Published: 14 October 2014
Category: Q&A
Colin asks this question, which concerns cable voltage ratings, specifically 300/500V cabling. It has been answered by the ECA (Cables, Wiring and Wiring Accessories):
This Q & A is one of thousands posted in our Technical Expertise area, and answered on a daily basis by our Voltimum Experts.
Question: I’ve been looking for definitive guidance on whether 300/500V cable is not recommended for 400V circuits (as opposed to not permitted).
Clearly, the system single-phase RMS voltage is less than the cable rated voltage to earth so, on the face of it, a 300/500V cable is permissible.
Any guidance - including custom and practice and experience based guidance – would be most welcome.
Answer: Generally speaking, 300/500V rated cabling can be used for 230V (Uo) / 400V (U) supplies – single- and three-phase.
Note, however, that there is a requirement in Section 704 - construction and demolition site installations - for 450/700V rated cabling to be used for voltages exceeding reduced low voltage.
To see many more Q & A in Voltimum UK's Experts Area, please click on the link. Experts from leading organisations provide online answers to your technical questions on a broad range of subjects. Our searchable database of existing Q & As now contains over 3,500 entries; you can browse through them here.