't very clued on about electricity & power, so she didn't question what he said, and didn't ask many questions.

But when I heard this I thought it made no sense whatsoever, and I'm certain the western power guy must have been bullshitting. Of course he would say we were never under any danger, like he'd say anything else...

Any advice?

Reply to
Barry
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It sounds like you had a break in the power "return" line on the pole.

The salt air probably got at the joint on the pole and corroded it until it broke or made a bad connection- hence breaking the return path. When repairing it, the electrician added extra "isolation" to keep the salt air out, not to keep the electricity in.

If the house electrics had all been installed and set up properly and is in perfect working order, you were in next to no danger. It is worthwhile getting this checked once every few years, just to make sure that nothing else has corroded that could make you less safe. An electrician checking your "earth and bonding" should be able to do the tests needed in 30 minutes or less. That you actually got shocks off the taps could indicate that there is a problem as proper bonding should make this very unlikely.

If you are interested in the technical aspects of this, here is a simple explanation for the British systems:

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It can happen that a bonding wire going to a pipe gets broken - there will be no obvious effect until there is another fault. It is also possible that a clamp can become loose and I have seen one that was removed and then put back on a painted, rather than bare metal, pipe - which makes it useless. You may also have a ground "spike" - a copper-coated pointed steel rod hammered into the ground near the house, with a wire on. It is very common for that wire to become broken or the connection corroded - again, until there is another fault, there is nothing to show that this has happened.

Although it is easy to take the house wiring for granted - it is worth having it checked out now and again.

Reply to
Palindr☻me

Could this be one of those SWER (single wire earth return) systems?

To the original poster: How many wires from your power company are going into the transfomer nearest your house?

Beachcomber

Reply to
Beachcomber

It is not illegal in the US. In fact, it is mandatory.

Nowadays, you cannot rely on the water pipes to be the sole ground reference for the reasons stated. You have to drive a ground rod to be the ground reference point. But you still must bond the water piping to the ground for safety reasons.

The original poster seems to have two problems: An open return/neutral and an insufficient ground at the panel/service entrance. (I don't know the grounding requirements in the UK) Electricity was trying to flow from the hot through the lights/appliances to the return, and because the return to the service was open, it then flowed to the ground reference/water pipes, and because the ground was poor, through the poor guy's mum.

Reply to
Michael Moroney

That is how I saw it- but you put it better :)

Two minor points:

The OP is in Australia, not the UK. I would imagine that the code is similar to the UK, but am not sure about it. Equipotential bonding of all exposed metalwork does seem to make sense in any language though.

Secondly, the OP mentioned that the visiting electrician checked out the distribution panel. Now I can't see how he could have done this without checking the local earth - bearing in mind the fault that was notified. So it sounded like the local earth wasn't properly bonded to the water pipes..Hence the need to check out the bonding.

Reply to
Palindr☻me

Lzmain is posting the correct attitude. All other posters are strongly encouraged to comprehend what he has posted.

No matter what happens to AC electric, electricity must not exist in pipes. Furthermore connecting to pipes to dump electricity there is dangerous - and now illegal in many countries. A connection from breaker box to cold water pipe is only to remove electricity from those pipes. It is no longer valid as an earth ground connection.

A probably missing connection that may have prevented severe human safety threat is the earth ground rod. Every building must connect one wire of AC electric to earth ground. Every incoming electrical utility must also make a dedicated connection to this ground rod. With failure of one AC electric wire, the earth ground rod could have 'taken up the load' - protected human life.

In a parallel example, the home had no earth ground. When an AC neutral wire disconnected from utility transformer, then household electricity had to find other paths. It used the gas meter until a gasket finally failed. Fortunately no one was home when it exploded.

Find your building's earth ground connection. It should be a rather heavy copper wire from mains board to an earth ground rod (again, water pipes are no longer acceptable for this function). Wire should be about 4mm (or about 6 AWG). If earth ground does not exist, then definitely get an electrician to immediately upgrade or restore that all so essential earthing.

