What does the incoming cable look like if the earthing is TNS?

[HappyHippyDad]

I never get to see the incoming cable supplying power to a domestic property.

Does a TNCS earthing system usually have an incoming cable with one core which is the line and a sheath which is the neutral?

What type of cable is used for TNS where the earth has its own conductor going back to the transformer? A cross sectional view would be great if anyone has a link?

Cheers all.

 

[Leesparkykent]

google images of concentric and split concentric cable

 

[Leesparkykent]

http://wiki.diyfaq.org.uk/images/thumb/4/41/TNSUsingPMECutout3.jpg/422px-TNSUsingPMECutout3.jpg

 

[buzzlightyear]

there you go .

 

[7029 dave]

TNS, earthing arrangement, should comprise of a matalic path normally taken from the lead sheathing of the supply cable, strapped to the earth terminal of the installation. ze measurement 0.8 ohms is the guide.

 

[7029 dave]

FYI

 

[Leesparkykent]

Only if PILC cable.

 

[Dave OCD]

Yes I've seen split concentric used many times, the lead sheathed will only be found on old buildings.

 

[telectrix]

Yes I've seen split concentric used many times, the lead sheathed will only be found on old buildings.

and will most likely outlast most new buildings. bloody chucked up for minimum cost and maximum profit. dry lining.... which pencil neck penny pincher dreamt that crap up?

 

[Midwest]

I repeat; following query over issue with domestic supply, DNO engineer attended, and in conversation said 'most domestic supplies TN-S will have been turned into PME (his words) somewhere out in the road etc, 'cos of repairs.

Life's like a box of chocolates, you never know what you'll gonna get.

 

[Midwest]

and will most likely outlast most new buildings. bloody chucked up for minimum cost and maximum profit. dry lining.... which pencil neck penny pincher dreamt that crap up?

Arrgh yes, looking back to the past of straw walls and lathe & horse hair plaster

 

[HappyHippyDad]

Arh OK.. so concentric cable for TN-C-S and split concentric for TN-S!
Cheers Lee

 

[Midwest]

Arh OK.. so concentric cable for TN-C-S and split concentric for TN-S!
Cheers Lee

Who knows!

 

[telectrix]

Arrgh yes, looking back to the past of straw walls and lathe & horse hair plaster

lath & horsehair has proven itself by lasting hundreds of years. still be around when all this gyproc crap has been dumped in the oceans.

 

[Midwest]

lath & horsehair has proven itself by lasting hundreds of years. still be around when all this gyproc crap has been dumped in the oceans.

Where you been, you can't even put it in landfill now.

 

[static zap]

lath & horsehair has proven itself by lasting hundreds of years......

Still sure we can do better than Thatching quaint cottages , that passing lorries damage / birds love for nesting.
(Probably council / preservation order related ..stupidity)

 

[Lucien Nunes]

Does a TNCS earthing system usually have an incoming cable with one core which is the line and a sheath which is the neutral?

Often this will be a concentric cable, so the inner conductor is L, and the outer is CNE (it's not the sheath!)

What type of cable is used for TNS where the earth has its own conductor going back to the transformer?

Paper-insulated lead covered service cables: Two cores L & N and the lead sheath as earth. This time it is properly called the sheath, i.e. it is the covering that seals and encloses the cable. There may be armour etc over the top but the cable itself is enclosed in the lead, which also serves for earthing.

Split-concentric service cables: One core L, insulated strands of the outer as N, bare strands of the outer as E.

But as mentioned, a split-con may be functioning as TN-C-S if the N and E cores are linked at the service joint.

 

[HappyHippyDad]

Thanks Lucien, that was really well explained. I dont know why I had rated it 'old', I dont even know what that means! Sorry