Anyone know about SNE?

[Rockingit]

Got a new supply on a site, DNO delivered it as an SNE (so that's TN-S, yes?), 80A fuse in a 100A labelled head (yes, very clever).

But, I was there when they did it and they only ran a 'single' concentric 16mm in straight from the pole, so I can't see where the N/E separation is at all. Got a Ze of .67 so it's behaving like a TN-S.

But also, as I understand it, the DNO's aren't supposed to provide end dwellings with TN-S straight off the pole?

I'm going to be getting in a bit of a bun fight with them (DNO) over something else soon, so I'd like to be as overall gen'd up as possible!

Cheers.

 

[Knobhead]

I asked about this on another site, I’ve now got drawings from America, Canada and India! I’m more confused than ever now! The American 120/240V system looks great for:
A/ blowing yourself up
B/ frying your appliances
One guy in Kansas lost the neutral bonding to his house so the 120V appliances were working in series! The earthing to his house is purely the water pipe.

PS Any photo’s yet?

 

[Rockingit]

LOL. What on earth have I started?!! Took a couple of pics which are still on the camera so I'll upload them when I grab it out of the wagon.

Just going to send you a pm, by the way.

 

[mhar]

It is common practice for Westerm Power to put in 80A fuses even though it is a 100A carrier, I am told that this is because 80A is their standard supply. A completely unofficial reason is because they had problems with some cutouts melting before the fuse (100A) blew!

 

[Rockingit]

I don't have an issue with 80A as a supply (normally!!) but I do think it's a fairly basic error to keep the heads labelled as 100A. That 20A that doesn't exist could lead to all sorts of problems!!

And now, especially for Tony, some pictures of a transformer on a pole.

 

[johnboy6083]

whats the outcome of this fellas?

 

[johnboy6083]

is the central wire on the O/H supply, actually the HV earth, that will be tied to ground at a pole some distance away?

 

[Engineer54]

According to the DNO, one of them is an earth conductor, but try as i might, i can't see a connection to earth from any of them. It was obviously once a 3 phase distribution system on that pole, but now looks a bit of a lash up, and difficult to distinguish what is what from the provided photo's.

 

[johnboy6083]

According to the DNO, one of them is an earth conductor, but try as i might, i can't see a connection to earth from any of them. It was obviously once a 3 phase distribution system on that pole, but now looks a bit of a lash up, and difficult to distinguish what is what from the provided photo's.

i was trying tro trace the wires also, but as you said its impossible.

 

[johnboy6083]

What i did manage to work out is that the stud on the right of the tx is connected to the same conductor as the tx shell. That means that must be the neutral, which is then earthed.
the stud on the left must be the line conductor. I cannot see any other earth though.

 

[Rockingit]

I can't even see myself when on site! Like you say, it's a bit of a mess really. But hopefully, they'll rip it all out when they put me in a 3 wire.........

 

[Knobhead]

A separate earth isn’t run on 11KV OH supplies. In the 2[SUP]nd[/SUP] photo you can just see a pin insulator for the centre phase.

To be honest it’s a mess. I can’t see a neutral/earth connection anywhere. They could have connected at the heat shrink break out of the split concentric but we can’t see it.
I still can’t fathom why the DNO would change the guts of a transformer rather that change the whole unit, it’s just not cost effective!

The best bet for the future is yet another change of the transformer guts. It’s the only way forward, be it a 30KVA single phase or a 15/15KVA three wire.
I don’t like 3 wire because of interaction of secondary windings under unbalanced load.

A three wire transformer can be wired two wire, (just to muddy the waters even more). They are both the same transformer!

Sorry!

View attachment 8935

 

[Engineer54]

Tony,

Only going by what the DNO told the OP. Personally i can't see that TX being shown, was ever a 3 phase TX on the HV side. Maybe it's a replacement unit, as you say, converting the guts isn't cost effective at all. Better to whip it down and use elsewhere and replace with a single phase TX. Whatever, looks like a real mess on that pole, it needs striping of all the old redundant stuff and starting again...lol!!

 

[Knobhead]

In your dreams E54.

The DNO's have no pride! (Couldn't give a ----).

 

[mhar]

Bit harsh Tony.
My youngest is a linesman for Western Power. He takes pride and it is appreciated. Because of this he gets called out a lot as the job will always be done to the best of his ability, will be neat, polite to the customers, considerate and he is given trainees/apprentices so that they can learn his ways. Same with electricians (and most trades), people ignore / don't notice all the thousands of good jobs and focus on the bad

 

[Engineer54]

In your dreams E54.

The DNO's have no pride! (Couldn't give a ----).

Errrr!! .... What's in my Dreams??