Category Cables; Planning for Power Delivery

The utilisation of category cables for power delivery has been getting ample attention lately – especially given the amendment in NEC (2017), NFPA 70 (2017) and potentially CEC C22.1 (2017 proposed revisions). This attention is related to potential safety issues that may emerge when high power, high temperature and high cabling density are present.

The National Fire Protection Association (NFPA), Chapter 3, Table 725.144, “Transmission of Power and Data,” contains information about the ampacity rating of conductors at various temperature ratings based on gauge and bundle size. UL has created LP certifications (optional – not required by code) to identify cables that are designed and tested to carry the marked current under reasonable worst-case installation scenarios without exceeding the cable’s temperature rating.

This arose through an allowance in the older version of NEC, which allowed electricians to substitute Class 2 and Class 3 data cables (category cables) for 18 AWG wire in certain instances.

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