Conductor cross- sectional area | Reference Method 4 (enclosed in conduit in thermally insulating wall etc) | Reference Method 3 (enclosed in conduit on a wall or in trunking etc) | Reference Method 1 (clipped direct) | Reference Method 11 (on a perforated cable tray, horizontal or vertical) | Reference Method 12 (free air) |
| 2 cables, single- phase a.c. or d.c. | 3 or 4 cables, 3-phase a.c. | 2 cables, single- phase a.c. or d.c | 3 or 4 cables, 3-phase a.c. | 2 cables, single- phase a.c. or d.c. flat and touching | 3 or 4 cables, 3-phase a.c. flat and touching or trefoil | 2 cables, single- phase a.c. or d.c. or flat and touching | 3 or 4 cables, 3-phase a.c. flat and touching or trefoil | 2 cables, single- phase a.c. or d.c. or 3 c ables three phase | 2 cables, single- phase a.c. or d.c. or 3 cables three phase | 3 cables, trefoil 3-phase a.c. |