ABSTRACT
This discussion provides an overview of the reasons and methods for reducing sheath losses in large cables. While calculations are shown, all of the details are not covered as completely as in the Institute of Electrical and Electronics Engineers (IEEE) Guide 575 [1]. A complete set of references is included in that standard. The reader is urged to obtain a copy of the latest revision of that document before
16.1 Introduction .................................................................................................. 313 16.2 Cable Is a Transformer.................................................................................. 314 16.3 Ampacity ...................................................................................................... 315
16.3.1 Shield Losses .................................................................................... 316 16.3.2 Shield Conductivity .......................................................................... 316 16.3.3 Bonding Jumper Capability .............................................................. 318
16.4 Multiple-Point Grounding ............................................................................ 318 16.4.1 Advantages ........................................................................................ 318 16.4.2 Disadvantages ................................................................................... 318 16.4.3 Discussion ......................................................................................... 318
16.5 Single-Point and Cross-Bonding .................................................................. 319 16.5.1 Advantages ........................................................................................ 319 16.5.2 Disadvantages ................................................................................... 319 16.5.3 Background ....................................................................................... 319 16.5.4 Single-Point Bonding Methods ......................................................... 319 16.5.5 Induced Sheath Voltage Levels ......................................................... 320 16.5.6 Depiction of Bonding Methods......................................................... 323
16.5.6.1 Multigrounded Cable Run-Two or More Grounds. Solid, Multigrounded Circuits ........................................... 323
16.5.6.2 Cross-bonded Circuits ........................................................ 324 16.5.6.3 Continuous Cross-Bonding ................................................ 324 16.5.6.4 Auxiliary Cable Bonding ................................................... 325 16.5.6.5 Continuous Cross-Bonding, Star Ground .......................... 326
References .............................................................................................................. 326
designing a “single-point” grounding scheme. Another excellent reference is the 1957 Underground Systems Reference Book [2].
