What do you mean "on the way"?
Either it is, or it isn't - there are no intermediate stages.
I really mustn't.
Ghostbusters.
TN-C-S Distrubution Fault Symptoms?
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Either it is, or it isn't - there are no intermediate stages.
It's not on the way to being TN-C-S, it is TN-C-S, because your installation is earthed to the incoming neutral. The fact that it's also connected to the sheath doesn't change that. TN-S means that the neutral and protective earth paths are completely separate all the way back to the transformer; if they share a conductor at any point, then it can't be TN-S, by definition.
That's why I also cautioned about the way in which one can find services which at the house might appear to be TN-S, and in fact which might still look exactly the way they did when they really were TN-S, but which due to changes in the local distribution network are no longer so.
There is bound to be some current flowing if you have any other connection to earth on your installation, and especially if both you and your neighbors still have solid metallic water services which are all solidly connected together.
Both the cable and the head are right to be original for that era.
For the wiring within you house? A local electrician.
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Thats my plan of action, i did quick check with a standard meter, but the resolution was .1 instead of 0.01 so i purchased a proper meter, but the readings showed the neutral loop resistance was higher than the line loop. The ring is switched off, and im planning to purchase some plugs so i can my probes, and test been each socket. I also want to map out the ring.
I tried to have a proper electrical contractor visit, but they seemed uninterested.
We also have all the old cables pre 1970 under the floor, and previous Economy7 installation that fed four electric storage heaters.
Thank you for your help.
Unless there is something extraordinarily weird about how the circuit has been installed, that would be due to a poor connection somewhere in the neutral loop. What sort of resistances, and what sort of difference between L and N, are you talking about?
Kind Regards, John
As I mentioned already, due to changes in the local distribution networks there are cases where the house might be earthed to the cable sheath but it is actually TN-C-S due to the fact that the sheath of the cable is no longer connected to the sheath of the distribution main but to the PEN of a newer cable. It might look just like TN-S at the intake position, but it isn't. This is where those neat little diagrams one often sees showing how to identify the arrangement can be misleading.
By how much? Certainly if there is a poor connection somewhere on the neutral then that could lead to unbalanced L & N currents in certain sections of cable, which would lead to higher field readings around those cables.
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I can see they are wired as TN-C-S, i never assumed it was still a TN-S just wondered if it was correct.
Could the house have metal pipes connecting with the neighbours?
If another house on the street was to have a neutral earth fault, would it pass through the water main. We are a semi-detached. Would the fault not pass through their earth?
Thanks
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O
kay so i was using a standard meter... I recorded .1 minus my leads for the live, and .4 for my neutral minus leads resistance. I now have received my Mit320 so ill be able to check it properly, as i expect the resolution is suspect.
People have added multiple spurs in the kitchen, a RCD spur to the garden shed.
kay so i was using a standard meter... I recorded .1 minus my leads for the live, and .4 for my neutral minus leads resistance. I now have received my Mit320 so ill be able to check it properly, as i expect the resolution is suspect.
People have added multiple spurs in the kitchen, a RCD spur to the garden shed.
Fair enough, but this 'speculative discussion' is all a bit moot given that we have seen the "PME" sticker on the OP's installation!
Kind Regards, John
I don't think there's any point in our attempting to comment until you have undertaken some 'proper' measurements with the higher-resolution meter.
Spurs will obviously not affect either the L or N loop resistances.
Kind Regards, John
How do you reach that conclusion from the fact that a device which is designed to detect conductors has actually detected some?
Sure - I was sidetracking a little to point out that all is sometimes not what those simplified guides may suggest, but in this case there's no doubt that it's now TN-C-S.
Seconded.
Yes. Or at least there's nothing obviously incorrect in your picture.
Certainly, especially given the era of the houses when that would have been pretty much the norm. There's a possibility that over the years a pipe has been replaced with plastic, or some other coupling which provides isolation has been introduced, which is why later editions of the Wiring Regs. no longer recognized a connection to a water pipe as an acceptable earth electrode. But there are still plenty of homes out there with solid metallic pipework between them.
The current will pass through any and all paths available to it in direct proportion to the resistances of those paths. Even with TN-S and water systems in two houses which are bonded to the respective cable sheaths but aren't metallically connected to each other there will be some current flow between them if they are close enough (a pair of semi-detached homes would be extremely likely to fall into that category). In that case the current would be quite small because the combined impedance would be significantly larger than that provided via the cable sheaths by several orders of magnitude.
But take two homes both TN-C-S and both with water systems correctly bonded to the supply PEN and which are metallically linked together themselves, then even under normal operating conditions some current will flow through the pipework of both homes, even if the main switch in one of them is turned off.
Didn't spot that possible interpretation!You're just trying to confuse him now.
TN Completely Separate.
Didn't spot that possible interpretation!TN Completely Separate.
It's always struck me a little odd to speak of a supply being TN-C-S. Isn't the 'supply', strictly speaking, actually TN-C, the "-S" bit being after the supply has got into the consumer's premises?Kind Regards, John
Include the tails to the meter in the 'supply'.
Indeed, that's obviously what we 'do' - but it still feels a little odd to me. That's why I tend to talk a bout a TN-C-S 'installation', rather than a TN-C-S 'supply'Include the tails to the meter in the 'supply'.
Kind Regards, John
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