Adibatic equation for 6mm earth

[Des 56]

since when did the adiabitic account for main bond sizes......

Allready aknowleged

 

[professional]

Hi mate.

Think you might have been mis-informed there. No calculation is needed for main equipotential bonding conductors just select from the relaevant table in ol' red. 10mm earth is the smallest size to use upto 35mm tails, then 16, 25, 35 and 50mm. The largest size you would ever need to go upto for a bonding conductor is 50mm for tails of 150mm or over.

The adiabatic equation is only used to initially size/confirm the size of the main/circuit protective conductors.

The IEE regs specify the size of main bonding conductors for NEW installations - if you were (for e.g.) carrying out a PIR on an installation, the adiabatic equation can be used to ascertain if the EXISTING bonding is adequate for it`s intended pupose, it may not be necessary to upgrade it unless further load/new circuit(s) are to be added.

 

[Guest123]

Would you care to provide an example showing how you would use the adiabatic to size a bonding conductor.

Cheers.

 

[johnnyb]

I would be interested in seeing that as well ?

 

[Guest123]

Yes it was
It seemed appropriate
Only wish I could type so proficiently

It was absolutely appropriate Des. A good example of how to use the adiabatic.

 

[professional]

I would be interested in seeing that as well ?

Based on your prospective fault current and the size of the main fuse, it is feasible for a bonding conductor of 6mm squared to be adequate to carry the full fault current of the installation up to the point that the main fuse blows WITHOUT DAMAGE. Clearly this is only appropriate on existing installations as the OSG now tells us what we should do without us having to use our brains.