Armoured Cable Question.

[UNG]

I also have a beer in hand. You have helped me a lot. I hope I can now ask reasonably intelligent questions about this armoured cable and the alleged reading. What if I find it is not true! I am trying to give this man the benefit of my doubts but I am struggling.

Just to try and get some perspective on this prior to the testing was this cable in service and operating normally if it was with the resistance figure quoted I'm thinking a decimal point may have been dropped or the MFT was setup incorrectly and gave a red cross in the display so was considered a fail by the tester
Approximately how long is this armoured cable and what is the overall diameter so we can try and identify the conductor size

 

[littlespark]

The details of the cable are sometimes moulded into the black plastic covering… ie 2c25

 

[James Farrell]

Just to try and get some perspective on this prior to the testing was this cable in service and operating normally if it was with the resistance figure quoted I'm thinking a decimal point may have been dropped or the MFT was setup incorrectly and gave a red cross in the display so was considered a fail by the tester
Approximately how long is this armoured cable and what is the overall diameter so we can try and identify the conductor size

I have calipers and will measure in the morning. I would guess about 15 metres end to end but I can tell you tomorrow. It has been working fine but since it was condemned it has been turned off. I will upload some photos tomorrow which may help.

 

[James Farrell]

Cable may not need replacing just wait for the second electrician. I suspect the reading they have stated is a high earth fault loop impedance (Zs) due to a breakdown of conductor continuity, this is an assumption though. If this is the case it may be possible to correct this.

This is very helpful. I wonder if I can show these postings to my new Electrician. He is NICEIC Registered and he has been highly recommended. He is booked up in the early term but he will assist. The generous responses have been amazing and I am very grateful. I hope this will have a good and safe outcome.

 

[westward10]

If he knows his stuff he will fathom it out without us but we would like to know the outcome.

 

[UNG]

I have calipers and will measure in the morning. I would guess about 15 metres end to end but I can tell you tomorrow. It has been working fine but since it was condemned it has been turned off. I will upload some photos tomorrow which may help.

I think this would suggest that the guy who condemned it got it wrong somewhere

 

[westward10]

I think this would suggest that the guy who condemned it got it wrong somewhere

I would put money they are referring to Zs.

 

[UNG]

I would put money they are referring to Zs.

With a decimal point missing in the figure quoted is my thinking

 

[James Farrell]

If he knows his stuff he will fathom it out without us but we would like to know the outcome.

Good Morning Westward 10 - I wish to thank you and others you so helpfully gave up their time yesterday to respond. I will measure the armoured cable length this morning and try to identify the cable at the Oak Building Consumer end of the run (with it switched off having been made aware of the danger). I will take digital pictures I hope I can post. Of course I will advise on the outcome.

 

[James Farrell]

With a decimal point missing in the figure quoted is my thinking

This is a duplicated posting by me this morning Ung: Good Morning - It is a far more serious issue this morning as I have examined the Consumer Unit this morning and located the main armoured cable. It is more like 20 metres end to end. I discovered by lying down and look up with a torch that there is an earth cable no more than 2 inches in length cut off and in mid air. The live and neutral go to the main fuse. No wonder he advised of a risk of death. The obvious question this poses is if this earth cable is earthed both at this end and the other end (it may be) then will the Test Reading give a safe result? The Electrician recommended running a new armoured cable end to end. This would have been a huge high cost job but if this ultimately must be done to make it safe this is what we will instruct. I have not checked the other end and I stress again I am not an electrician but a 74 year old very worried home owner.

It is extremely hard to read the writing on the cable as the Power is off and I could only use a torch. It is 12 mm cable and it may read as follows:

FIECTRIP CABLE?
600/1000V
Coraka or similar?

Does this help?

 

[westward10]

You really need the opinion of the second electrician as this may be possible to rectify.

 

[James Farrell]

Here is a picture of the Consumer Unit in the outbuilding. The condemned armoured cable is on the right. The live and neutral go to the 63A Fuse pictured left. The top of the cable cannot be seen but to my horror I saw a short length of earth wire (no more than 2 inches) not clamped in an Earth Terminal but hanging loose in mid air. Could this explain the high ohm reading reported. No other explanation was offered. I was not advised of this unclamped earth wire. There are many empty terminals and the earth cable could easily be clamped. As I am not an electrician I am taking no risks. I hope this assists the many kind electricians who have tried to help me. I am waiting for a visit from a recommended NICEIC Electrician.

