Tt or tncs

[carson]

Just been to carry out a pir on a flat & the supply cable comes in line & neutral only & goes directly to the meter it then comes out of the meter to henley blocks which then supply the 2 consumer units, each consumer unit has an earth conductor connected into the henley block for the neutrals. is this wrong as i think this would tt to tncs conversion carried out on the consumer side of the supply

 

[malcolmsanford]

It sounds very wrong, a picture might help.

 

[telectrix]

wrong and possibly dangerous.

 

[IQ Electrical]

It sounds like a nasty DIY PME conversion.

When you say the supply goes directly to the meter, do you mean it's unfused?

 

[carson]

I'm sorry lads maybe i should have explained it a bit better, this is a second floor flat the main 3 phase supply comes in on the ground floor to an understair cupboard it is then split up & fused & the seperate cables go up the service ducts to the individual flats, this is all done as you would expect with a 3phase & neutral supply at the origin with a seperate earth conductor coming into the main cut out enclosure which is then linked to the neutral. To me this is a typical tncs supply but after the supply cable comes into the flat i have the problem detailed in the previous post.

 

[malcolmsanford]

Well by the sounds of things and before we even go down the BS 7671-2008 road, what you have described is very much against the ESQCR-2002 statutory document and regulation 8(4) let alone our regs..

I can't remember the old Electricity Supply regulations one but a bit I do remember is that they also banned the use of TN-C within the installation.

So if that is what you have I think it may need a little remedial work.

 

[carson]

Thanks for the replies lads the wiring installation within the flat is one of the worst i've seen e.g loop in lighting using only 2 t&e using the cpc as live conductors, no main or supplementary bonding etc etc. I've just never seen a tncs supply converted to tt by the supplier then converted back to tncs by the original installer.

 

[malcolmsanford]

Why are you thinking it is a TT, is there an earth electrode also knocking about.

You seem to have by your description a TN-C and as I just said you can't have them within an installation unless under certain very strict conditions and is rare to say the least.