Earths can be dangerous

[Mr Pounder Esquire]

Prick.

[Mr Pounder Esquire]

Prick.

[Jimmy Wilkinson Knife]

Can but usually doesn't. Why do you deal with worst case scenarios? Yet in other areas, like loading of double sockets, in the UK they assume that probably nobody will exceed 20A on a double 13A socket, so the socket is rated at 20A, not 26A which would make more sense.

[tony sayer]

This - is the fallibility of your argument.

You have a balanced isolated supply but in the real world electrical equipment can and does develop faults. A cooker can develop a leakage in an element to the framework of the cooker an immersion heater can develop a leak from the heating element to the metal case of the unit thence to the metal hot water tank. A washing machine can do the same with its heating element and it can also leak water into the motor thus in doing so the assumed balanced isolated supply is no more, you are back unknowingly to the current setup with the live and neutral system.

Or an unknown variant of the same, consider that if one unit were to leak to earth on one side of the supply one on the other how would you detect the current flowing away to waste there?

However if you have the established system you know that one side is in earthed and you can prevent all manner of accidental electrocution with a rather simple device a Residual Current Breaker this one device has done more to prevent electrocution than any other:)

To do this isolated supply would mean rewiring the UK. New transformers would be needed and the space to put them. Do bear in mind that some residential accommodation like flats might not have the space if you put them outside then you'd be doing a lot of road digging and overhead wiring for what real benefit?.

Let alone the removing of all the metal water pipes in the country. Also do bear in mind that not everyone is your electrically resistive self people do have wet bodies in showers, children may not be quite so hardy either.

Think through the wider real world issues then you'll realise there isn't an argument for what you propose.!

[Jimmy Wilkinson Knife]

No. If my washing machine was fed from an isolated supply, and developed a leak to it's chassis, there would be one leg of an isolated transformer output on the chassis, with nowhere to go if I touched it, so completely safe.

Now you're considering two broken appliances, you're really pessimistic.

We used to manage with just fuses.

Why would the isolated transformers be larger?

Just don't put them in in new installations. I'm not asking for everyone to suddenly become isolated by next week.

Bullshit. Everyone is pretty much the same, save for a few with dodgy tickers.

[tony sayer]

Yes except that there are likely to be other appliances that can develop leakage such as cookers, immersion heaters , kettles , electric irons water heaters..

Yes maybe but it can and does happen over time but the danger is you wouldn't know its happened with a floating supply. With a live neutral system it does come to notice rather quickly and the fault is noted and rectified..

Yes we did manage but then again the human body currents are much less then what a fuse can sort out..

They'd be many many more of them!. The current 3 phase distribution system can and does supply many properties with a floating supply to each property may more individual transformers are needed. Who is going to pay and to what real benefit?.

And thats -- the reason why your not in charge of the electricity supply in the country!...

[trader_4]

You're conflating two different things, bonding the eqpt grounds to one side of the supply and an earth ground. You could use JWS's isolated supply idea, where it's not tied to earth ground, but you still tie one side of the supply to the eqpt ground at the panel. Then you'd be in the same situation as we are now with a fault to the metal cabinet. If the fault is on the bonded side, the cabinet is not energized. If it's on the other side, it trips the breaker.

That's for sure and we had plenty of people electrocuted and dead. A teacher at my high school years ago died using a shop vacuum to suck water out of a pool while standing in it. Today that circuit would be protected by a GFCI (RCD over there?), and he'd be alive.

I agree it makes no sense to change, but theoretically there is no reason that several homes could not be on one shared transformer that is not tied to earth ground just as easily as they are one that is tied to earth ground. The big disadvantage which I addressed much earlier is that without the service being tied to earth ground, there is no easy, direct path for abnormal surges to take. With the existing service, if lightning strikes the transformer, the pole, the service going into the house, the vast majority of the energy flows directly to earth ground. With no earth ground, now what?

I agree, he should not be in charge of anything. Every time he disparages building and safety codes, I immediately think of that towering inferno you had over there recently, where I believe codes for what was allowed for the building covering were not followed. Or even if they were followed, the codes then would have been inadequate and a good example of why we need codes to stop people from building unsafe structures that wind up killing everybody.

[Jimmy Wilkinson Knife]

Why should we protect someone doing something that monumentally stupid?

Indeed, just remove the tie, no extra expense.

You worry too much.

And how many buildings didn't meet that end? You're a typical newspaper reader, 1 in 50,000 buildings catches fire and you think they're all dangerous.

[Jimmy Wilkinson Knife]

Very unlikely you have two problems at once. I've never actually encountered a single device with a leak to the chassis.

You'd still feel a tingle when you touched it.

And yet we're all alive.

Why does removing the link from one leg to earth, mean more transformers?

What's the reason? Because I don't think the whole world should tread on eggshells for the few that are both stupid and have dodgy hearts?

[Terry Casey]

Do you think anybody is going to wade through all of the crap to find out if you ever write anything worth reading?

[Jimmy Wilkinson Knife]

Clearly whoever you're replying to (as you didn't bother to quote their name), and the other person or people they were talking to didn't mind. You're on your own mate.

[tony sayer]

That's what the RCD will cope with..

Some are - some are not;(..

Suggest you read up on power distribution in the UK..

>

[Jimmy Wilkinson Knife]

It doesn't need to. No path to earth, not enough to kill you.

Survival of the fittest. I've had many shocks through me at 240V and just jumped. For example the last one I had, I was mowing the lawn and the cable of the mower was damaged, I grabbed it and touched the bare live wire while my bare feet were on the lawn. I shouted abusive words and let go. No harm done except my religious neighbour objected to my blasphemy.

So you don't know then, thought so.

My local substation has three phases and ground. Just disconnect that ground from ground, job done. Instead of me getting ground and 240V, I'd get a floating 240V pair, neither of which would hurt me if I touched it and the ground.

[Rod Speed]

That wont work, because any house supplied from that substation which has a faulty heating element in a water heater or oven or washing machine will in fact be earthing the phase it uses.

What would work is the way your builders supplys work, a separate transformer at each house, but that's obviously going to be a lot more expensive than the current approach.

The problem is with all those elements that fail in all the houses supplied from that substation actually earthing that phase.

[Max Demian]

I can see that the only way to silence you would be for you to try it out.

[trader_4]

It will only be earthing the isolated secondary from the final transformer that serves that house or small group of houses. That is very different than deliberately earthing all the secondaries.

There is no reason each house would have to have a separate transformer. There is no necessity to earth anything to allow one transformer to serve several homes as is done right now. The system right now does not rely on earthing in order to be able to serve more than one house.

They are not earthing the phase from the "substation". They would be forgoing earthing from the secondary side of the final transformer serving a house or group of houses.

It's still a bad idea, for a variety of reasons, but the above are not on the list.

[Jimmy Wilkinson Knife]

I know what a floating voltage is, clearly you don't.

[Rod Speed]

It wouldn't silence him because that is in fact one common way of safely operating defective devices, with an isolation transformer that allows you to no longer care if the case is live etc.

[Max Demian]

That might be all right with a single appliance, and, in fact, is what shaver points do. It's a different matter with the general supply to a house as there are lots of appliances that might be (partially) earthing one side or the other of the supply.

[Jimmy Wilkinson Knife]

Don't they do that just for changing the voltage to make them international?

I removed the transformer in mine so I could connect bigger appliances to it with an adapter.

You're a right pessimist if you assume TWO faults.