 

[James]

We would love to hear the outcome of this,
I am wondering if the outbuilding is on its own TT supply and has its own earth rod.
I am further thinking that the 371 ohms is because the rod is no longer providing a good earth.

A good electrician should be able to explain what the issue is and come up with a solution to fix it.
I suspect that the distribution board in the picture may well need replacing.
the bus bar at the bottom looks heavily corroded and the 63A RCD on the left looks like it has heat damage on its upper right hand side.

 

[westward10]

A rod (TT) is a possible with that rather large conductor at the earth bar.

 

[brianmoooore]

the bus bar at the bottom looks heavily corroded

Looks like it's tinned to me. That would be a first.
No SWA gland or earth connection to the SWA, and a big earth cable that's either a bond (to what?) or to a rod. Has to be TT, surely?

 

[Rockingit]

View attachment 102718

I also suspect a TT / Divorced earth situation, however I'm finding this picture confusing because... Red/Blue conductors would normally indicate an old cols 3c cable yet I see no yellow, and we've two brown lives in the box (B10 and B16) yet only one blue neutral??? We also seem to have three circuit cpc's into the bus bar for four circuit??

 

[James Farrell]

We would love to hear the outcome of this,
I am wondering if the outbuilding is on its own TT supply and has its own earth rod.
I am further thinking that the 371 ohms is because the rod is no longer providing a good earth.

A good electrician should be able to explain what the issue is and come up with a solution to fix it.
I suspect that the distribution board in the picture may well need replacing.
the bus bar at the bottom looks heavily corroded and the 63A RCD on the left looks like it has heat damage on its upper right hand side.

The Consumer Unit is not old and looks like new and there is no corrosion and no heat damage. I really appreciate the kind responses I am getting and possibly only from experienced electricians. I am an elderly home owner and not an electrician and I am trying to understand but this is difficult as I do not follow much of the technical advice. I was told the armoured cable was non compliant and the only reason given was the alleged reading of 371 ohms which means nothing to me. I was told it was dangerous so the reply is turned off. By visual examination I discovered, to my horror, that the earth wire coming from the armoured cable is cut short and in mid air. It is not connected to any one of many earth terminals. I simply wondered if the earth wire is connected if this was likely to produce a safe reading? The electrician was recommending the replacement of the armoured cable. This would be a huge job over a distance of about 20 metres running underground below a concrete floor and a concrete slab adjacent to the outbuilding. It is an awkward sloping site and the cost will be very high but if it is true that it must be replaced to make it safe this is what we will do. If wiring to cut earth cable into an earth terminal makes it safe this will take minutes and minimal cost. I have an NICEIC Registered Electrician visiting in the next week. I will advise on the outcome.

 

[James Farrell]

If he knows his stuff he will fathom it out without us but we would like to know the outcome.

Does this help? The top of the armoured cable is behind the top plate so cannot be seen. The arth cable coming from the armoured cable is cut and can be seen in this picture. As I have stressed several times I am not an Electrician so I struggle with the technical responses so kindly given. I simply wonder if this is why the Electrician said the armoured cable was not compliant and should be replaced which would be at huge cost. I am hoping that once this earth cable is secured in one of many free earth clamps it will then be safe and a safe reading will be produced? Unfortunately the reported unsafe reading of 371 ohms means nothing to me. Questions have been raised about the condition of the consumer unit. It is metal clad and modern and to the untrained eye looks in new condition with no heat marks on any of the fuses as suggested. I hope this clarifies and helps. The good news is that are NICEIC Registered Electrician hopes to visit within a week and I can then report the outcome. Fingers crossed.

 

[UNG]

Do you have a picture of the cable a bit further up and / or a bit of a wider angle so we can see a bit more of how the armoured is installed

 

[James Farrell]

Good Morning Ung - There is no power on in the building following the advice the armoured cable is non-compliant and the serious risks. I used a torch last time which was not ideal. I may be able to use a light on an extension lead from our house and if I can then I ought to be able to get a better picture. I hope to send one later. Thank you for your continuing interest.