Document: NRC Regulatory Guide
Document ID: 8e45dce1-e1e7-4415-b1dd-7e2a610e545b
Document Type: regulatory_guide
Title: Fire Protection for Nuclear Power Plants (Rev. 4)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2023/ML20231A835.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.189
CFR Part: 
CFR Title: 

Content:
1E electrical cables should meet the separation guidelines of RG 1.75. When the electrical cabling is covered by separation criteria required for both post-fire safe shutdown and accident mitigation, the more stringent criteria of Regulatory Position 5.3.1.1 apply. (Compliance with post-fire safe-shutdown requirements may be achieved without separation of redundant Class 1E cabling by providing alternative or dedicated shutdown capability (see Regulatory Position 5.4); however, this does not preclude the separation criteria of RG 1.75 for redundant Class 1E cables used in accident mitigation.) For plants with a construction permit issued before July 1, 1976, where cables important to safety do not satisfy the provisions of RG 1.75, all exposed cables should be covered with an approved fire-retardant coating or a fixed automatic water fire suppression system. DG-1359, Page 63 4.1.3.5 Transformers Transformers that present a fire hazard to equipment important to safety should be protected as described in Regulatory Position 7.3 of this guide. 4.1.3.6 Electrical Cabinets Electrical cabinets present an ignition source for fires and a potential for explosive electrical faults that can damage not only the cabinet of origin, but also equipment, cables, and other electrical cabinets in the vicinity of the cabinet of origin. Fire protection systems and features provided for the general area containing the cabinet may not be adequate to prevent damage to adjacent equipment, cables, and cabinets following an energetic electrical fault. Energetic electrical faults are more of a concern with high-voltage electrical cabinets (i.e., 480 volts (V) and above). High-voltage cabinets should be provided with adequate spatial separation or substantial physical barriers to minimize the potential for an energetic electrical fault to damage adjacent equipment, cables, or cabinets important to safety. Rooms containing electrical cabinets important to safety should be provided with areawide