Builder needing advice after damaging temporary supply to new build!

[shaun rosier]

Hi Everyone,

I would really appreciate some advice on the following problem I have had with a temporary electric supply.

We are in the process of building a couple of flats and had a temporary supply put in, no problem! However much later when one of the labourers was putting the hockey sticks into the new boxes and needed to bust through some of the footing he stupidly damaged the cable with a breaker and grazed the cable exposing the outer sheath (cable was not severed) and there was a load bang and the cable started fizzing in the hole which was filled happened to be filled with water!

We called the supplier out to repair and two guys turned up to repair the cable and one of them got a zap of the cable as he tried to repair it. Before this the same labourer got a zap off the site cabin handle after he went through the cable.

We then had the two neighbours that lived down the lane come out and say there TVs had blown up!

The engineer said that there was no way that us going through the cable would have caused the TVs to blow and it was just a coincidence! I just don't believe that as it happened at exactly the same time!

He then called his boss and about 5 vans pulled up within about 20mins and started to take down the over head cables to the main road. They replaced a stretch of the cable and were working on one of the poles.

I don't remember exactly what our sparky said but he thinks that the supply cable had an existing fault and that the sheathing was somehow live and that's what caused the cabin to become live when it was damaged and the cable was possibly 'vibrating' and caused a surge down the line to blow up the TV's. This he says may be why the engineer got a shock as he didn't expect the sheathing to be live!

The reason why I could really do with some advise on this one is because the supplier is charging me for the whole team that turned up (about 6 guys) for about 5 hours with the overhead work when I was just expecting to pay for the two guys for a couple of hours to fix my temporary supply not half the road! I have offered to pay them what I think is fair but they say they will bring me to court if I don't cough up in full!

Any advice would be most welcome from the pros!

cheers

Shaun

 

[Dave OCD]

Shaun

First off I'd say the labourer was rather foolish to be using a powerful breaker in an area where it was obvious there was a buried mains cable. It will be nigh on impossible to prove that all of the following issues were not associated with the initial cable strike and the best you can do is try some negotiation with your DNO.
Your Sparks isn't making sense to me with his theories, sorry this isn't a very helpful reply but I'm just being honest as I see it mate.

 

[LankyWill]

Who’s the company and how much they asking?

 

[LankyWill]

Secondly, who employs the labourer? If you have employed builders under a contract, pass the bill to them.

 

[westward10]

Sounds like an episode of Some Mothers Do Ave Em.

 

[paleosparky13]

Hi Everyone,

I would really appreciate some advice on the following problem I have had with a temporary electric supply.

We are in the process of building a couple of flats and had a temporary supply put in, no problem! However much later when one of the labourers was putting the hockey sticks into the new boxes and needed to bust through some of the footing he stupidly damaged the cable with a breaker and grazed the cable exposing the outer sheath (cable was not severed) and there was a load bang and the cable started fizzing in the hole which was filled happened to be filled with water!

We called the supplier out to repair and two guys turned up to repair the cable and one of them got a zap of the cable as he tried to repair it. Before this the same labourer got a zap off the site cabin handle after he went through the cable.

We then had the two neighbours that lived down the lane come out and say there TVs had blown up!

The engineer said that there was no way that us going through the cable would have caused the TVs to blow and it was just a coincidence! I just don't believe that as it happened at exactly the same time!

He then called his boss and about 5 vans pulled up within about 20mins and started to take down the over head cables to the main road. They replaced a stretch of the cable and were working on one of the poles.

I don't remember exactly what our sparky said but he thinks that the supply cable had an existing fault and that the sheathing was somehow live and that's what caused the cabin to become live when it was damaged and the cable was possibly 'vibrating' and caused a surge down the line to blow up the TV's. This he says may be why the engineer got a shock as he didn't expect the sheathing to be live!

The reason why I could really do with some advise on this one is because the supplier is charging me for the whole team that turned up (about 6 guys) for about 5 hours with the overhead work when I was just expecting to pay for the two guys for a couple of hours to fix my temporary supply not half the road! I have offered to pay them what I think is fair but they say they will bring me to court if I don't cough up in full!

