Flash Overs

[ban-all-sheds]

He was not inducted onto the site, was not wearing PPE, and was hospitalised as a result.

Can you give me one good reason why everybody up the chain from site manager to chief exec of the company should not have gone to jail because of that, and any credible theory as to why if everybody up the chain from site manager to chief exec faced prison time there would still be instances of people not being properly inducted?

In general likelihood of detection is always preferable to strong punishment as a dterrent, but if we can't afford the former then we have no choice but to go with the latter.

 

[ban-all-sheds]

It is very common in the states for each house or two to have there own tranney

Yes, but what about their electricity supply?

 

[westie101]

He was not inducted onto the site

Which does lead to some interesting discussion as the DNO is not legally classed as a contractor or directly under the control of site management.

Whilst it is true that we should co-operate with site staff we are there most of the time to carry out our statutory duties for which we have a legal right of access.

In a recent one a colleague had a discussion about jointers wearing safety helmets where there was no overhead work within a few hundred metres. It was pointed out that even the HSE does not agree with this sort of overall "safety" rule as it does in effect reduce safety by instilling complacency in the workforce. It took the threat of us leaving site and putting a stop to the contract to get them to see the point!

(there is no legal need for site induction BTW)

 

[RF Lighting]

He was not inducted onto the site, was not wearing PPE, and was hospitalised as a result.

Can you give me one good reason why everybody up the chain from site manager to chief exec of the company should not have gone to jail because of that, and any credible theory as to why if everybody up the chain from site manager to chief exec faced prison time there would still be instances of people not being properly inducted?

In general likelihood of detection is always preferable to strong punishment as a dterrent, but if we can't afford the former then we have no choice but to go with the latter.

Maybe they did. I don; know the out come of the incedent, but I do know that the HSE were on site the next day carrying out their investigations.

 

[westie101]

but I do know that the HSE were on site the next day carrying out their investigations

More likely investigating the breeches of the DNO safety rules etc. (the NW Electrical inspectors are based in Manchester)

 

[Porque223]

As safety goes ^ production goes \/. Economists have graphs for this and each manager can then dial up how many dollars he wants to save for some reasonable certainty for burns, blindness and fatalities for his workers.

Apparently the Peanut Corporation of America poisoned many people and not one of the many employees blew the whistle. Not all of these employees were sociopaths but I guess they had families to feed.

Some regulatory agencies are Tombstone Agencies; they regulate by counting tombstones. And with regard to the questioned safety of an airline company one guy actually said out loud, "Not enough people have died yet."

BTW, it's about 10 houses per 7.2KV: 240v transformer and the house at the end of the run may only have 3kA short circuit current.

 

[streetlighter]

Where i used to work we had an incident last year involving a flashover in a DNO cutout in a street lighting coulmn.
The Operative was inserting the fuse carrier after replacing the fuselink and there was a flashover.
He was not wearing any PPE as in insulated gauntlets and a visor and suffered burns to his hand.
Quite lucky the local hospital was accross the road from where the incident happend.
Ive had a few cutouts go off on me especialy the older black Lucy type.

 

[MeterMonkey]

I have seen many 'sparks' when inserting a fuse back in the cutout, but have never had a flash.

Westie, do you know of the main cause to flash overs?

 

[JohnW2]

Westie, do you know of the main cause to flash overs?

One would have thought that it would be possible to design a plastic cutout which, certainly if used properly, ought to be more-or-less immune from L-N (or L-'E') flashovers (except, perhaps, when the cutout itself was being installed or removed), which I presume is what the nasty ones are. The L-side could be totally insulated from the N/CNE side, with separate access - and, if one even wanted immunity from people not 'using it properly', there could even be interlocks which prevented both L and N sides being 'opened' simultaneously. Nothing short of total diintegration of the whole thing should then allow L and N to come into contact. I wonder how close modern cutouts come to that 'ideal'?

Removing or re-inserting a fuse 'on load' can presumably result in some nasty arcing - but if there's not any N (or 'E') around, it's hard to see how a true 'flashover' could occur.

Kind Regards, John

 

[Wontdothatagain]

As far as i know, the majority of faulty service heads that flash over are caused by overload/heating of the service.

 

[JohnW2]

As far as i know, the majority of faulty service heads that flash over are caused by overload/heating of the service.

Should they not be designed such that no serious damage would be done to the cutout at currents that did not cause the fuse to operate?

Kind Regards, John

 

[Porque223]

There can be quite a bit of energy in an arc flash.
http://ecmweb.com/content/calculating-arc-flash-energy-levels[/QUOTE]

The last time i went for my compentency update, the calculation in that link was used to show some new meter ops the energy that can come out of a service head and it equates to a small car hitting you in the face a 5 MPH

This is equivalent to running your face into a wall at seven feet per second and I'd think even one foot per second would be unpleasant.
And the quicker your face comes to a stop the more power is dumped into it.

 

[ban-all-sheds]

This is equivalent to running your face into a wall at seven feet per second

Only if your mass is the same as a small car.

 

[westie101]

Should they not be designed such that no serious damage would be done to the cutout at currents that did not cause the fuse to operate?

They are!
The system is designed that they should not be overloaded if folk follow their contract of supply, but we've seen where that leads us when we have discussed that aspect of electricity supply!

 

[JohnW2]

Should they not be designed such that no serious damage would be done to the cutout at currents that did not cause the fuse to operate?

They are! The system is designed that they should not be overloaded if folk follow their contract of supply, but we've seen where that leads us when we have discussed that aspect of electricity supply!

You can't trust people. I meant literally what I wrote - that they ought to be designed so that they would not come to serious harm at any current, even continuous, that was insufficient to cause the fuse to operate. Since one can't trust people, that's surely the only 'safe' approach?

Kind Regards, John