Is this TN-S?

[oneofthedamned]

Just a quick one. Need to do i minor works cert for a job and this was the earthing arrangement. Is this TN-S. Usually the earth is attached to the outer armour. It has been changed from a TT system at some point as there is an earth spike outside with a cable going through the wall which has been cut off inside.

Thanks in advance

OOTD

 

[steptoe]

what is your Ze compared to your L-N resistance and the PFC.

 

[sparkytim]

Looks like TNS as 3rd core of incomer used as Earth.

Just a strange one as this looks like normal 3 Cre SWA not usually used by DNOs, Is it an interconnector from another Supply point, or coming in from Road direct?

 

[oneofthedamned]

Sorry Steps, did not do Ze. Only did Zs, IR and timed RCD. It was only moving a couple of sockets so did not do full tests. It was just the earthing arrangement that threw me. Zs on sockets 0.80

---------- AUTO MERGE Post added at 11:54 ---------- Previous post was at 11:29 ----------

The cable comes in underground and goes up from the service head to the meter. I don,t know where it comes in from. There are no other distribution boards it could be fed from.

 

[tom1]

did you do r1 r2 or just r2

if r1 r2 you could get a rough indication of ze

 

[batty]

Just put it down as TNS its not TNC-S because the neutral is seperate to the earth on the incoming cable. It can't be TT because the DNO are supplying the earth. I really would not worry to much who is going to check anyway. Looks like a new cable has been brought in recently they have used a three phase cable but as only one phase is being used they have made use of the l3 as the earth which probably goes to the lead sheath underground.

 

[Sidewinder]

The DNO side will almost certainly be PME where this cable is jointed to the local mains.

 

[Andy™]

that does not look like a DNO job. the only thing i can see that may be genuine is the RYB colour circle's above the fuse holders. maybe an old ditched TP supply, with SP via SWA added? also no seals on fuses

maybe worth contacting DNO to find out what should be there compared to what is

 

[Sidewinder]

They looked like RWB to me not RYB! So they looked even older.

Yes I agree it does not look like a DNO cable as they are normally waveform & they don't normally waste copper like this!!!

 

[a1]

They looked like RWB to me not RYB!

I was about to say the same thing, Sidewinder.

 

[Andy™]

They looked like RWB to me not RYB!

i must be going colour blind!

 

[Sidewinder]

Sorry Andy, after zooming in still looks like RWB to me.

 

[batty]

So is there a meter?

 

[oneofthedamned]

Thanks for the replies. I think I'm going with TN-S. Yes Batty there is a meter

 

[Sidewinder]

BTW,

So would I, but I would try to clarify the supply cable or note that it appears NON standard.

Just to cover my a**e.

 

[Robin Spark]

So are you guys suggesting to the OP that this might be a job not officially done by the DNO as there are no seals and non standard cable used by them?

Can you enlighten me guys please, was RWB used before RYB cos I have never heard of this before?

Also thinking that the SWA hasnt got the armour earthed, hope somebody doesnt dig into by accident!

 

[batty]

I would not think this has been done by anybody other than DNO or there sub contractors. Remember DNO contract a lot of work out these days well EDF do I have just had my cut out changed and this was done by Morrisons and they don't use the same materials that EDF use so its a good chance it was done by a sub contractor and may be that was the cable they had on the van or they were supplied with. To me there is nothing wrong with that supply I would put it down as TNS and be done with it at the end of the day you have not done the install so you would not be liable if anything were to go wrong and why should it anyway.

 

[Sidewinder]

OK down here WPD do all their own works into properties.

Yes RWB was before RYB.

Back in the late 60's IIRC.

 

[Badger]

I would not think this has been done by anybody other than DNO or there sub contractors. Remember DNO contract a lot of work out these days well EDF do I have just had my cut out changed and this was done by Morrisons and they don't use the same materials that EDF use so its a good chance it was done by a sub contractor and may be that was the cable they had on the van or they were supplied with. To me there is nothing wrong with that supply I would put it down as TNS and be done with it at the end of the day you have not done the install so you would not be liable if anything were to go wrong and why should it anyway.

well i hope they didnt install you a wet lettuce for a meter :^O :coat morrisons safeways :coat :^O :^O

 

[oneofthedamned]

Thanks for all the replies. Helpful as ever. TN-S it is with a note in the remarks ref. connection anomaly.