Is this correct ??

[Sav]

Hi guys,
Just a quickie for you to confirm if possible.

Father in law just finished his office/storage area brick built area at the end of the garden (approx 40 meters away from house).
The main supply to the house is a TN-S.
I run a 16mm swa from inside the house to the office ( clipped outside on the lower wall and then into the ground, covered etc as per regs).
Also, I run along with it another 16mm earth.
Inside the house the swa is connected to 60amp isolator, which in turn has 25mm tails into the henley blocks that also have 25mm tails for supplying the house c/unit.
The 16mm earth is connected to the MET along with other earths.
The office building in the garden has a dual rcd board with 63amp main switch.
Is this ok as far as you can "see", or have I missed anything else out ??

I used 16mm swa due to length of run, but Could I have used a smaller earth along with it (adiabatic equation) ??

Thanks again guys for all your help,
Sav

 

[Sparky Ninja]

why is the earth run seperatley, as opposed to a 3 core swa?

 

[Sav]

I have used a 3 core swa, but a collegue of mine said that you have to run a min size 16mm additional earth with it??? I couldn't find that anywhere in the regs and I did question him, but he said thats the way his boss ( apparently top sparks) does it all the time. Only with 10mm swa you dont need to run a separate earth ?? VERY confused, I thought the way I had it, 3 core 16mm swa, was fine.

Thanks again for taking the time to reply.
Sav

 

[wattsup]

3-core swa would be fine

 

[Spudnik]

3 core SWA is fine.

You only need a separate 10mm if there are services in the outbuilding, and even then you probably wouldnt need it with 16mm 3 core.

Normally, if that is the case, then its easier and more cost effective to install a spike to the outbuilding and bond everything there.

 

[Sav]

Hi Jason,
Do you mean services as in gas water etc???
Please clarify, so that I can throttle my mate who said my work was "crap" !!!
Thatnks mate
Sav

 

[Des 56]

The 16mm swa earth core can perform the 2 functions of protective conductor and bonding conductor
If it was smaller then maybe a seperate 10mm to bond the services

I recently found out that the armouring alone can perform this function if the calculations allow,so the earth core and the armorings will be well above whats required

 

[Sav]

Hi Des,
Thanks for the reply.
As the swa is going into the consumer unit in the new building (the consumer unit is plastic casing), I terminated the swa using glands etc and I obviously put the earth into the earth bar inside the c/unit.
Do I need to earth the actual metal sheath as well ??? I dont think so, but do you think thats ok as I have it.
Sorry to bombard you with these questions, but I am hoping to show the Elecsa assesor this job, so any input you guys give is great.
Its good to know that you guys are around.

Thanks again to all of you,
Sav

 

[pennywise]

Thats what the banjo is for. Nut and bolt it with a fly lead to the main earth bar.

 

[beaver74]

Hi Des,
Thanks for the reply.
As the swa is going into the consumer unit in the new building (the consumer unit is plastic casing), I terminated the swa using glands etc and I obviously put the earth into the earth bar inside the c/unit.
Do I need to earth the actual metal sheath as well ??? I dont think so, but do you think thats ok as I have it.
Sorry to bombard you with these questions, but I am hoping to show the Elecsa assesor this job, so any input you guys give is great.
Its good to know that you guys are around.

Thanks again to all of you,
Sav

yes the sheath needs earthing

 

[Guest123]

Hi.

The chap is sort of right in what he is saying as the armour of a 16mm 2 core PVC/XLPE SWA is not big enough by itself to serve as a CPC, which is why you would need to run a seperate one.

As you have a 3 core and as it's single phase the 3rd core by itself is more than enough, no need for a seperate one.

Sounds like a bit of confusion as to number of cores you had.

 

[Sav]

Hi again,
Thats great,
I will fly lead the sheath 1st thing in the morning.
Will the assesor knock off points as such, for the additional earth that I run, or do you think thats ok?

lol
Sav

 

[Guest123]

He may ask why you did it, but wont mark you down for it.

 

[AEC]

Hi Des,
Thanks for the reply.
As the swa is going into the consumer unit in the new building (the consumer unit is plastic casing), I terminated the swa using glands etc and I obviously put the earth into the earth bar inside the c/unit.
Do I need to earth the actual metal sheath as well ??? I dont think so, but do you think thats ok as I have it.
Sorry to bombard you with these questions, but I am hoping to show the Elecsa assesor this job, so any input you guys give is great.
Its good to know that you guys are around.

Thanks again to all of you,
Sav

Think you should start again as your design is wrong.

3 core SWA was the answer. Yes you earth the metel sheath of the SWA as you could end up with a different potential between them in the event of a fault.

 

[Des 56]

The armouring of an swa is primarilly mechanical protection ,but as peenywise stated it is common and good practice to do so,