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Topic Title: Earth path
Topic Summary: shower fault
Created On: 03 October 2010 11:54 AM
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 06 October 2010 07:41 AM
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Avatar for ebee.
ebee

Posts: 5672
Joined: 02 December 2004

As a guide , sorry not as a guide - I'm not suggesting figures here for that resistor.

Merely an observation

24K ohm resistor would pass 10mA at 240V (2.4W)
or 17.29mA at 415V (7.18W)
and
48K ohm gives 5mA (1.2W) at 240V
or 8.65mA (3.59W) at 415V

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 06 October 2010 09:27 AM
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potential

Posts: 1257
Joined: 01 February 2007

As a passing comment, I didn't notice much difference between AVOs "ease of service" (was there ever such a thing in those days?) however there were many different internal designs just for the model 8.
A common, annoying and disasterous fault when making an AVO repair was not placing a "keeper" across the magnet when it was removed for some reason.

I learnt all about care of magnets from my Horby Dublo days.
 06 October 2010 07:24 PM
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Zs

Posts: 2849
Joined: 20 July 2006

An update as promised. I'm afraid I knew about this yesterday but didn't want to log on.

The facts:

supply authority attended. They told the customer that there was an earth connection on their cable but that it was barely connected to it and was very worn out. As such they said it was not dangerous and they are going back in a week to improve it.

The other electrician attended and has given them a quote for changing them to a 17th Edition set up, and for adding bonding. He replaced an outside light for them and is going back in a week or two to do the fuse boards and bonding. (Let's not go there eh?).

I took a call from first the supply guys and then the phone was handed to the other electrician.

The supply guy wanted me to know that I have wasted their time and that, I should know that there is an earth on their cable. That this is not an emergency. I asked him if he could confirm for me that it is a TNS. He said what? and then said it was an earth to cable sheath or something.

The other electrician wanted me to know much the same and that I have scared his customer, but thank you for the business.

Alan, how far down a TNS incoming cable from the main fuses can the connection for the earth be? I told you that I could see the old lump and that there was nothing coming from it. I couldn't get very far down the cable below that lump, about 15 inches or so before it disappeared into the ground. There was nothing on it.

I also haven't offered you a Ze reading because there was absolutely nothing to attach a croc to for a pure Ze. I use a three lead tester and long may it remain so. The only thing I can offer you is a Zs from a close by socket circuit (so I doubt much R1 + R2 to speak of ) of 4.5 ohms. The words disconnection and time come to mind.

Anyway, there it is. Feeling small, incompetent and as though my incompetence has been used to jack-up somebody else's competence. It doesn't happen very often but sometimes I get treated like a hobby electrician who's Daddy or rich husband paid for a five day course and bought a shiny little van for, and this was such a conversation. I feel rotten.

And shame on me I disconnected that shower last week.

Off to, oh I dunno, howl at the moon or something

Zs
 06 October 2010 07:41 PM
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OMS

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For sure there is something very wrong on that incoming supply cable - your Zs at the nearest socket proves that

If you want Ze put the croc clip on the lead sheath is my advice (carefully)

No comments on the faulty shower circuit from either party I note particularly as you managed to light a drummond between the taps and the CPC.

So - chin up, keep thinking Jimmy Choo, get the "glug" out and find an appropriate piccie for the site - RnR has had about forty so your lagging behind a bit madam

Regards

OMS

-------------------------
Failure is always an option
 06 October 2010 08:11 PM
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slittle

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Zs,

If it helps, at a meeting this morning, a very nice man from EDF (who's land I think you're in) confirmed that all of their old eastern network was PME capable and if as electricians we found a service with a Ze > 0.8 (tns) 0.35 (tncs) we should report it to them.

If you want names etc, pm me


Stu
 06 October 2010 08:44 PM
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sparkingchip

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No doubt I have told this story before, I was working at a house with a raised fishpond with a brick wall around it and a plastic liner inside. The lady of the house was sat on the wall feeding the fish and a big Koi came to take a piece of food out of her hand, they both jumped back and she said I've just had a electric shock, my comment was that the fish did as well.

So her husband announced theres nothing wrong with the pond and stuck his hand in to prove the three of us wrong (his wife, me and the fish).

A simple bit of testing proved the pond was live, despite what the husband said.

Don't let others try to get you down after they have just given the installation a cursory glance and told the husband what he wanted to hear.

Andy
 06 October 2010 08:57 PM
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Avatar for ebee.
ebee

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Well ZS,
going off what you've said,
that supply just don't sound right to me either.

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 06 October 2010 09:41 PM
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MrOther

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T5-1000.

I was never brought up on a multimeter, and there's something about the look of 'em that never sat with me, I do like my Flukey meter (excluse the pun, though was intended.)
 07 October 2010 10:03 PM
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Zs

Posts: 2849
Joined: 20 July 2006

Your'e very sweet and I thank you. Who knows what the real story was from monday. i'd love to know but I won't push it. I stuck to broadband, sonos and telephones today...cor, telephones are easy and boring aren't they?

A N Other electrician called today and politely offered me a 50% share of a rewire reasonably local. Now this is bizarre and the way I see it one of three reasons for that call apply: 1) guilt 2) His registration has expired or is about to 3) He fancies his chances ( That'll be a no then).

I love the fish story and I will be using that as an illustration.

Thank you.

Zs
 08 October 2010 05:50 AM
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ebee

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4) He has realised that you know your amp from your elbow

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 09 October 2010 01:09 AM
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Yooj

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Zs, I would not let this lie if it were me...I would try to get back in to see the installation again, and see if you can do a Ze as OMS said via the lead sheath, and if not, then several Zs checks of various circuits to see if all are high. Also re-test the pipework, in the bathroom and the kitchen, using Mr Capon's screwdriver in the flower-bed. This would then give you a reasonable idea if things are well or not.

I am suggesting this for two reasons, firstly your sanity, because there is nothing worse than a niggling doubt on your competence, so don't take it lying down.

Secondly, if there is a real risk to life, then god forbid if something did happen to the householder.

Even if you say to the householder that you are willing to do the testing gratis, because if you are proved right, and it is a dangerous situation, then EDF and the other spark are going to look like mugs, the householder will be grateful, and you never know, you might get the work after all..

Yooj
 12 October 2010 09:54 PM
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Zs

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Joined: 20 July 2006

Well Yooj, you, and John Peckham, who sent me an email about this are as one.

I got a letter this morning, from the husband.

'Thanks for your very informative letter.
A guy from EDF has been round to do a test and said that it is just, and only just, within acceptable limits, but that someone will be round soon to change the fuse box which EDF is responsible for. He explained that the present situation means that trip switches are slower to respond. However, we shall take your advice and get the one in the bathroom changed.

He seemed to imply that a private electrician could sort out the water and gas earthing (though I may have misunderstood). So do we need to contact the water suppliers or gas suppliers?

Meantime, your cheque for £50 is enclosed and we thank you for your quick response.

Best regards.'

So I got beaten up but I'm happy with that. Some of what I said made an impression and by now they will be fine.

Zs
 15 November 2010 10:05 PM
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Zs

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Joined: 20 July 2006

I thought I'd give you an update on what the supply authority did to this one. I'm due in next week for a full PIR and the supply men were there last week. So I called by.

It has a shiny new TNS on the incoming cable, and new main fuse.

I'm really curious as to the previous 'borderline' comments.

i'll try to get you a photo.

Zs
IET » Wiring and the regulations » Earth path

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