Zone 1.

How does the general situation measure up to 701.415.2 (iv) to (vi)?

  - Andy.

AJJewsbury: 
 

How does the general situation measure up to 701.415.2 (iv) to (vi)?

  - Andy.

Well, currently the bathroom lighting circuit is protected by a 100mA R.C.D. until it is renewed.

Z.

What is connected to the tub? If it's all plastic pipes, in and out; I don't think that you need to worry because it isn't an extraneous CP.

In fact, I don't think that the material of the tub matters: it's the taps which count.

Chris Pearson: 
 

What is connected to the tub? If it's all plastic pipes, in and out; I don't think that you need to worry because it isn't an extraneous CP.

In fact, I don't think that the material of the tub matters: it's the taps which count.

Yes Chris, metal taps and metal supply pipes to the bath taps.

Also, I am beginning to think that the supply may be P.N.B. rather than TN-S, as a 16mm2 green and yellow single disappears into the ground at the meter position. The three phase underground supply cable provides just a single phase and neutral at present to a grey three phase head. The Ze reading does seem very low for a rural village location.

Edit. Add. Or we could have a P.M.E. supply here but the N-E link is external to the property.

Z.

Also, I am beginning to think that the supply may be P.N.B. rather than TN-S, as a 16mm2 green and yellow single disappears into the ground at the meter position.

It could be both TN-S and PNB - especially if it's a single consumer on a transformer. Ze would be the entire loop through the transformer regardless - the position of the N-PE link or indeed the electrode wouldn't make much difference to that.

The DNO probably want you to regard it as PME in any event - just to allow them to make future alterations without having to worry about consumer's internal arrangements.

  - Andy.

AJJewsbury: 
 

Also, I am beginning to think that the supply may be P.N.B. rather than TN-S, as a 16mm2 green and yellow single disappears into the ground at the meter position.

It could be both TN-S and PNB - especially if it's a single consumer on a transformer. Ze would be the entire loop through the transformer regardless - the position of the N-PE link or indeed the electrode wouldn't make much difference to that.

The DNO probably want you to regard it as PME in any event - just to allow them to make future alterations without having to worry about consumer's internal arrangements.

  - Andy.

The installation is an old thatched cottage, previously a pub with many houses nearby, so not isolated. The local transformer, which I have not seen, was renewed a few years ago after a driver crashed into the old one and severely damaged it. There is no P.M.E. sticker at the premises, and the neutral block is solely that.

Z.

I am a little confused regarding the earthing arrangement. If TN, how is the MET connected to the service cable?

Depending upon the service head, you wouldn't know whether the N-E link has been made inside it, but if there is a link (there or nearby) PSSC and PEFC should be very similar.

I agree that a Ze of < 1 ohm is unlikely to be TT.

It seems that not all rural supplies follow the rules.

Chris Pearson: 
 

I am a little confused regarding the earthing arrangement. If TN, how is the MET connected to the service cable?

Depending upon the service head, you wouldn't know whether the N-E link has been made inside it, but if there is a link (there or nearby) PSSC and PEFC should be very similar.

I agree that a Ze of < 1 ohm is unlikely to be TT.

It seems that not all rural supplies follow the rules.

There is no green and yellow earthing conductor coming from the service head Chris. The 16.0mm2 green and yellow single comes up from the ground as a single cable. Where it is connected I do not know.

Z.

It seems that not all rural supplies follow the rules.

Well indeed. Sounds like TNS in some form (pure or PNB) 1 ohm is probably a lower electrode resistance than the pole pig alone, let alone that plus any house electrode in series.

There is always an  NE ink that is external.. The great unknown is there may be more than one .

That GY presumably picks up the cable outer at a buried joint.

How old is the 3 phase cable - old enough to be PILC ? maybe TNS

If its consac treat as PME.

Mike

mapj1: 
 

It seems that not all rural supplies follow the rules.

Well indeed. Sounds like TNS in some form (pure or PNB) 1 ohm is probably a lower electrode resistance than the pole pig alone

How old is the 3 phase cable - old enough to be PILC ? maybe TNS

If its consac treat as PME.

Mike

The incoming cable is not P.I.L.C. it is plastic covered. The 3 phase head is grey in colour L1, L2 L3 and N only.

This property is located in the Norfolk Broads, and the water table is perhaps two for three feet below the ground surface.

An aged post by BOD ref. CONSAC..

Probably due to the problems with the outer sheath being damaged (when was the last time you saw it installed with 150 mm of sand around it?) by the typical backfill and the Al sheath forming what looked look a mass of aluminium "rust" (ask any LandRover owner

) that eventually causes loss of Neutral/Earth.

Z.