First time doing an EICR on a flat

[Mark Adamson]

Hi all
Done a EICR on a flat which had the link fuse in the service head .. had an earth wire coming off the orange cable to an earth block.
Carried out a ZE test got 14 ohms and got same reading when did ZS on the board (yes did disconnect earth for ZE) .. the main earth is wired into the service block .. I’m guessing the orange cable is going to a main fuse in the plant room and is armoured ..

 

[snowhead]

The orange cable will go to the main incomer into a Ryfield or similar fused board.
The cable is split concentric, (Google it if you're not familiar) not SWA /Armoured.

 

[Mark Adamson]

The orange cable will go to the main incomer into a Ryfield or similar fused board.
The cable is split concentric, (Google it if you're not familiar) not SWA /Armoured.

Thanks for your reply have done mostly commercial and houses .. was baffled why the ze and as we’re same value .. would I be picking up parallel earths on this setup ?

 

[timhoward]

It looks like the main earth into the consumer unit is connected to the service head.
If the Ze is that high it feels like there is no Neutral - Earth link in that head.
Did you try a Ze to that MET?

 

[buzzlightyear]

I’m guessing the orange cable is going to a main fuse in the plant room and is armoured ..

More like micc.

 

[Mark Adamson]

It looks like the main earth into the consumer unit is connected to the service head.
If the Ze is that high it feels like there is no Neutral - Earth link in that head.
Did you try a Ze to that MET?

No I didn’t i am going back to replace the cooker switch this week and will try and see what the reading is .. thanks in advance

 

[westward10]

Could be MICC, could be a concentric cable probably split concentric and the bare earth cores are just wrapped in tape. Orange split concentric often denote SNE systems.

 

[buzzlightyear]

Have they made that cut out to Tncs or is it a a TNS, by looking at the earth met.

 

[westward10]

Have they made that cut out to Tncs or is it a a TNS, by looking at the earth met.

Does seem odd the separate earth block is not used and the earthing conductor goes to the head.

 

[littlespark]

If it was MICC , there would (should) be a proper pot on the end.
I’m going with split concentric.

Depending on age of the building, the water pipes could be metal, bonded to the MET, and also bonded at the main incomer, and in every other flat

 

[Mark Adamson]

Does seem odd the separate earth block is not used and the earthing conductor goes to the head.

And it all been sealed so

Have they made that cut out to Tncs or is it a a TNS, by looking at the earth met.

I’m not sure as it has been sealed .. didn’t want to break the seals
Will do a Ze from the MET block and see if I get any different reading as so far all the max ef are just over the limit (gn3) table type B 32 1.1 max r1 / r2 1.0 ze.14

 

[timhoward]

And it all been sealed so

I’m not sure as it has been sealed .. didn’t want to break the seals
Will do a Ze from the MET block and see if I get any different reading as so far all the max ef are just over the limit (gn3) table type B 32 1.1 max r1 / r2 1.0 ze.14

You said Ze and Zs@DB were 14 ohms in first post. Which is why I questioned whether there is actually an earth at all (and whether N-E link isn’t there, and if the intent was for main earth to connect to MET)

If that is true your final circuit loop tests are only anywhere near reasonable-ish due to parallel paths.

Maybe it’s me that’s misunderstanding the setup as no else seems concerned!

 

[westward10]

I think it is a typo but you are correct questioning 14 ohm, he has .14 ohm in #11.

 

[buzzlightyear]

If doing a Ze line /earth, what tester are you using.

 

[davesparks]

The orange cable is a split concentric cable providing an SNE (TNS) service, the orange outer sheath denotes that it is LSF cable.

The consumers earth should be connected into the earth block provided, not into the service head. I would guess that an installer misunderstood the type of supply and assumed it was TNCS.
As we all know they rather quickly stopped using TNCS for the distribution within a block of flats as it leads to diverted neutral currents flowing through structural steelwork and other services causing all sorts of problems.