CCC Ring or Radial

[dizz]

If I calculate the CCC for a 2.5mm cable to be X amps using a particular installation method, is it true that if I use that cable with that method as a ring, then the CCC of that cable in the ring is 2X amps? (as assuming even load the current is split down each side of the ring). e.g. if the calculated CCC of the cable is 27A, I could either install the cable as a radial with a 20A MCB, or I could install it as a ring with a 32A MCB, even though the CCC is 27A, because actually each side of the ring could take 27A = 54A total load? Is that right?

 

[Taylortwocities]

Not quite.

The loads on the ring will not be equally balanced. Its very likely that the diswasher, washing machine and tumble dryer will all be at one point on the ring so your max current will all be down there.

That's why the fuse is max 32amps.

Why do you ask these questions, grasshopper?

 

[JohnW2]

If I calculate the CCC for a 2.5mm cable to be X amps using a particular installation method, is it true that if I use that cable with that method as a ring, then the CCC of that cable in the ring is 2X amps? (as assuming even load the current is split down each side of the ring). e.g. if the calculated CCC of the cable is 27A, I could either install the cable as a radial with a 20A MCB, or I could install it as a ring with a 32A MCB, even though the CCC is 27A, because actually each side of the ring could take 27A = 54A total load? Is that right?

Your conclusions for your example are correct, but cannot necessarily be extrapolated to other situations. The regulations specifically require that for a ring final circuit with a 32A MCB, the cable must have a CSA of at least 2.5mm² and a CCC (with the installation method used) of at least 20A (but do not give figures for ring final circuits under any other circumstances). For a 20A radial circuit, the CCC obviously must also be at least 20A.

Kind Regards, John.