High Ze Cable Calcs 20 characters

[tomspark93]

So I have a job to quote for installing an outdoor sub main. It's in quite a rural location and the supply seems to be TNCS. However, there is another conductor that leaves the MET and looks like it could possibly go to to a rod (the cable that leaves through a hole just to the left under the meter tails) This might be part of the DNO's earthing if its end of line I guess.

I've measured Ze at 2.72 ohms. Where do you stand in regards to cable calcs? Obviously first port of call is to ring the DNO and see what their stance is on it.
However, if they are disinterested whats the best port of call? It doesn't seem right designing a circuit that cant meet disconnection times. I know TT installs we'd use RCD's to meet the requirements for fault protection. Would it be the same in this instance?

The covers are only off them henley blocks for testing purposes

 

[westward10]

Did you take a line to neutral loop reading.

 

[buzzlightyear]

what are you supplying regards the sub mains !

 

[Leesparkykent]

Does it drop down a pole before entering the ground and up to the cutout? Could be PNB if the pole has TX mounted onit.

 

[tomspark93]

I couldn’t see where the pole was unfortunately. There was heavy greenery behind the existing meter cabinet which is externally located at the end of a track. I’ll nip up tomorrow and have another look as it’s not far from where I am working.

The sub main is potentially going to a steel frame around 160m away which will feed the rugby clubs new electric score board and from there it will potentially branch off to feed a couple of heaters in the dugouts and also a socket in a camera stand.

 

[buzzlightyear]

imo you should ring the DNO and ask them what system they have put in before going a head with the sub mains .

 

[buzzlightyear]

looking at the google map, TT from the DNO ? and then on to the sub main.

 

[tomspark93]

looking at the google map, TT from the DNO ? and then on to the sub main.

I'll ring Northen Power up tomorrow and see what they say. They are usually quite helpful. I would have thought the same apart from the earth entering the service head.