DNO temporary generators

If the network contains any PME then an RCD is not possible, as it sees it as  an NE fault.

A genset on skids in the mud may well be its own electrode of 50-100 ohms, and that will be augmented by bonding at the houses that have metallic services.

The path through the terra-firma ground is not the main fault loop for blowing fuses - that is done via the neutral/ CPC .

The sort of gensets that DNOs have on 'call-off' with the likes of Agrekko have earth fault relays, because all hire gen-sets do, but when used for network support they are likely to be either off or set to a level rather more than the likely neutral current,  to avoid the PME issue.

A modest genset for a few houses may not blow a 400A fuse like the substation would, though a house fuse at  60A or 80A should be in reach if a bit slow,  but even  if the fuse does not blow the volts will collapse or the genset will stall, so it is an awkward and flickery problem  rather than a dangerous outcome.

Mike.

(The new forum? It's ok... plus, it's FREE! Nice!!).

Hi, I was going to raise a few questions' regarding this. A week ago my neighbour was knocking on my door to say he had no power... turned out that there was a problem with the SWA cable, in the street. For a few days' we had an enormous, (and, haha, noisy), generator. I live in a small close and you could hear it humming away BUT, at least he had power!

The other thing is, his wife is very disabled and they have 'local service helpers' popping about 4 plus times a day! So, quite a lot of foot traffic! 

H&S???

1 - Is this right? They ran an SWA, from the generator, through his letterbox!! I mean... there MUST be some code that this isn't acceptable? 

2 - See the photo of the TT supply. 

Any suggestions?

regards...

CLICK phots' to enlarge!

SWA Through the letterbox!

 TT supply to the house.

OK, you could argue how would you get the required SWA into the house? My answer would be... drill a small hole somewhere... wouldn't that be better??

DAMN!! I clicked a wrong sign to report this!!! SORRY!!!! 

That letterbox  is indeed a class act. Had they said something to upset the team I wonder ? (shades of the ununlucky Mr Meldrew). Traditional way in would  be a fanlight window and if needed a couple of bits of chipboard one inside one outside screwed together to form a clamp to stop the draught.  I imagine there is no reg broken, apart from the one about good practice, but the earth rods look a bit shallow and rather close to each other to get the low ze  benefit of parallel connections.

Mike

Thanks Mike... I just laughed, when I noticed this. 

regards...

Cables through letterboxes are in my experience a common approach in this situation. Almost every home has one so it is a simple and quick way of restoring power.

Drilling holes takes longer and risks damage.

Cables through letterboxes are in my experience a common approach in this situation. Almost every home has one so it is a simple and quick way of restoring power.

Drilling holes takes longer and risks damage.

https://www.youtube.com/watch?v=lNEXWITxkmg

May be of interest, cables through letterboxes for some customers. Others restored by temporary connection of generators into the street mains.

Fair enough... thing was I haven't seen that done before. At least they had power!

regards...

Have done it that way in the past when I worked for a DNO even used 6.0mm t&e.

Something to be to be aware of from the customers point of view, is that two approaches exist for temporary supply from a generator.

Firstly is an extension lead, probably with a 32 amp male plug and several 13 amp sockets, the other way is a temporary cable connected in place of the usual service cable.

The extension lead is less convenient since only appliances plugged into this lead can be used.but has the merit that the supply is not metered, a significant saving in some cases.

The temporary cable in place of the usual service cable will energise the whole installation as normal, but the power passes through the KWH meter and is charged for.

I once had a 32 amp extension lead for a week, free electricity for a week. though limited to 32 amps. I plugged into this lead my existing UPS, a couple of 1.5 kw heaters  and either the washing machine, or any other heavy loading appliance, or another heater.