earthing an outbuilding on main tt system supply

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alarm man

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just need a reminder(out the game a few years since moving into security systems) im running a supply to an outbuilding from the main db, outbuilding has new earth rod fitted and 4 way db with rcd protecting all circuits,the supply from main db is in swa, do i earth the supply cable at main db and isolate from outbuilding earth or earth at outbuilding and isolate at main db earth??? i just cant remember? :|

thanks

alarm man

 

steptoe

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I just know that Im going to get shot down into tiny little pieces here,

but,,,,

I personally would prob earth the swa at both ends,

it is after all the same earthing system you are using.

the provisio to this being in,

how far away from the incoming supply is the outbuilding?

thats the only concern I would have.

as far as I can see,

your not exporting an earth, it is already there,

TERRA,

all you are doing is joing up two bits of ground.

now I think I'll just sit back, relax, and wait to get tore apart. :|

 

Admin1

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I just know that Im going to get shot down into tiny little pieces here,

but,,,,

No - Really? Why? :p

 

alarm man

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from what i remember you dont connect 2 different earth potential's..+ about 60 metres from db to outbuilding...so do i earth supply at main db or outbuilding..im sort of thinking it would be main db but i need to be sure? :|

 

steptoe

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from what i remember you dont connect 2 different earth potential's..+ about 60 metres from db to outbuilding
yes, you are quite right about connecting 2 different earth potentials, but TT is TT no matter where you connect it, and you have also spiked it at shed, although this is actually irrelevant.

you cannot connect a (for example) TNC to a TT, or an IT to a TNC or TT,

but this is why I was waiting to be corrected,

I can see no reason not to connect a piece of ground to another piece of ground,

which oin effect you would be doing in connecting a TT system to another TT system.

can I also assume you are taking into account the capacity of your earthing conductor between the 2 buildings? as well as the current capacity of your lives?

if so, then I can see no reason whatsoever not to connect the 2 rods together, after all,

its simply the same as a single installation with multiple earth rods.

 

alarm man

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yes, you are quite right about connecting 2 different earth potentials, but TT is TT no matter where you connect it, and you have also spiked it at shed, although this is actually irrelevant.you cannot connect a (for example) TNC to a TT, or an IT to a TNC or TT,

but this is why I was waiting to be corrected,

I can see no reason not to connect a piece of ground to another piece of ground,

which oin effect you would be doing in connecting a TT system to another TT system.

can I also assume you are taking into account the capacity of your earthing conductor between the 2 buildings? as well as the current capacity of your lives?

if so, then I can see no reason whatsoever not to connect the 2 rods together, after all,

its simply the same as a single installation with multiple earth rods.
not sure if its a wind up or not,the potential with regards to terra is great hence the regs regarding multiple earth rods,hence why id prefer/need 2 separate earth paths

 
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Hello alarm man. I run electrical supplies to a fair few seperate buildings. The way i do it is install two core armoured cable to building, i use armouring to protect cable as earth. You need to ensure cable gland is connected to earth through earth tag at supply end. I normally put cable into seperate switchfuse for easy isolation should there be a problem at shed. Being TT at supply end i would put a time delay RCD for discrimination of RCDS. At outbuilding end i cut armouring back, the new swa strippers are ideal for this and then put tape around cable to isolate earth this is important with pme earthing. I put cable through nylon gland, install RCD consumer unit and earth rod to earth installation. I hope this might be of use

batty

 

steptoe

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Hello alarm man. I run electrical supplies to a fair few seperate buildings. The way i do it is install two core armoured cable to building, i use armouring to protect cable as earth. You need to ensure cable gland is connected to earth through earth tag at supply end. I normally put cable into seperate switchfuse for easy isolation should there be a problem at shed. Being TT at supply end i would put a time delay RCD for discrimination of RCDS. At outbuilding end i cut armouring back, the new swa strippers are ideal for this and then put tape around cable to isolate earth this is important with pme earthing. I put cable through nylon gland, install RCD consumer unit and earth rod to earth installation. I hope this might be of usebatty
BUT,,,,

its not

PME

or

TNCS

so I would say that is all a total load of ****e

only my opinion mind

but I waould really like someone to prove to me how a TERRA is not the same as a TERRA 60m away....

its the same ****ing planet...

dont care what your stoopid regs say,

TT is TT

end off....

if you choose to do it another way, then I reckon your getting yourself into a whole different kettle of fish,

and you really need to be sure of providing a secure way of disconnecting the main equipotentional bonding as well...!?

this will also carry the same fault potential on an earth fault in a TT install if you are using two different earths.

