IEEE Std 628-2020 pdf free download – IEEE Standard Criteria for the Design, Installation, and Qualification of Raceway Systems for Class 1E Circuits for Nuclear Power Generating Stations.
4. Design
4.1 General
4.1.1 Material selection In the design and intallation of raceway systems, considention shall be given to the relative structural integrity of aluminum versus steel when subjected to heat from postulated fires.
NOTE- Flexible conduit my not accommodue reative diplacement in all inalltins For ditional guidelies pertaining to raceway systems, se Annex B.”
4.1.2 Structural integrity Raceway systems for Class 1E circuits are not Class IE per IEEE Sid 308TM; however, they shalll be designed to seismie Ctegory 1 requirements to prevent filure during a seismie event. Documentation requirements for the raceway system shall be in accordance with Clause 7 of this standard. Individual components (conduit, tny, et.) within the maceway system are a subset of, and distinguished from, the maceway system. Those individual conmponents shall meet the industry standard requirements (i.e, Certificate of Conformance to ANSIC80.1 and UL6, sce 47)ncssary to spport the srucual and scismie alculatins Standard industry pactice has alowed difent requirements for conduit as to cable tray.
AIl materials shall be manufactured to requirements that support the 10 CFR 50 Appendix B calculations, which show the stnuctural integrity of the scismic raceway system for Class IE circuits. As a minimum, the design shall sdhere to the basic requirements of this standard and of IEEE Sud 3847M. This will help ensures that the raceway system is designed to perfom its functions, and not degrade the safety fiunctions of adjacent safety-related systems during and after experiencing all conditions postulated to occur in is environment. Cleanances with respect to other systems shall be established and provided to help ensure that movement due to loads and load combinations (see 4.10.1) will not afet the integrity of the rceway system. Relative displacement of the nceway system to other systems, equipment, or structures shall be considered in the design ofraceway systems.
The rceway supprts sallbe designed to acommodatec ifrential sttlement and deflections between structures.
4.1.3 Layout Raceways shall not be located close to heat sourcs unless cables are sleted or derated for the bighest expected ambient temperature. Longitudinal expansion of rceways shall be considered in areas with varying temperatures. The design of raceways shall accommodate the intallation of qualified fire stops where nceways penetrate a fire barrier. For adioall fire considerntions, see IEEE Sud 690m.
4.2 Separation criteria
4.2.1 Design requirements The design requirements for plhysical independence and separaion of noceways containing Class IE circuits are contained in IEEE Std 384.
4.2.2 Raceways
Raceways shall be separated according to the voltage lasifcation of the cables contained within them (sce IEEE Std 690).
4.3 Grounding
Metallic raceways shall be electrically continuous and electrically connected to the station ground grid in accordance with IEEE Std 665TM.
4.4 Raceway identification
Raceways shall be marked in accordance with the requirements of IEEE Std 384; embedded conduit shall be marked at all access points.
4.5 Raceway system protection
Raceway systems in hazardous areas shall be designed in accordance with IEEE Std 384.
4.6 Environmental considerations
The selection of materials used for raceway systems and the finishes required shall be based on the environmental conditions expected where the raceway systems are installed. To meet the requirements for combustible gas control, materials for raceway systems to be installed in containment shall be selected with due consideration to minimizing the generation of hydrogen gas following a design basis event (Regulatory Guide 1.7 [B5]).”7 For additional guidelines pertaining to environmental considerations for raceway systems,see Annex B.IEEE Std 628 pdf download.