IEEE Std 628-2020 pdf free download

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.
B.1 Raceway systems
Aluminum can react with certain chemical sprays used in some containment structures and release hydrogen. which may accumulate in explosive conccntrations. The amount of aluminum raccways inside thcsc containment structures is considered an inventoried item for review. Galvanized raccways are recommended inside containment structures: however, the amount of zinc used inside the containment structure is also considered an inventoried item for review (see Regulatory Guide 1.7 lBS 1).
B.1.1 Conduit and underground duct systems
B. 1.1.1 Conduit application recommendations
The following recommendations should be considered for conduit applications:
a) Zinc-coated RMU and IMC may be exposed in wet and dry locations, embedded in noncinder concrete at least 5 cm (2 in) thick, and directly buried in soil. When used in cinder fills, it should be protected by noncinder concrete at least 5 cm thick. Where alkaline conditions exist, consideration should be given to a protective coating. Copper-silicon alloy, brass, or plastic plugs should be used to plug spare conduits in wet locations.
b) Aluminum RMC may be exposed in wet and dry locations. Because aluminum conduit may corrode in concrete, it should not be used without an external protective coating. It should not be installed in soil.
C) The top of duct banks should be located below the frost line. Duet banks should run as straight as possible with manholes and handholes used to reduce the number of bends. Bends should have the largest radius possible consistent with the duct configuration and material. Offsets in duct runs should be avoided. Manholes and handholcs should have a sump to facilitate the use ofa pump when required. Duct joints should be staggered both horizontally and vertically.
d) Hot-dip galvanized RMC should be used for installing low-level signal cables in the isolated cases where a concrete-encased duct bank contains conduits for power and low-level signal cables and additional electromagnetic shielding is required.
c) Exposed nonmetallic and protective coatings on metallic raceways require additional design considerations. Because PVC produces chlorine gas and is not self-extinguishing in a fire, reducing its exposure to free air should be considered.IEEE Std 628-2020 pdf free download.