Ring main question

[cox377]

Hello guys, for a standard ring main in a residential property, do you guys run twin or single 20mm PVC conduits upto the boxes for the 2.5mm T&E? As in do you run a single cable per conduit or do you double up?

Thanks

CoXen

 

[ricicle]

Why are you using conduit for twin and earth and what about the rest of the runs ?

 

[riveralt]

Hello guys, for a standard ring main in a residential property, do you guys run twin or single 20mm PVC conduits upto the boxes for the 2.5mm T&E? As in do you run a single cable per conduit or do you double up?

Thanks

CoXen

Don't normally run pvc conduit in 'domestic' property - is that different to residential property? Or are we talking about the same thing?

You will have to determine the cable factors, the length of the run and the number of bends for single cores. See OSG Appendix 5.
For other types of cables you have to ensure that the space factor does not exceed 45% of the net internal cross sections area.

Better to use Reference method C.

 

[DetlefSchmitz]

For a ring final the cable has to be rated at 20A. I seem to remember doing the calculations and finding that 2.5mm² twin and earth grouped 2 to a conduit came out slightly lower than 20A, so strictly speaking it needs two pieces of conduit.

 

[cox377]

Why are you using conduit for twin and earth and what about the rest of the runs ?

Thanks for coming back to me guys.

The conduit would be used to run the cable up to the boxes?

Domestic yes or residential