SWA armoured to a shed/workshop

[lxboy]

As long as you do it by the book I'll be fine !

Regards,

Lxboy

 

[JohnW2]

Uhm its all very interesting. One point looking at the tables that were posted I note that for 10mm SWA XPLE the CSA of the armouring is only 26mm^2 and should be 31.09 ^2 it is therefore not compliant. The supplier, that I'm thinking of using, for the SWA says that all of his cable is XLPE is this the same (a missprint maybe?). If this is the case I guess I would have to install 3 core.

As Risteard has said, this isn't really the case - and I should have warned about this when I referenced the tables in the wiki.

The 'required armouring CSA' in those tables is derived from "Table 54G", which is Table 54.7 in the current regs. That Table only exists for those who are too lazy to undertake the adiabatic equation calculation (per 543.1.3) themselves, and gives very 'conservative' figures. If you undertaken the adiabatic calculation for yourself, I'm all but certain that you'll find that the armour of 2-core 10mm XLPE SWA is fine.

Kind Regards, John

 

[ban-all-sheds]

Thanks I'm now intrigued by the adiabatic equation . Back to the books ,

Check out the last two here: //www.diynot.com/wiki/electrics:books

 

[JohnW2]

If you undertaken the adiabatic calculation for yourself, I'm all but certain that you'll find that the armour of 2-core 10mm XLPE SWA is fine.

If, for the purpose of an example, one considers a fault current of 500A and a corresponding MCB operation time of 5 seconds (very pessimistic), then for steel armour (thermosetting SWA at 90°, 'k'=46), the required armour CSA would be about 24.3mm², per 'the' (actually 'a') adiabatic equation.

Kind Regards, John

 

[Trefor]

If, for the purpose of an example, one considers a fault current of 500A and a corresponding MCB operation time of 5 seconds (very pessimistic), then for steel armour (thermosetting SWA at 90°, 'k'=46), the required armour CSA would be about 24.3mm², per 'the' (actually 'a') adiabatic equation.

Ok thanks!