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Following on from another thread I have just replied to it got me thinking about ring circuits and reference methods.
Appendix 15 shows a ring on a 32A MCB. It does begin with a get out clause regarding thermal effects but it just points you Chapter 42 which deals with fire.
If for example we had a ring which was completely routed in reference method 103 what MCB would we choose? We know that the CCC of 1 x 2.5mm cable is 13.5A but how does this tell us exactly what size MCB to use for the ring?
There must be a simple equation to use based on the CCC of 2 x 2.5mm cables used as a ring, to find out the MCB required?
Appendix 15 shows a ring on a 32A MCB. It does begin with a get out clause regarding thermal effects but it just points you Chapter 42 which deals with fire.
If for example we had a ring which was completely routed in reference method 103 what MCB would we choose? We know that the CCC of 1 x 2.5mm cable is 13.5A but how does this tell us exactly what size MCB to use for the ring?
There must be a simple equation to use based on the CCC of 2 x 2.5mm cables used as a ring, to find out the MCB required?