Following your reasoning the CPD for a ring circuit should not be 32A, it should be the maximum current that could be drawn from all the sockets, with cable size to match! The point is that 32A protects the CABLE sufficiently, even if I plug in 50A of load. This is exactly the same as these showers.
Not exactly the same - if done properly a ring is arranged such that it will adequately serve all the expected loads (as distinct from the number of sockets) without overloading (taking diversity into account) - in the old days it was done by floor area of course, now we're expected to use a bit more nouce, but all the same it shouldn't be expected to suffer small overloads of long duration. It's well know that overload protection often doesn't perform well in that situation - hence the warning of regulation 433.1.
Following your reasoning the CPD for a ring circuit should not be 32A, it should be the maximum current that could be drawn from all the sockets, with cable size to match! The point is that 32A protects the CABLE sufficiently, even if I plug in 50A of load. This is exactly the same as these showers.
Not exactly the same - if done properly a ring is arranged such that it will adequately serve all the expected loads (as distinct from the number of sockets) without overloading (taking diversity into account) - in the old days it was done by floor area of course, now we're expected to use a bit more nouce, but all the same it shouldn't be expected to suffer small overloads of long duration. It's well know that overload protection often doesn't perform well in that situation - hence the warning of regulation 433.1.
