Method to locate a short in a cable run.

[JohnW2]

.... I did doubt if it would work here due to 1.5K ohm impedance, ... and checked fault impedance if it had changed, it went right up to 10K ohms.

Indeed, these resistance-based methods are never going to work with high impedance faults, since the resistance of the cable (which one is relying upon to indicate where the fault is) is such a tiny proportion of the total resistance of the fault loop.

... my money is on his recent burst pipe leaking water in his concrete floor laden with water and CH pipes running all over, including to bathroom which lead water to this buried cable ...

I don't think that, alone, could explain a fault in the cable - PVC cables can retain their properties for years, if not 'for ever', totally submerged in water - and even if the cable were damaged to the extent that all conductors were exposed, I very much doubt that water could/would result in anything like enough current flowing to trip a 40A MCB.

... and who knows there may be a JB, concreted over through which water is making a contact between L & E and not between N & E.

That's slightly more likely, but, again, I suspect that even a JB full of water would not result in anything like enough current flowing to trip a 40A MCB.

Kind Regards, John[/QUOTE]

 

[Mikefromlondon]

Thanks John, admittedly I am also at loss, how this high resistance fault can suddenly conduct 40Amps, and trip things up, and even 30 + volts don't do much, like I said I will now take a little rest, i will let the owner decide which route he wants to take, I have clearly refused to reconnect it back due to high risks, risk of electrolysis, ( that is on assumption if water has ingressed the cable, though I equally agree with you that this cable seems very robust, but if it had been suffered any physical damage to its sheath and insulation, water and current coming together can risk in generation of explosive gasses, it is a risk too high, and so his only choice is either he runs a new surface mounted cable or dig his floors up. So far I have managed to determine that cable emerges to the Isolator from beneath his concrete floor. Runs through the plaster to about face height, and in the floor it runs for about 8 meters in length, it is a long extended kitchen/dining area.

I will keep you posted if he rips the tiles, I would like to know what happened and why, but if he chooses a new cable surface mount, we would never find out what failed that cable.

 

[JohnW2]

.... i will let the owner decide which route he wants to take... his only choice is either he runs a new surface mounted cable or dig his floors up.

If you have not already done so, don't forget to remind him that the reason for the RCD trips needs to be fully investigated. As has been said, whilst replacing the shower cable may well stop those RCD trips, and although it's not inconceivable (albeit requiring pretty esoteric explanations) that the shower cable fault alone may have been the cause, it is at least possible (probably much more likely) that there is also some other fault on one of the RCD-protected circuits that needs to be looked for and, if found, rectified.

Kind Regards, John

 

[bernardgreen]

A starter for ten about fault location on telephone cables.

www.econceptonline.com/PDF/Products/Cropico/Manuals/CF6_Handbook.pdf

 

[RF Lighting]

Thought you had a super duper magnetic tone far too good for electricians machine which would pin point the fault for you?

I really despair for your customer that you're still fannying about and trying to start a fire by driving currents through a resistance fault.

How many more days are you going to waste before you allow them to get an actual electrician who actually has the first clue how to find and repair faults?

 

[deadshort]

Billy from DIY SOS would find it faster !

DS

 

[bernardgreen]

Billy from DIY SOS would find it faster !

Of course he would, if he remenbered where he put it..........

 

[Mikefromlondon]

Thought you had a super duper magnetic tone far too good for electricians machine which would pin point the fault for you?

I really despair for your customer that you're still fannying about and trying to start a fire by driving currents through a resistance fault.

How many more days are you going to waste before you allow them to get an actual electrician who actually has the first clue how to find and repair faults?

Not in a rush at all now, owner has improvised a temporary solution to take shower using this from ebay that he attaches to his bathroom sink taps. http://www.ebay.co.uk/itm/PUSH-ON-D...596595?hash=item3f6a412fb3:g:BuYAAOSwgmJXzXMa
Firstly he is not my customer, I am not doing as a job, I have tons of important work to catch up with, this incident draws away my entire attention, my own job I bored to death with, and yes I have customers all over the world asking me where is their job and when can I deliver, I don't even reply to them. They can hell wait.

And yes I have given him best advise to dig out his floor, re-plumb all plumbing in a proper channel to run his pipes and electrics, it would mean removing tiles along a path and some across, that is a proper job, which unfortunately is beyond my scope, he will be getting a builder plumber or electrician possibly all in one to do it, more than likely where we live, it will be a pro from East Europe, his work will be supervised.
Unlike you, and those who thanked you for a completely worthless post, I am going to carry on fannying about until we have found the root cause of the problem, because not to do so is even more dangerous and more riskier as the problem could reoccur and cause untold damage and fire in future, so I don't do short cuts, we will take proper course of action, that is what is needed here, because there are other cables and pipes under his floor, having repaired a water leak under his floor, as we exposed through one tile, we took off, (we were lucky here because unlike electricity water started to seep out) and so as we saw the state of his other pipes that have not leaked yet, and this includes gas pipe, CH pipes, cold and hot water pipes, if you did not do fannying about and like most builders and tradespersons, they would have just get on with a job regardless of other implications, do their bit, take money and on to next job, leaving owners to face more crises in future. It is extremely hard to find proper tradespersons unfortunately, they all seem to have migrated. There are millions who claim to be professionals but they are less than that.

