On Mon, 02 Jul 2018 22:43:32 +0100, trader_4 wro= te:
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Do you seriously think that just because some of the lightning can jump = to =
the earthed side that none goes into the house? It's precisely the same= =
as having a 3kW heater and a 40W lightbulb on the same circuit. The =
heater doesn't take all the current, the lightbulb still works.
Looking for doesn't mean travelling.
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That can be done with an isolated supply just as easily.
Please don't misquote me. I said from the beginning that the vast majority of the lightning energy on a system with an earthed conductor never gets into the house. I never said *none* of it gets into the house. Less is much preferred.
It's precisely the same
It's kind of like that. With an earthed service conductor it's like having the 3KWs of power dissipated into the ground rods at each end of the service conductor and it going into the earth, with the mere 40W of power going into the house. You have orders of magnitude more energy safely diverted to earth as compared to what enters the house. Precisely the case I made from the beginning.
With your unearthed, isolated system idea, there is no earthing at the ends of the service conductor, so all the lightning energy now has to find a way to earth, via whatever means are available. The path into the house has an impedance path many orders of magnitude higher than an earthed conductor. How would it get to earth via entering the house, instead of going into the ground rods at either end of an earthed conductor? It would go into the house and then what? Arc over to a water pipe? Arc to a sewer pipe? Arc to a metal conduit and then arc from that to something else, like you standing at a sink washing your hands? If it's a metal building, arc across to the building frame? Go through your TV set blowing it up and out the cable system connection which is earthed? All of those paths present orders of magnitude more impedance than the direct earthed connections on the service conductor. And all of them present the opportunity to set the house on fire as the lightning finds whatever unpredictable paths to earth it can.
The lightning energy that strikes a service cable has to go somewhere. With an earthed conductor, there is a low impedance path to earth, on both ends of the service conductor. With your system, the lightning energy will travel to earth and since you don't have your system earthed, it will seek unpredictable paths, many of which can burn the house down, destroy eqpt, or kill people.
But as I said before, if you're so smart and know what you're doing and you can do as you please over in the UK because it's your own house and no codes apply, then just go ahead and remove the earthing. Why pester us?
No it can't because the current system earths both ends of the service conductor via simple ground rods, no other surge protection is necessarily needed, though it will add additional protection. Your isolated system, if you want to protect the transformer side, you'd have to add a surge protector there, instead of simply earthing the neutral. It's another component, another failure point, another maintenance item. At the customer side, presumably there would be no ground rod because you said you wanted an ungrounded system, so why would there be a ground rod to begin with, or a panel with a ground bus, etc? So I don't see how it's so simple to add a surge protector to a system with no earthing and where no earthing is required. At the very least it requires a surge protector where one was not needed before and a ground rod and a way to connect it all. It's starting to sound more complicated than what we have now. Imagine that?
And additionally as has been pointed out by many of us, modern devices that save lives and greatly improve safety require grounding, ie GFCI,RCD. With them a fault to a metal case, a short to a pipe, etc will cause a trip from just a few MA of current, well below the lethal threshold. With your ungrounded appliances and system, the same fault leaves the case energized waiting for any possible connection to a fault on the other side of the system, be that through water pipe, metal ducts, metal building components, or you.
In article , Jimmy Wilkinson Knife scribeth thus
You still don't get it do you?. Yes you can but thats stupid as any sub wired of that presumed balanced floating transformer can upset the floating only one has to have an earth leakage fault and its all to pot..
Why don't you read up on power theory?..
You'd soon be into the leccy power co complaining of a loss of supply!..
At 230 volts at a mile or so?..
That's true. The more homes, buildings, and things on the isolated side, the more easy it would be for something to compromise the isolation. And a single transformer could and typically does multiple loads, eg supply your house, the neighbors house with faulty underground wiring going to outdoor lights, a pool, street lights, etc. Good luck not having some ground fault somewhere.
Normally 11KV or more.
Better than it trying to return through ground.
Is that a problem?
Which, if it did happen, would still not be as bad as the thing properly grounded as it is now. With an isolated supply you require two faults quite close to each other.
Are you really this dense or do you just pretend? Under the current method if you have a fault to a metal case, conduit, anything that's grounded, if it's a hard short, it trips the breaker. If it's a partial short, the case is still not raised much above earth, the water pipes, the metal in the building.
In your isolated proposal, the case is immediately energized and no breaker will trip. It remains energized. If it comes in contact with any other metal, eg via gas pipe, water pipe, being in contact with the building, it now has a path to earth too. So someone in the house next door has the opposite fault and now there is a lethal path between a person there who touches the appliance and a sink faucet, etc.
And you continue to ignore the huge problem with isolation, which is that you no longer have one side of the service earthed to easily take surges, eg lightning strikes to earth before they get inside the building. With your proposal an overhead service is like an aerial, almost like Ben Franklin's kite with a metal string, waiting for a lightning strike that now has an unpredictable path to earth, including through the house and it's contents.
In article , Josh Black scribeth thus
Is that used in the UK anywhere at 230?. I Believe theres a 900 kV DC supply around somewhere doing that...
Wrong, a shaver socket output is two ends of the transformer secondary, nothing is earthed.
Just how short are your appliance cords?
Never had that happen to me. I've known it happen to one friend, it just ended up open circuit.
It doesn't. If someone plugs in two 3kW appliances (and most people think that's ok in a double socket), it soon melts and can cause a fire.
If it did it would only be as dangerous as the already earthed system.
It's bullshit, I've seen two 3kW appliances running off a double socket which melted and almost caused a fire. Luckily the flammable stuff (a pile of paperwork) was not quite close enough to the socket.
Short enough so that if the power point is further from the bath than can be splashed if the kids start splashing each other in the bath, it cant reach from there.
Because you don't have a hot water heater, stupid.
The technical term for that is 'pathetically inadequate sample'
Bullshit.
Nope, the GPO just chars.
The problem is that when everyone knows it's a floating system so they can touch anything they like, the first time it ends up being earthed that way, people start getting electrocuted.
Given decent quality plugs and sockets that shouldn't happen. Does anyone really run Six kW continuously off a double outlet anyway?...
I've seen less than that load (continuous) melt the insulation on the feed to a socket. That was because the screws weren't tight. Nearly set fire to a rather nice listed barn.
Your system has so few volts, nobody cares.
So the washer and tumble drier are pulling 6 kW all the time then?..
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