A
AReynolds
I am trying to select a suitable conductor size from Fig 4D1A of the BS 7671 Book, and am encountering a problem because the circuit does not conform to one Reference Method. The circuit conductors leave the distribution board in wall mounted steel trunking, then run through some steel conduit that passes through about 20cm of concrete wall, then finally through some PVC wall mounted trunking and two more 20cm concrete walls.
Technically, the points at which the cable pass through the three walls are Reference Method A, while the rest of the circuit would be considered Reference Method B. Given that the tabulated current using Reference Method A will be more stringent, do I have to consider the entire circuit as being Reference Method A for the purpose of determining the tabulated current, or can I consider it as being Reference Method B, given that 60cm of the 20m cable run are Reference Method A, with the remaining 18.2m being Reference Method B?
Technically, the points at which the cable pass through the three walls are Reference Method A, while the rest of the circuit would be considered Reference Method B. Given that the tabulated current using Reference Method A will be more stringent, do I have to consider the entire circuit as being Reference Method A for the purpose of determining the tabulated current, or can I consider it as being Reference Method B, given that 60cm of the 20m cable run are Reference Method A, with the remaining 18.2m being Reference Method B?