Just to reiterate, don't take my post as an attack on you or those who liked your post, my sense of humour is similar to yours. Oh and I do love fannying about to find why things work and what happens when they don't and how one can find faults and fix them, i love it!

 

[RF Lighting]

My post wasn't worthless. You just think it was because you don't agree with its contents. I'm expressing to you my genuine fear that you are going to kill your client with your incessant meddling.

I'm sure you'll refuse to listen to this advice as it's not what you want to hear, but it's the truth, and I won't stop telling you this until you do the right thing.

 

[sparkwright]

With all due respect Mike, I don't know why you waste your time buggering about with this.

 

[Mikefromlondon]

With all due respect Mike, I don't know why you waste your time buggering about with this.

My post wasn't worthless. You just think it was because you don't agree with its contents. I'm expressing to you my genuine fear that you are going to kill your client with your incessant meddling.

I'm sure you'll refuse to listen to this advice as it's not what you want to hear, but it's the truth, and I won't stop telling you this until you do the right thing.

This is the question you best ask that owner, whom I repeatedly pleaded with to get hold of a proper electrician, ( not that i can't do it) and my pitfall is that i get drawn to such like problems. He said he called an electrician, who said that he will need a new shower unit, and possibly a new cable, isolator switch, he quoted a price that left him stunned, so as the owner knows me well, he asked me to have a look if he really needs a new shower unit, and cable and isolator, apparently the electrician he called did not even try to reset his power at the MCB to see if it would retrip, he took the owners word that each time owner tried to reset, it would trip immediately, so the sparky assumed without carrying any tests that he needs a new shower unit based on how long have you had that shower there for and said its seen better days.

so I get drawn to such problems many who know me like seek my opinion. Perhaps I shall tell them to visit this site. You would only tell them what i told this owner to get a proper qualified electrician, but I like challenges, it keeps my brain ticking and I don't know why you are so paranoid and overly alarmed, you seem to think I am average joe blog who knows nothing other than how to change a light bulb, that would be an insult if someone asked me to change a light bulb.

(PS In my own house I don't even change a light bulb, I call an electrician to do that)
(sorry that was my bad humour)

 

[deadshort]

I don't know why you are so paranoid and overly alarmed,

Yes, that's the concern

DS

 

[Mikefromlondon]

No disrespect mate, but I am beginning to doubt of your own abilities now, so if you cannot work out that I am not a chippy, I worked with electrics for 50 years, and absolutely nothing has caught fire, so now it makes me think whether any of you should also be handling electrics. Should you not have taken some other safer trade like brick laying, plastering, or painting and decorating? we need some bus drivers in London.

Do you not know how dangerous Electrical stuff is, have you not seen those pavement explosions! Those that injure innocent people when the pavement slabs get thrown hundreds of feet into the air and who ran those cables there? especially when it rains!

for your amusement:

H&S makes me laugh, they are highly concerned for lives, and want to force electricity supply companies to prevent such incidents, that is as stupid as asking road drivers to cut down UK's car accident death rate from something like 3500 deaths a year to ZERO!
Or they will impose heavy fines, on those supply companies, thanks Mr H&S, you will be responsible for higher cost of electricity like it is very cheap already

Some accidents you cannot stop no matter what and how much you impose fines on companies, and I hope if you do fine companies, the money goes to victims and their families and not beef up your directors pockets.

 

[RF Lighting]

Because we are concerned that you are incompetent and may injure someone with your belligerence and genuine lack of knowledge we should stop working with electricity despite having the proper training, experience and competence to do so?

That seems like very flawed logic to me.

Perhaps you could explain your thinking to us?

 

[Mikefromlondon]

Because we are concerned that you are incompetent and may injure someone with your belligerence and genuine lack of knowledge we should stop working with electricity despite having the proper training, experience and competence to do so?

That seems like very flawed logic to me.

OK MR RF, thanks for your unduly concern, and please yourself, you seem to want to drag this thread into dispute.

If I may add, (with no disrespect) to you or anyone who tried to belittle my abilities, no one can judge others competence without first having inspected their work, and from behind a computer screen, I cannot judge you and your abilities, on here from my laptop screen.

I sat this long listening to Donald Trump and Hilary Clinton's debate, and couldn't believe how childish and stupidly they are accusing one another of not being competent enough to run world's most powerful Nation, and yet one of them will be in the White House soon, I dread to think and hope it is not Donald Trump, or the Third world war would be sooner than expected, perhaps I should nominate you as the most competent candidate for running for US Presidency, you might make a better politician than a good Electrician.

A good competent Electrician on here should have the ability to offer any advise to those seeking it irrespective of their ability to carry out electrical work, by not doing so you are making them take risks, and they can end up frying themselves,
Why do you think most people come here in the first place. Do they not know that they can get electrician from yellow pages. You are failing to address this problem people don't want professional to carry out some tasks they can do safely themselves, anyone who was not confident in doing so would not even come here for any advise, otherwise pointless having these Forums if you are only going to refer them to Professional electricians. So you definitely do not posess enough qualifications and experience to judge me and my abilities. But thanks for your concern, point taken, I will carry on as ever and as for the past 50 years. No fires, no shocks, no claims, and further more never ever needed to cover my work against any risks by having a PL Insurance because that is how much faith I have in my own ability. Much more than you could ever imagined or comprehend.
So I rest my case and I am no longer interested in carrying out this fruitless debate, because you know what , I always do what i want to do.