Any advice would be most welcome from the pros!

cheers

Shaun

Overhead lines 400+kv 33kv carry very little current less than a house. 11.5kv sub mains and sub rings carry more current and hence more magnetism. Might be interacting with your sites centre tapped tranny. Not sure.

 

[Dave OCD]

Eh ?

 

[westward10]

I cannot believe your damaged cable and the need for replacing overhead lines are remotely connected. You need to ask for a technical report outlining the cause and effect of what has supposedly occurred.

 

[paleosparky13]

Eh ?

Eddy currents?

 

[Dave OCD]

I thought they replaced the damaged underground supply which originated from an existing overhead line ?

 

[Toneyz]

That's what insurance is for.

 

[shaun rosier]

Hi Dave,

Your right! the labourer was careless but he thought he was well away from the supply as when the temporary cable was put in, it was put in a big loop for some reason and was just an inch off the foundation where he wanted to bury the hockey stick in. He was working on the premise that the cable was running in a roughly straight line from the main post to the temporary meter.

 

[Dave OCD]

Eddy currents?

Yes I know what you mean but can't see any relevance in relation to this particular tale of woe.

 

[shaun rosier]

They repaired the cable in the ground after they changed the overhead cable on the main road.

 

[Dave OCD]

Hi Dave,

Your right! the labourer was careless but he thought he was well away from the supply as when the temporary cable was put in, it was put in a big loop for some reason and was just an inch off the foundation where he wanted to bury the hockey stick in. He was working on the premise that the cable was running in a roughly straight line from the main post to the temporary meter.

Easily done, there's a defence straight away, temporary or not the cable should have been at a sensible depth and covered in warning marker tape, I'd suggest 500mm minimum.

 

[westward10]

Don't pay a bean until you have a technical report which you can then pass on to an electrical engineer, not an electrician.

 

[paleosparky13]

Yes I know what you mean but can't see any relevance in relation to this particular tale of woe.

I don't believe eddy currents actually exist in reality. But I doubt a distribution network would take those chances. Covering their asses. Is our our infrastructure effecting their site or are they at faukt?

 

[paleosparky13]

Yes I know what you mean but can't see any relevance in relation to this particular tale of woe.

I don't believe eddy currents actually exist in reality. But I doubt a distribution network would take those chances. Covering their asses. Is our our infrastructure effecting their site or are they at faukt?

 

[shaun rosier]

why would the engineer get a shock, the cabin get lived up and the TV's blow down the lane?

Surely something was wrong with the cable! that can't be normal?

 

[westward10]

It is impossible to speculate you need to ask for a technical report which you can forward for further guidance. Asking for this and stating why you require it may well throw them.

 

[Toneyz]

Was it a PME supply to the office, canteen etc. if you had a loss of neutral?

 

[shaun rosier]

I cannot believe your damaged cable and the need for replacing overhead lines are remotely connected. You need to ask for a technical report outlining the cause and effect of what has supposedly occurred.

Hi Westward,

We did ask for a report and they said they would not give one unless we signed a confidentiality agreement! That's why I'm even more suspicious that the cable was faulty!!

 

[shaun rosier]

Was it a PME supply to the office, canteen etc. if you had a loss of neutral?

Sorry Anthony! I don't know what a PME supply is! The temporary supply came to the temporay meter and then was taken off this to supply our canteen/office. After the damage to the cable the labourer got a shock off the cabin handle!

 

[The Ghost]

Have you asked about this on the IET site, more engineers on there may help? The DNO is responsible for the supply and infrastructure of your supply. Sounds like this will involve solicitors. Of course you could make a counter claim for loss of work time and damages for employees etc.

 

[Toneyz]

Sorry Anthony! I don't know what a PME supply is! The temporary supply came to the temporay meter and then was taken off this to supply our canteen/office. After the damage to the cable the labourer got a shock off the cabin handle!

