Adiabatic equation and bonding

[GaryM]

What's the earthing arrangements of the supply? Hopefully not PME?

 

[South Spark]

No it's a TNS -

 

[GaryM]

Sounds good then.

 

[telectrix]

if the 6mm main bonding shows no sign of deterioration and is proved to be connected and intact, then there is no requirement to change it. (TN-S)

 

[i=p/u]

so 6mm tn-s c

10mm tn-c-s

6mm tt

tn-s and tt can be smaller bu ysing adiabiatic what reg number gary m.. to finish me off , got book right here.. thaxnks

 

[GaryM]

Not got it with me at the moment but look at chapter 54

 

[DaveyD]

543.1.1

 

[Deleted member 26818]

Can somebody have a look at this and tell me which tree I'm barking up?

Using the Adiabatic equation to determine the required size of main bonding and therefore the size of supplementary bonding.

Ze = 0.18

PFC = 1.3 kA

Fuse type 1361 IIa

S = square root (1300 x 1300 x 0.1) /115

= 3.57

Is that right? Seems like a very low value for main earth

No nearly, but not quite.
Should be: S = √(1100 x 1100 x 0.1) / 115
= 3.03.

 

[MarkieSparkie]

For a BS1361 80A fuse:- from Table 54.2 k=143 and from Appendix 3, fig3.1 1100A @0.1s
S=√(1100[SUP]2[/SUP]x0.1)/143
S=2.43mm[SUP]2[/SUP]

 

[esc]

Good thread on the adibiatic guys. Would any of you know if actually fitting a main earthing conductor on a TT or TN-S is notifiable or not?
Cheers

 

[GaryM]

Would any of you know if actually fitting a main earthing conductor on a TT or TN-S is notifiable or not?
Cheers

Yes, that would be notifiable as it's not listed as an exception, unlike the addition or upgrade of main or supplementary bonding.

Approved Document P

 

[dellboy78]

Maybe a silly question, but what is brb??

 

[malcolmsanford]

BRB = Big Red Book the old BS 7671-2008 befroe the green one came on the 1st Amendment, is now the BGB = Big Green B..... you get my frift

 

[Deleted member 26818]

As far as I'm aware upgrading, replacing or installing earthing and bonding, is not notifiable.

 

[Engineer54]

His wording isnt clear but he mentioned main earth at the bottom of his equation so his intention was selecting the size of bonding conductors in accordance with the calculated size of his earthing conductor.

Using the Adiabatic equation to determine the required size of main bonding and therefore the size of supplementary bonding.



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Widdler is absolutely correct in what he stated, according to what the OP had posted!!

The adiabatic equation is used for sizing of the earth conductor and protective conductors only, It's ''NOT'' to be used for bonding conductors.


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