 

kme

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OK

Let me jump in here please. I love a good discussion.

The fact that you have a TT at the house; and you`re putting TT at the outbuilding means that you have effectively a (relatively) high impedance earth connection. Twice.

It would, IMHO, make sense to connect the swa armour at BOTH ends.

You do not have any issues with high current flow, as the rod impedance is sufficiently high. Hoowever, you have provided a parallel path, at approx the same resistance as the original. Therefore, you`ve halved the ground impedance; creating a better earth path. You are not going to induce a PD between different points in your earth path ( of more than negligable value), so where`s the problem?

Steptoe isn`t winding you up m8. It simply isn`t a problem. Earth it both ends.

KME

 

dougal

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OKLet me jump in here please. I love a good discussion.

The fact that you have a TT at the house; and you`re putting TT at the outbuilding means that you have effectively a (relatively) high impedance earth connection. Twice.

It would, IMHO, make sense to connect the swa armour at BOTH ends.

You do not have any issues with high current flow, as the rod impedance is sufficiently high. Hoowever, you have provided a parallel path, at approx the same resistance as the original. Therefore, you`ve halved the ground impedance; creating a better earth path. You are not going to induce a PD between different points in your earth path ( of more than negligable value), so where`s the problem?

Steptoe isn`t winding you up m8. It simply isn`t a problem. Earth it both ends.

KME
I agree using two earth rods on a tt system instead of one has got to be a good thing no matter where they are located. as long as you are going TT to TT. you are basically having one system instead of two.

craig

 

ABC Technical

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Steptoe is not daft or a wind up merchant, he speaka da troof. Terra is terra simple really.

 

Nicky Tesla

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Steptoe are you at it again talking a load of sh............wait a minute, this time, with both ends TT, I actually find myself agreeing with you.

Wonders never cease:^O

 

SPECIAL LOCATION

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Steptoe are you at it again talking a load of sh............wait a minute, this time, with both ends TT, I actually find myself agreeing with you.Wonders never cease:^O
Ohhhhhh blimey!!! :(

that's bad!!! :eek: :O:O

Nickey agrees with steptoe.......

I reckon thats a warning sign.....

bit like the tide going really far out before a tsunami!!

somthin bad's gona come round the corner....

wots more it'll probably crash the server.!!!

Welshy get ready to switch the back up server over..

pull the UPS' units out of your shed we may need more power!!!

Beware of tomorrow's threads...???? :^O :^O:^O

evnin Mr T'! :)

 

kme

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Steptoe are you at it again talking a load of sh............wait a minute, this time, with both ends TT, I actually find myself agreeing with you.Wonders never cease:^O
Ohhhhhh blimey!!! :( that's bad!!! :eek: :O:O

Nickey agrees with steptoe.......

I reckon thats a warning sign.....

bit like the tide going really far out before a tsunami!!

somthin bad's gona come round the corner....

wots more it'll probably crash the server.!!!

Welshy get ready to switch the back up server over..

pull the UPS' units out of your shed we may need more power!!!

Beware of tomorrow's threads...???? :^O :^O:^O

evnin Mr T'! :)
At last! I knew the day would come!

Mr Tesla, sir. 1 Scoob for you. Don`t eat it all at once m8!!!

It would appear that the "old hands" are in agreeance on this one???

:) Lovin` it!!!

 

steptoe

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Steptoe are you at it again talking a load of sh............wait a minute, this time, with both ends TT, I actually find myself agreeing with you.Wonders never cease:^O
I knew I had got it all wrong......

:^O :^O:^O

thanks Nicky, :D

 

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