It is where the neutral and earth of the consumer's installation is joined together so on the supply side you have the live conductor and the outer armouring in the combined neutral/earth conductor.

 

[shaun rosier]

It is where the neutral and earth of the consumer's installation is joined together so on the supply side you have the live conductor and the outer armouring in the combined neutral/earth conductor.

Yes I remember our sparky telling me about this type of cable, so I think it was a PME supply.

 

[shaun rosier]

Have you asked about this on the IET site, more engineers on there may help? The DNO is responsible for the supply and infrastructure of your supply. Sounds like this will involve solicitors. Of course you could make a counter claim for loss of work time and damages for employees etc.

Thanks for the advice Vortigern!

 

[LankyWill]

DNO will only install a temporary supply using TT, they insist on having the Earth Rod in place or they won’t connect meters.

 

[Richard Burns]

No matter what happened to the incoming cable at your temporary supply the electrical supply network should be able to handle any fault that occurs without causing damage to their system.
If the fault caused damage to their network then this would only be highlighting an error in their network which should not be down to you to cover.
Damaging a supply cable in the manner you describe should not cause a bang as the fault would be to earth and not the conductors, unless it earthed via the breaker if it was electrical. If the damage were such that the cable sheath contacted the internal live this would cause a short and a bang and may well disconnect several properties power supplies as it takes out the supply fuse(s) and this would be chargeable to the person or company responsible for the fault.
However I do not know the legalities of such a situation.

 

[shaun rosier]

No matter what happened to the incoming cable at your temporary supply the electrical supply network should be able to handle any fault that occurs without causing damage to their system.
If the fault caused damage to their network then this would only be highlighting an error in their network which should not be down to you to cover.
Damaging a supply cable in the manner you describe should not cause a bang as the fault would be to earth and not the conductors, unless it earthed via the breaker if it was electrical. If the damage were such that the cable sheath contacted the internal live this would cause a short and a bang and may well disconnect several properties power supplies as it takes out the supply fuse(s) and this would be chargeable to the person or company responsible for the fault.
However I do not know the legalities of such a situation.

No matter what happened to the incoming cable at your temporary supply the electrical supply network should be able to handle any fault that occurs without causing damage to their system.
If the fault caused damage to their network then this would only be highlighting an error in their network which should not be down to you to cover.
Damaging a supply cable in the manner you describe should not cause a bang as the fault would be to earth and not the conductors, unless it earthed via the breaker if it was electrical. If the damage were such that the cable sheath contacted the internal live this would cause a short and a bang and may well disconnect several properties power supplies as it takes out the supply fuse(s) and this would be chargeable to the person or company responsible for the fault.
However I do not know the legalities of such a situation.

That's exactly what I thought Richard, sounds like they are trying to blame me for a fault in there network! The engineer got a shock when he touched the outer sheathing wires as he took his gloves off, he obviously wasn't expecting them to be live!

 

[PEG]

That's exactly what I thought Richard, sounds like they are trying to blame me for a fault in there network! The engineer got a shock when he touched the outer sheathing wires as he took his gloves off, he obviously wasn't expecting them to be live!

Really? Testing after safe isolation is mandatory,and would be all the more prescient after damage.
Who exactly was he? The answer is NOT an engineer...

 

[Rpa07]

Good thread, sorry about all the grief you’ve had @shaun rosier - the original post read like the opening scene of Casualty!

 

[Wilko]

Hi - thoughts from me - I don't see you having to pay out for overhead cable works - talk to your insurance co. and they may provide legal-eagle to assist. Just having legal-eagle ask for the @westward10 technical report will cause a sharp intake of breath, because they know it will be independently reviewed.

 

[buzzlightyear]

being a TT system they would have putted the fuse at the substain or the link near the transformers before any work carried out ,by saying this did your labour not think before hand by getting a CAT. and not a cat with two eyes .

 

[shaun rosier]

Good thread, sorry about all the grief you’ve had @shaun rosier - the original post read like the opening scene of Casualty!

