Hi All
I would appreciate some help with a few questions here regarding cables sizing, I'm using the latest 18th edition, amendment 2.
Q1. p.443, Table 4CQ - derating factors for groups cables - in the table it states "cables touching" but then Note 2 says "horizontal clearances between adjacent cables exceed twice their overall diameter no rating factor need be applied". Which is is?! haha For a cable to be considered as part of a group - does it need to be touching the other cables? Or within 2D of them?
Q2. If we use Reference method D ,which is for cables in the ground, do we also use Cd = 0.9 as it is in the ground? Or do we only use Cd when it's a non-D reference method?
Q3. I'm trying to work out a rating factor for some SWA which is drilled through a wall. A wall which contains insulation. What reference method do we use for some armoured drilled through a wall? Table 4E4A, p.464 only has reference method's C, E, & D. I would imagine passing through a hole in a wall is more like reference method B? As the hole is similar to a piece or conduit? Any thoughts?
I would appreciate some help with a few questions here regarding cables sizing, I'm using the latest 18th edition, amendment 2.
Q1. p.443, Table 4CQ - derating factors for groups cables - in the table it states "cables touching" but then Note 2 says "horizontal clearances between adjacent cables exceed twice their overall diameter no rating factor need be applied". Which is is?! haha For a cable to be considered as part of a group - does it need to be touching the other cables? Or within 2D of them?
Q2. If we use Reference method D ,which is for cables in the ground, do we also use Cd = 0.9 as it is in the ground? Or do we only use Cd when it's a non-D reference method?
Q3. I'm trying to work out a rating factor for some SWA which is drilled through a wall. A wall which contains insulation. What reference method do we use for some armoured drilled through a wall? Table 4E4A, p.464 only has reference method's C, E, & D. I would imagine passing through a hole in a wall is more like reference method B? As the hole is similar to a piece or conduit? Any thoughts?
