Hi could someone help me please. I'm at college doing 2330 level 3. I'm currently doing inspection and testing. I need to know where I find my (r1+r2) on my sub main. Which is powering a double socket and a light. Thanks
Just for your info mate, as you are in training.
A sub main is exactly the same as any other radial circuit for the purposes of inspection and test, so the test methods are identical.
Where a sub main differs from a radial circuit, is in its application. A circuit which originates at a Consumer unit or similar and goes into the installation to supply lighting, sockets, cookers etc, is known as a radial circuit.
A circuit which originates at a Consumer unit or similar, and then goes to another consumer unit, like house to garage, then this is still wired as a radial circuit, but it is known as a Distribution Circuit (aka sub main).
The two need to be differentiated, because depending on certain things like protective devices, you can have disconnection times that are different on a distribution circuit from a radial circuit.
I will let you find the difference between a ring main, and a ring final circuit for yourself.
Cheers............Howard