Ha, Ha! If you didn't laugh you'd cry!

Thanks for all the help guys! much appreciated!

 

[buzzlightyear]

Ha, Ha! If you didn't laugh you'd cry!

Thanks for all the help guys! much appreciated!

don't go yet ,we need to discus about the big bill your getting, 5 grand bill heading your way.

 

[davesparks]

Hi Dave,

Your right! the labourer was careless but he thought he was well away from the supply as when the temporary cable was put in, it was put in a big loop for some reason and was just an inch off the foundation where he wanted to bury the hockey stick in. He was working on the premise that the cable was running in a roughly straight line from the main post to the temporary meter.

The labourer may have been careless but was he following the safe system of work you had put in place for him? Did you carry out a risk assessment and method statement?
Did you survey they ground he was digging in with suitable cable locating equipment before he started digging?
Did you enquire as to the location of the cable with the electricity supplier before work started?
Did you take all reasonable steps to ensure that this man’s life was not put at risk before he started work?

If he had lost his life could you honestly face his family, the judge and your conscience and say you did everything you could to prevent it?

 

[buzzlightyear]

If he had lost his life could you honestly face his family, the judge and your conscience and say you did everything you could to prevent it?

yes milord , if some one had lose their life HSE would be over it like CSI .

 

[PEG]

Yep,and book me a seat in the public gallery...i want to hear that "engineer" explaining how he "shouldn't have got a shock of that bit..." and how he never looks to the left when crossing the road,in this country...

 

[telectrix]

Yep,and book me a seat in the public gallery...i want to hear that "engineer" explaining how he "shouldn't have got a shock of that bit..." and how he never looks to the left when crossing the road,in this country...

i always look to the left, and to the right. which way is the nearest pub?

 

[littlespark]

I believe the question is “did the incident on the building site cause the damage to the suppliers cable, or was the damage there before?”

Answering this will ascertain who needs to pay for the repair job and 2 tellys.

Maybe you need to get a professional in. Ie, a lawyer.
Unfortunately questions will be asked about safe working practices, and HSE will get involved.

Hopefully no one was seriously hurt, but left undiscovered, the fault could have been catestrophic.

 

[westward10]

HSE won't get involved.

 

[buzzlightyear]

maybe jack hammer Charlie was left loose ,tight have caused a spike on the cable .the op said the cable was only grazed. but we are not there .but we can only take this word .

 

[Pete999]

Eh ?

Double Eh

 

[Pete999]

Eddy currents?

Explain please

 

[Squid]

Explain please

 

[Lucien Nunes]

Ignore eddy currents, C/T-E site trannies etc, all irrelevant. If the overhead cable affected was the LV 400/230V supply to the property, I read the scenario as follows:
1. There was an existing defect on the DNO's CNE conductor or connection to it. Not your property, not your fault.
2. The builder caused an L-E or L-N fault on the service cable to your property. In the time it took for the OPD to clear it, the existing defective CNE / neutral connection or cable went open-circuit.
3. This left some consumers on a 3-phase distributor sharing a disconnected neutral, leading to incorrect L-N voltages. Some of them received more than 230V, blowing up their TVs.
4. Your site was also left with an open CNE resulting in tingles / shocks to anyone touching it outside the equipotential zone.
5. The DNO's team had to repair the distributor first, as this was preventing them supplying other customers.

Actually, was it the service cable (before the meter) or your submain (after meter) that was hit?

 

[johnduffell]

I don't understand the talk of PME - how on earth does the equipotential zone work on a construction site? The only way to ensure safety would be to use a local earth for all CPCs otherwise you risk introducing other potentials through the supplier provided protective connection.

 

[Midwest]

Guess the supply cable would be PME (i.e. the one damaged), the building site temporary's connected to TT, unless all extraneous conductive parts are connected to the MET.

 

[ruston]

@Midwest . Yes it depends how diligent they have been with the temporary supply. Nothing goes wrong until it does.