TNC Earthing system.

[kung]

Hi Guys

Just a quick something for others to watch out for ! on checking the earthing system out at first glance i have 2 swa cables entering my house 1 for line 1 for neutral ! strange it isnt one cable with both in ! still there you go ! anyway both cables on entering 1-neutral block and the other the cutout fuse carrier both cables have earth clamps with cpc from both clamps going into an earth block before the cpc goes from here to CU ! from what i was taught and what is now on 17th ed certs theres tns/tncs/tt ! so this would be tns ! wrong ! from an old 16th ed cert its a tnc system ! on checking the big red book it does exist ! so on phoning the DNO they told me that they want all earthing systems to be tncs/pme eventually so im now down for a cutout change (4-6wks) told them im ex S.E.B. Meter recert and related to jointers manager so hope get it done next wk ! Just goes to show how easy it is to mistake an earthing system !

Regards

Kung.

 

[Doc Hudson]

Just out of curiosity Kung, did you take any photograph you could put on the forum, it may be helpful to some of the others still doing college etc.. to see some of the more obscure real life supply examples?

Doc H.

 

[green-hornet]

I would love a photo of that.

I have never seen any supply provided like your description.

Often if two cables enter your property its normally a loop out that you can see, but from your description this is not the case (SWA) ?

 

[ianmacd]

Is it possible someone has "extended" it? Has a building moved/been rebuilt at all?

 

[kung]

Hi guys i could do a pic but how do i get it on here ? tried on another forum but couldnt !

will take a pic brb.

 

[a1]

Hi guys i could do a pic but how do i get it on here ? tried on another forum but couldnt !will take a pic brb.

Here we go my friend:

http://www.talk.electricianforum.co.uk/showthread.php?t=627

I look forward to seeing them.

 

[kung]

Had to put the links on both of my messages on this post also for the collage boys here is my fuse when i was working for SEB ! its a 12/7.2kv 25ka fuse from a substation ! just right for stuborn customers !

 

[Doc Hudson]

Hi guys i could do a pic but how do i get it on here ? tried on another forum but couldnt !will take a pic brb.

Well it appears you have cracked the adding a photo, because I can see all of those. Thank you for adding them, Kung. As they say, a picture is worth 1000 words and it is quite a "Large" fuse that one!!

Doc H.

 

[Riggy]

Am I missing something here, it looks like a tns supply with a loop out to another cut out, probably next door?

 

[kung]

Am I missing something here, it looks like a tns supply with a loop out to another cut out, probably next door?

i thought the same though ! with regards to loop NOPE ive removed cutout covers (got permit to opp on multi ph cutouts on SEB Course) and its 1xline going into fuse and 1xneutral going into the neutral block !

 

[msb2003]

I would guess it's NOT a TNC system as you can only use that under special circumstances and anyway the earth is seperate from the point shown so cannot be TNC.

I think the previous certification was wrong and should have read TNS.

Looks to me like the cable sheath is providing the earth (TNS) Are you sure they are SWA's? as from the photos they look like lead covered distribution cables, probably 1 in 1 out as Riggy states.

 

[kung]

I would guess it's NOT a TNC system as you can only use that under special circumstances and anyway the earth is seperate from the point shown so cannot be TNC.I think the previous certification was wrong and should have read TNS.

Looks to me like the cable sheath is providing the earth (TNS) Are you sure they are SWA's? as from the photos they look like lead covered distribution cables, probably 1 in 1 out as Riggy states.

Just goes to show the 16th ed cert in 96 was done by a jib grade spark who states its TNC !

Now im confused ! as ive said id say TNS the jib spark says TNC the DNO say its either TNCS or TNS when ive explained the sparks choice of TNC all they say is were not at liberty to supply an earth (typical answer as they SHOULD know what they supplied on file !) ANYWAY they put me down for the cutout change to PME so TNCS ! so earth spike is needed for garage as metal frame dont know if it would have been TNS if it would still need the spike ? the SWA for garage feed leaves house and goes 6ft under ground(concrete) and enters garage and goes 3ft to CU.

 

[green-hornet]

The photo's show the supply to be TNS but be carefull as I am sure you are.

If there is an internal link from the nuetral to the met then you have a problem.

I have seen a cutout change where they changed the earthing arrangements from TNS to TNC-S but they removed any clamps to the lead sheath from the in comming supply cable.

The cables in the picture are not swa as msb2003 has said they are the normal TNS supply cables which are made up by wrapping paper bitumin and steel bands around a lead sheath with insulated cables within.

 

[a1]

TNS Attachments. Loop out to my next door neighbour...

Two things Before you Look at them...

1). That is the old colour of the room that they're in (in a cupboard).

2). No I did NOT remove the seals. Must have been the fairy when it was re-wired on behalf of the council.

 

[WarrenG]

Nice Pics of the loop in, apparently this was quite common by some DNO's to save on cable runs.

 

[batty]

TNS Attachments. Loop out to my next door neighbour...Two things Before you Look at them...

1). That is the old colour of the room that they're in (in a cupboard).

2). No I did NOT remove the seals. Must have been the fairy when it was re-wired on behalf of the council.

Is that an asbestos board Mr Admin. I did one last year overhead cable had been replaced so new head had been fitted, contractors did not even fix head to board it was hanging. I suppose health and safety would not allow them to drill it. My mate who normally does my jobs was to busy so I changed it myself.

Batty

 

[mayfield]

Don't laugh, but unfortunately some sparks don't know the differance between TNC/S, TNS and TT systems, TNC systems are not normally used here in the uk so the jib spark could have just been mistaken.

Looking at the pictures i would definately say TNS, and like others would have said the supply is looped to another property. This seems very strange!

 

[Apache]

Don't laugh, but unfortunately some sparks don't know the differance between TNC/S, TNS and TT systems, TNC systems are not normally used here in the uk so the jib spark could have just been mistaken.Looking at the pictures i would definately say TNS, and like others would have said the supply is looped to another property. This seems very strange!

is the rod not a dead giveaway with TT?

:|

 

[kung]

Thanks guys thought i was going mad saw it and thought TNS the TNC threw me as ive never seen one before !

Regards

Kung.

 

[Evans Electric]

Surely Kung's photo shows the usual 2 core PILSSWA incommer with a loop feed to next door . Earthing TNS. Cable sheath.

Deke