Power cables for street lighting installations

[apprentice87]

Ok. well here is what i would be thinking, but i am no electrician!!

Now, you will have two big problems with TNCS in such situations..

1, The "perceived shock" thingy.. This could be dealt with by lots of rods, close enough together so that their areas overlap [or mesh in the ground, even better].. What i mean is, so as to ensure that all the ground area around any exposed conductive parts, is all at the same earth potential, as the exposed parts, which, as the supply is TNCS, might be quite different to "true" earth potential..

2, Next problem is a lost supply neutral. It would be nice to think that with all these rods/mesh whatever, that in the event of a lost neutral, that the combined effect of all the rods, would drag the touch voltage down to a safe level, but i doubt that very much.

Ok, stand by to laugh....Could not a device be rigged up, that measures, or monitors any PD between neutral, and say "true" earth, like a rod 100 yards away, and, if this PD rises to more than a few volts, cuts off the both the phase conductor AND the neutral... Hmm, oh yes, i do believe there already is one, an ancient VOELCB only one that worked with a difference of about 5 or 6 volts..

john..

 

[Andy™]

better still, get the DNO to go back to proper TNS, treat both line & neutral as live conductors

 

[apprentice87]

Exactly... The only reason they came up with TNCS, is because they could not be bothered to maintain the network properly. Do not forget that the DNO's have much more important things to worry about than safety. Making money for "Jonny Foreigner" shareholders is MUCH more important..

john..

 

[Andy™]

youre right, profit before safety

 

[Sidewinder]

...

1, The "perceived shock" thingy.. This could be dealt with by lots of rods, close enough together so that their areas overlap [or mesh in the ground, even better].. What i mean is, so as to ensure that all the ground area around any exposed conductive parts, is all at the same earth potential, as the exposed parts, which, as the supply is TNCS, might be quite different to "true" earth potential..

2, Next problem is a lost supply neutral. It would be nice to think that with all these rods/mesh whatever, that in the event of a lost neutral, that the combined effect of all the rods, would drag the touch voltage down to a safe level, but i doubt that very much.

...

Just taking the two points out of your post John.

1 would be taken care of by suitably designed additional earthing, and no you would not overlap the spheres of influence of the rods.

You need them to act independently.

2 Not a concern of the electrician.

This is covered by statute law, i.e. criminal not civil.

What needs to be done is that the law is implemented.

FFI's and a few fines based on the new levels would soon get the DNO's to sort their act out.

Combine this with individual accountability for those making the decisions, which must be made traceable, that endanger the public at large.

If the decision tree listing the accountability goes missing, CEO goes to prison & has to personally cover the fines.

That would sort them out.

 

[Sharpend]

Well it'd probably almost certainly send the foreigners home!! Then we might have our own infrastructure. 

 

[Andy™]

probably in the contract that they can take it home