Has this any failings do you think? The door can be replaced.

With the design of these enclosures, the door has to be fully opened to allow it to be removed from the pin hinges. Also it has to be slid off the pin hinges. The box is aligned in the photo as the makers intended, hinge pins pointing upward. But how is it installed in real life?

Z.

Only for you Chris, to solve the mystery I have searched for another photo to put everything into context. You are looking at an antique operational installation. Yes, I know what you are thinking.

But, what is the earthing arrangement?

Presenting as TN-S - is this site large enough for a private or at least dedicated transformer so there will not be unexpected changes to Zs and PSSC? The singles running the current transformers look a bit unrestrained  and near the edges of  that duct with the lid held on by cable tie, so I hope the earth wiring for that is going to win a race with the supply  fuse.

Compared the phase conductors all the green/yelllow and some of the black looks a bit thin.

Given all the outbounds seem to be single phases 3 boards might have been expected, or are there some 3 phase sub mains going out ?

Certainly one where you would not start from here nowadays.

Mike.

The incoming is 400 Volt from overheads. There is no dedicated site transformer. The main earthing is provided by a single large conductor running downwards that disappears into a duct with the supply cable. P.N.B? I commented on the current transformer wires many months ago but was told on this forum that they are probably o.k. as they are housed in a locked room.

The three main D.N.O. fuses are rated at 400 Amps each.

All chalets are TT earthed.

Z.

Are the rewireable fuses suitable for the available fault current ? They came in three standard short circuit ratings, 1ka, 2ka, or 4ka. Those look like 1ka types and a 400 amp supply suggests a more substantial fault current than that.

That may well be the case. But perhaps the D.N.O. fuses, pre distribution board, cover that aspect of things. I know that the old stuff is not ideal. but it works andnt committee don't want an upgrade just yet. It is more likely to die of old age rust and corrosion rather than a big bang. Anyway any big bang will be contained within the substantial steel enclosure.

Z.

It may be out of shot, but are you happy it is compliant with 462.1.201, 465.2 and 465.3?  It would seem arguable that 3 separate 'main switches' (with likely only one of them switching the neutral?) may not be compliant.

Jason.

I'm not too keen on the BS 951 clamps on SWAs either...

The bottom left newish looking 3 phase fused switch with the retractable handle is the main switch. Turn it off and everything goes OFF.

I have recently been over working and under thinking. The three phase switched fuse contains three 200 Amp H.R.C. fuses. So they might compensate for the low rated breaking capacity of  the hot wire fuses in the old open fuse box.

I do no tthink that any of the switchgear in the intake room is designed or intended to be used for "emergency switching". It would take many minutes to find the key for the door and to gain access.

Z.

Agreed.

Z.