Are Our Officials Too Risk Averse?

[Frank-the-Wool]

After a windy day today and a number of trees blowing down during the morning, one of which was a large Oak that completely blocked the top of a lane at a junction with the main road. Unfortunately the tree also brought down some power cables (insulated) that went to two houses. However the cable had pulled over the pole a small amount along the main road.

The police shut the main road, even though the carriageway was clear. The distance to drive around was some 10 miles and has taken up 4 police and two cars all day. When I said to one of the police that there is no problem getting by he said that it was not worth his pension as he could not make that decision.
When I asked what there plan was he said they were waiting for UK Power Networks to come and switch off the power so the tree could be cut up!

Had the cable been in a dangerous position or the pole likely to fall over then I could of understood there was a risk, but this was not the case and if one policeman with a vehicle had parked at the junction the traffic could have continued to flow!

 

[milkloss]

Is it the officials that’s the problem or the public looking for every opportunity to sue the crap out of all and sundry because of their own ignorance?

 

[TechWise]

I take your points on the overkill resources and I would usually be the first one to bemoan over the top caution.

However, during my time with a similar power company we were always warned of a time when a policeman thought he was doing the right thing by rolling a downed power cable off the road only to be killed when an auto-recloser re-energised the line. Most circuits can also be re-energised remotely from the control room and they will often remotely open certain switches and remotely re-energise the line to narrow down where the fault could be. For these reasons, it really is best to wait for the utility company to turn up. It is likely that plod had been told exactly the same thing.

 

[Hindsight]

I take your points on the overkill resources and I would usually be the first one to bemoan over the top caution.

However, during my time with a similar power company we were always warned of a time when a policeman thought he was doing the right thing by rolling a downed power cable off the road only to be killed when an auto-recloser re-energised the line. Most circuits can also be re-energised remotely from the control room and they will often remotely open certain switches and remotely re-energise the line to narrow down where the fault could be. For these reasons, it really is best to wait for the utility company to turn up. It is likely that plod had been told exactly the same thing.

Thank you for an informative post. I had a similar conversation with our local Western Power linesman last autumn regarding a post mounted transformer located adjacent to our garden - somewhat ironically in the corner of the cemetery!

 

[TechWise]

Thank you for an informative post. I had a similar conversation with our local Western Power linesman last autumn regarding a post mounted transformer located adjacent to our garden - somewhat ironically in the corner of the cemetery!

Something like 80% of overhead line faults are temporary in nature. For example, it could be that the wind blows two wires together. It's common to fit these auto-reclosers which trip then wait 10 seconds and try to reconnect then if it trips again it waits another 10 seconds. Usually they'll allow two or three attempts then it will lock off and send an alert to the control room that there's a permanent fault on that line. That's why it's best not to jump out of a loader tractor that has touched a line because even if the sparking seems to have stopped you just never know when the recloser might try to turn it back on or even how many times it will try it!

With underground cables, they usually come out of a substation, through a load of customers then back to the substation in a loop. If the cable develops a fault, it will trip at both ends at the substation and put all of the customers off. As soon as this happens, the control room is alerted and the "standby man" is already on his way. As he's heading to the scene, the control room will remotely open and close switches to break the line and different points. Each time, they'll try reclosing the breakers to see if they've isolated the faulted section. So again, if you put a digger through a cable, it will be isolated immediately but somewhere at a control room an engineer is looking at a map and thinking "I'll open that switch there to cut that line in half then I'll try turning it back on from both ends to see which half is dodgy". He presses "Ctrl+click" on a little picture of a circuit breaker and before you know it that cable you just dug through is live again!

 

[TheTallGuy]

After a windy day today and a number of trees blowing down during the morning, one of which was a large Oak that completely blocked the top of a lane at a junction with the main road. Unfortunately the tree also brought down some power cables (insulated) that went to two houses. However the cable had pulled over the pole a small amount along the main road.

The police shut the main road, even though the carriageway was clear. The distance to drive around was some 10 miles and has taken up 4 police and two cars all day. When I said to one of the police that there is no problem getting by he said that it was not worth his pension as he could not make that decision.
When I asked what there plan was he said they were waiting for UK Power Networks to come and switch off the power so the tree could be cut up!

Had the cable been in a dangerous position or the pole likely to fall over then I could of understood there was a risk, but this was not the case and if one policeman with a vehicle had parked at the junction the traffic could have continued to flow!

