The effect of stealing copper

[westie101]

http://www.bbc.co.uk/news/uk-england-leeds-14075618

probably stole the neutral earth connection in a substation!

Though this one paid the ultimate penalty

http://www.bbc.co.uk/news/uk-england-leeds-14059274

 

[sparkticus]

This sort of insane crime seems to be on the increase!!

 

[wotan]

Boy with pliers. electric wires...blue flashes....boy ashes

 

[adlplumbing]

who cares one less theif

 

[stardanny]

http://www.bbc.co.uk/news/uk-england-leeds-14075618

probably stole the neutral earth connection in a substation!

Though this one paid the ultimate penalty

http://www.bbc.co.uk/news/uk-england-leeds-14059274[/QUOTE]

Please explain how nicking neutral earth connection cause fires?

Dan.

 

[sparkticus]

http://www.bbc.co.uk/news/uk-england-leeds-14075618

probably stole the neutral earth connection in a substation!

Though this one paid the ultimate penalty

http://www.bbc.co.uk/news/uk-england-leeds-14059274[/QUOTE]

Please explain how nicking neutral earth connection cause fires?

Dan.

Only a guess but I assume the neutral earth connection then takes a new position in Mrs Smiths meter cupboard where Mr Smith (who loves electrical DIY) connected a G/Y to the neutral of his consumer unit.
That G/Y which was only 10mm is now on fire (as is the laundry basket which is next to the gas meter) due to carrying multiple fault currents for his and three other streets.

 

[flameport]

Please explain how nicking neutral earth connection cause fires?

The usual problem is that the voltage between line and neutral which is should be around 230V will rise to anything up to 400V.

Appliances designed for 230V generally go bang when 400V is applied to them.

 

[efiste2]

This problem is getting worse by the week for the DNO I work for.....I dont know the location, but we have recently had what is called a Primary S/S broken into (primary S/S is 33kv to 11kv stepdown). The thieves stole that many parts from the 11kv switch-board that it is a write off as spares are no longer made, this now means the fitting of a "temp" board to keep the network running, whilst the old board is recovered and a new one put in its place. These cost hundreds of thousands of pounds. Apparently we are having an average of FOUR secondary substations (11kv to 415v) broken into per day and anything thats copper and not live taken.....We believe The people that are doing this have inside info and in some cases access keys.....as they know exactly what NOT to touch, and in some cases what switches to open to make things "not live" and ready to strip.....even heard of some rogues who not only take the copper/metals, but also take the insulationg oil to run cars/vans with!!!!

 

[efiste2]

Ive seen many instances where Neutrals have been left off overhead transformers and cause utter choas on properties fed off them.....The transformer(Delta/Star winding) secondary output as flameport says has no reference point eg the earthed star point, and therefore the secondary output voltages can vary dramatically!!! electronic devices seem to be very prone to it....

 

[sparkticus]

What about earth fault currents? Won't they become focused in other areas with smaller conductor sizes such as Mrs Smiths meter cupboard (and burn up) Or will the various other DNO neutral-earth points along the rout act as a backup?

having said that, its only TN-C-S that has the backup connection is it not?

I guess that could happen with a TN-S system?

 

[westie101]

our record for loss of N/E connections due to theft at substations was 750+ customers affected, fortunately without the effect of this one (but a lot of near misses)

 

[mfarrow]

The thieves stole that many parts from the 11kv switch-board that it is a write off as spares are no longer made

I'm surprised at this, surely there's someone out there who can make the parts necessary, and prevent you having to replace the board completely.

How old was the board and who made it?

 

[bernardgreen]

Please explain how nicking neutral earth connection cause fires?

Assuming the outgoing neutral is still connected to the transformers star point and only the copper between earth and star point has been removed.

At first glance disconnecting the earth from the neutral at the substation should not create a situation where there is a risk of fires. The voltages between phases and neutral will still be 230 volt so supplies to properties will still have 230 volt phase to neutral. The voltage neutral to earth however will no longer be defined and the neutral will be floating and will tend to be the potential of the transformer casing. If that is no longer earthed then it will assume a voltage by capacitive coupling with the incoming 11 Kv supply. This could result in neutral being several Kv above ground. It will not need much capacitive coupling at 11 Kv to get enough power onto the neutral to damage any neutral to earth connection / bonding at customers premises and any earthing points on a network with PME supplies. The return path for this current is via the ground to the start point of transformer from where the 11 Kv is coming from.

Fortunately but not always the 11Kv to 230v / 415v transformers are constructed such that the voltage capacitively coupled onto an unearthed casing is unlikely to be anywhere near 11 Kv

The thieves have no idea of the danger they create. Or if they are aware of the danger then they are seriously lacking in empathy for the people they are putting at risk.

 

[efiste2]

How old was the board and who made it?

I dont know the details Im afraid so i can only assume it was an older board, many of the 11kv switchboards are 50 - 60 years old uisng oil insulated circuit breakers and bitumen compound filled bus-bar chambers and the only source of spares we have are from units recovered from other subs, The manufacturers such as Johnson & Philips or South Wales Switchgear have long since been either closed or amalgamated into other companies....Im sure the parts could be fabricated but as with everything COST is the number one factor so it must have been more economical to change the board, also Scot Power will use this as an oppurtunity to get older switchgear of the network....

 

[mfarrow]

I guess at that age it is more economical to build a new one.

I was thinking of a Whipp & Bourne we had which blew a while back, knocking out 3 breakers and a bus-coupler adaptor. A new board itself would have been fairly cheap, but once you consider the cost of design, new cable routes, SCADA, protection study, maintenance training etc. the refurb won it!