Getting shocked in the shower is never an acceptable failure

- anywhere. To happen, multiple failures must exist. They found and fixed > >> Sounds like you have two problems. The first is a poor ground return

Reply to
w_tom

I'll bet the answer *must* be two. The question you meant to ask is, "How many of the wires going into the transformer connect to overhead lines coming to the pole?"

(SWER still has two wires on the transformer, just that one leads to local ground instead of coming from the overhead)

daestrom

Reply to
daestrom

Should be 3, one ground and two phases.

Reply to
factoride

Electrical wiring and the Water pipes should never be connected for any reason. Someone could get killed.

Reply to
factoride

I agree the real problem was the open neutral/return lead, but before we decide the ground was "poor", let's consider Ohm's Law. It is very difficult to achieve, in most soil conditions, a ground connection with a low impedance. Usually a single ground rod will have an impedance higher than 10 Ohms. In fact, the US NEC clearly requires a second ground rod if the first measures in excess of 25 Ohms. Usually the installer just puts in two instead of measuring the first. In some soil conditions, the impedance will be well above 50 Ohms. It is easy to see how a large voltage can be developed if the grounding system is the only return conductor.

I had the same problem (open neutral between the distribution transformer and the house) a few years back and have a ground system that far exceeds the typical residence. My ground system has three 10 foot (3 meter) ground rods (well spaced) and a Ufer ground in a 20' by

40' in-ground pool. When I lost the neutral back to the distribution transfomer, the house neutral moved about 70 volts or so with a 10 amp unbalanced load. With the plumbing tied to the ground system (required by the NEC for other reasons), that would leave a bit of a voltage on the plumbing fixtures.

Where there are "good ground systems" they are extensive, with multiple rings, Ufer grounds, multiple rods and even counterpoises or "ground mats". These are usually found in power distribution substations, telephone exchanges and large industrial plants. The typical residence rarely has a ground system with only a few Ohms of impedance, as achieving that level is a bit impractical and/or uneconomical. With good neutral/return connections, the multiplicity of grounds in the distribution system and all the residences feed by that system works rather well.

Tell Mum not to touch the plumbing if the lights dim...

E. Tappert

Reply to
Eric Tappert

Has anybody considered a ground loop? I have found these from time to time. It's easy to correct and I haven't had any problems since.

Reply to
ssparling

If voltage exists relative to some mythical force, then this analysis is correct. But this is reality. There must be no voltage difference between bathtub and water spout even if earth ground voltage rises 10,000 volts. Problem eliminated because everything must connect to a single point earth ground AND everything must be interconnected. Furthermore if the 'hot' wire shorted to plumbing and bathtub was connected to earth, then circuit breaker should trip. Tripping circuit breakers is why we interconnect grounds - and then connect that interconnected network to earth ground. Soil conductivity would not cause a problem - and be apparent in light intensity variations.

To have a shock in the shower, multiple failures had to exist - no matter whether that soil resistance was 50 ohms or

0.25 ohms. To be shocked in a shower, a voltage difference had to exist. In a properly wired house (no matter what failure was out at the pole), that voltage difference could not exist. With the same house properly earthed means even less voltage difference could exist.

Multiple failures > I agree the real problem was the open neutral/return lead, but before

Reply to
w_tom

Ground loops would exist if the wiring was in violation of what I had posted previously (Monday). Ground loops should not be a problem. Again, to have someone shocked in the shower, then multiple failures must exist. Electricity in a shower or bath is that dangerous that we have long since made these grounding requirements AND upgraded them over the decades.

Electric shock > Has anybody considered a ground loop? I have found these from

Reply to
w_tom

Tom. I had a similar situation in this house when I moved in. The electric service was grounded with a rod and a bad connection occurred there. The pipes were bonded but a plastic service to the house prevented them from being grounded. There was enough voltage gradient between the neutral and ground that you would get a mild shock if you were barefooted on the terazzo floor and touched a water pipe. Improving my grounding electrode system fixed the problem.

Reply to
Greg

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