Plod isn't qualified to decide whether the pole/wires are safe or if there's an ancillary danger that he/she isn't aware of.

 

[DrWazzock]

Something like 80% of overhead line faults are temporary in nature. For example, it could be that the wind blows two wires together. It's common to fit these auto-reclosers which trip then wait 10 seconds and try to reconnect then if it trips again it waits another 10 seconds. Usually they'll allow two or three attempts then it will lock off and send an alert to the control room that there's a permanent fault on that line. That's why it's best not to jump out of a loader tractor that has touched a line because even if the sparking seems to have stopped you just never know when the recloser might try to turn it back on or even how many times it will try it!

With underground cables, they usually come out of a substation, through a load of customers then back to the substation in a loop. If the cable develops a fault, it will trip at both ends at the substation and put all of the customers off. As soon as this happens, the control room is alerted and the "standby man" is already on his way. As he's heading to the scene, the control room will remotely open and close switches to break the line and different points. Each time, they'll try reclosing the breakers to see if they've isolated the faulted section. So again, if you put a digger through a cable, it will be isolated immediately but somewhere at a control room an engineer is looking at a map and thinking "I'll open that switch there to cut that line in half then I'll try turning it back on from both ends to see which half is dodgy". He presses "Ctrl+click" on a little picture of a circuit breaker and before you know it that cable you just dug through is live again!

I understand that's how it works but would it not it be safer all round to actually investigate before reclosing the breaker?
I'm surprised HSE allow reclosure of a breaker onto a fault without prior investigation.

Can't they test the line for a fault remotely without applying lethal power, in order to ascertain which to isolate and which to reenergise?

 

[TechWise]

I understand that's how it works but would it not it be safer all round to actually investigate before reclosing the breaker?
I'm surprised HSE allow reclosure of a breaker onto a fault without prior investigation.

Can't they test the line for a fault remotely without applying lethal power, in order to ascertain which to isolate and which to reenergise?

This was quite an interesting discussion which was taking place in the company whilst I was there. As you point out, HSE don't like these types of devices as conventional wisdom tells people that when a cable stops sparking a fuse must have blown and it's now safe. The other side of the coin though is that OFGEM love them because it has lead to a dramatic improvement in the reliability of rural networks. Even in my lifetime (only 23), I can remember when I was younger almost every time there was a stormy night we had to look out the candles. Now, we very rarely have a power cut.

In terms of locating the fault remotely, there are of course ways of doing it but it all boils down to money. To locate an underground fault, they'll generally come round with the "test van" which fires high voltage pulses down the line and a person with a detector and a set of headphones can actually hear the fault crackling underground. Another option is the so called "reflectometer" which fires pulses down the line and listens for them bouncing back to locate the fault, a bit like sonar. This kit is ludicrously expensive. I think we had maybe three such vans to cover around half of Scotland. Imagine you installed this equipment in every substation just in case a fault occurred on a cable which may not happen for 50 years.

One interesting piece of technology they were working on just before I graduated were fault passage indicators, FPIs. These hang from the overhead lines and wait for a fault. When the fault happens they light up to say "the fault current went that way". Again, it's more money and to install them on every line is a LOT of communications equipment. When I was there, the FPI was something that a select few engineers carried in their van and they would use it to locate a known fault.

 

[DrWazzock]

Thanks for that interesting and informative reply.^^^

 

[Goweresque]

I think the police are generally far more risk averse than they used to be. They will close roads because of accidents at the drop of a hat nowadays, when in the old days they'd try to keep the traffic moving in almost all circumstances.

 

[ewald]

The police reflect society which is equally risk averse, hugely influenced by a legal system which punishes any actual or perceived misjudgement.
We end up with the policing we, as a society, deserve.

As a serving officer would you exercise any common sense? Or would you play safe and follow procedures?

 

[kfpben]

I think the police are generally far more risk averse than they used to be. They will close roads because of accidents at the drop of a hat nowadays, when in the old days they'd try to keep the traffic moving in almost all circumstances.

I would have thought that but a few weeks ago we had 3-400 cars stuck in the snow on a local A road. We were snowploughing and towing them out.

I asked the utterley useless policeman to close the road as it was blocked in both directions, with traffic being added all the time and cars shunting into each other.

‘Nah can’t close the road’ was the answer. ‘I don’t have authorisation’.