I have just carried out an I&T on a barn conversion in Stu Little's territory. Last month I did a neighboring barn conversion and was told about a fire on the property I did yesterday. The story I was told last month just did not add up from information provided to the owner of the properties by her builder and electrician.

Having closely questioned the builder this morning who I suspected was spinning a line to cover up something I got a key piece of information.

The fire started outside on the timber cladding where a boiler supply oil pipe enters the building. The occupiers smelled smoke and put out the fire with a bucket of water. The FB attended and whilst looking at the fire having turned off the front end 30mA RCd protecting the whole installation the builder knocked the charred remains of a flexible pipe there was a spark and the fire started again. The FB put this 2nd fire out.

The FB turned off the supply to the neighboring property.


What I was not told was for 2 weeks the supply was off the people moved out and a series of electricians attended site and were measuring strange voltages in both properties. They then called in UKPN who went up the pole and cut back the trees, that continually bashed the overheads, and re terminated a cable. After that all was well.

The supply is overhead from a pole transformer. PME earthing with PME label on head. No gas, plastic water pipes but a common oil pipe line in copper underground common to all 3 properties. BS951 clamp on oil pipe line with 10mm bond to consumer unit.

I have a nice photo if anyone is interested.

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John Peckham

http://www.astutetechnicalservices.co.uk/

Overhead PME flight - and by the sounds of it perhaps a "shortage" of terminal DNO electrodes depending on how they have viewed the requirement for a minimum of two and thier locations under ESQCR

It was bound to happen I guess John

Regards

OMS

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Failure is always an option

Was it a 3-phase transformer?

Just thinking that it might be a combination of problems...

o Lost N resulting in >>230V on some properties
o Oil pipe acting as parallel N between properties (i.e. N current flowing out of furthest property, along oil pipe and back into to CNE at a properly nearer the transformer) - not necessarily to earth as such. (fire starts at the property with the loosest clamp)
o Poor CNE joint between properties results in oil pipe taking even more current.

I guess we should be grateful it wasn't a gas pipe with soft soldered joints....

- Andy.

I blame the crimped joints.
Twice our overheads have been 'upgraded' in the 30+ years we have been here and both times within days a shower of sparks told their own story.
Last time I even stood outside and told the linesman to make sure the joint was OK - less than a week later the aluminium centre core failed (11pm in the dark naturally, just dropped the bit on the road which I picked up next morning)

Sub-contractors, doncha just love em?

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Norman

I would be interested in a photo please John.

Im working in a water site at the moment that is supplied by a transformer on a pole. The earth electrode for the transformer has been requisitioned by speculating metal dealers that travel around a lot.

We dont seem to be getting any strange voltages or issues on this site because of it, but im guessing that the fact that there is a lot of earthed piepwork has something to do with this.

Ive refused to energise a part of the installation i have wired until the DNO return to reconnect the transformer to earth.

Was this the correct thing to do?

At the moment, i feel that the installation is safe because of the main equipotential bonding in place, however contractors and water company employees often carry out ad-hoc works that could include the disconnection of the bonding conductors. My experience tells me that these are often not reapplied, and if they are, they dont bother trying to find proper contact with the metal, they just shove a banjo on a painted bolt, onto a painted flange!

John F

''requisitioned by speculating metal dealers that travel around a lot. ''

Love it!

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Lack of planning on your part doesn't make it an emergency on mine....

Every man has to know his limitations- Dirty Harry

PME from a pole transformer with less than the required two DNO electrodes, what's that called then?

Andy

Rough !


Stu

John,

I've told you before about following me around.

If you get a chance, email me the pics please.

I'm still trying to get back to last weeks problem to see what the outcome was but I'm off "up north" tomorrow to sort out a pig system


Stu

So where was the spark jumping to and from?

Andy

--"it was bound to happen i guess"

we are coming to that time of the year when issues like this are common
place.
trees grow, and wind blows. we cant change that but we will be there to
put things right, (even at 11oclock at night when armchair consultants
are tucked up in bed)
we cant also be there when consumers fail to maintain the PME bonding
requirements. you would think with the endless amount of information
available these days, with overpriced "guide" books on the market, these
simple errors on installations would be history.

thank goodness for the electricity board.

Regards.

John

Could I also request a picture please you had my email sometime ago, if you need it again then I can PM it.

Kind Regards

Daren

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..... Dont pee in my pocket and tell me its raining ......


www.quest-electrical-sw.co.uk

But in the old days when it was the "electricity board" tree clearances were done properly and as a preventative measure, these days it seems more a reactive approach.

Can't moan about my DNO though, they do play nicely nearly all of the time on emergencies and projects but perhaps I'm lucky in dealing with the right people.

Stu

'thank goodness for the electricity board'.

Well thank goodness for the spark I say, as most of the time we end up doing most of the donkey work. Last week I had a service moved for £1300.00. I had to lend the REC guys tools, tape, tails, show them how to wire a meter via a time clock, strip out the old service once it was dead. I may as well made the joint in the hole too while they sat in the van. it's becoming a very dangerous joke the way RECs cut back on staff, maintenance and quality

Now we come under Western Power we are OK as they have a helicopter for checking overhead lines in a cost effective way.

Andy

--"i am lucky in dealing with the right people"

essex boys, young fella, we will look after you!

Regards.

Are you suggesting that this fire was a result of a fault/error within the installation?
- Andy.

Daren


I have a new computer and lost a lot of email addresses in the change over so please PM me your email address and any one else who wants to see the photo.

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John Peckham

http://www.astutetechnicalservices.co.uk/

Regards

OMS

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Failure is always an option

PNB - ?? - TN-S ?? -

Regards

OMS

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Failure is always an option