Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This Question of the Day concerns domestic electrical installations and running cable in trunking. It is answered by SELECT:

When running twin & earth cables to switch drops and socket outlets in insulated walls, would running them in a yt4 PVC trunking help with the current carrying capacities, or is that unnecessarily expensive?
Answer: You should use table 4D5 from BS7671: 2008 (the 17th Edition) to determine the current carrying capacity of the cable within a wall containing insulation.
If you enclosed the cable in conduit, you should use Table 4D2A.
This should help determine whether any conduit/trunking used would be 'unnecessarily expensive' or not.
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