Figure 9-9.—Underground service to building.transformer to the junction box and to theservice equipment.Service EntranceThe starting point for interior wiring is theSERVICE ENTRANCE, which brings powerfrom the service conductors to the service equip-ment. Refer again to figure 9-8. As shown in thisfigure, the service entrance conductors areconnected to the service drop at a point justoutside the building. These conductors maybe approved single conductors run througha protective raceway, such as rigid metallicor nonmetallic conduit. The service entranceconductor may also be an approved type ofservice entrance cable that does not need racewayprotection unless it is likely to be damaged byabrasions or from being struck by passing equip-ment. Where single conductors are used, theymust be insulated as require by the NEC®. TheNEC® also specifies the size wire that may be usedas service entrance cable.Also shown in figure 9-8 is a SERVICEHEAD. A service head, frequently called aWEATHERHEAD, is used with a raceway toprovide an entrance for the conductors into thebuilding. The weatherhead is designed to preventthe entrance of rain into the raceway. It is alsodesigned to reduce abrasion to the insulation.A SERVICE ENTRANCE SWITCH (left-hand side of fig. 9-10) provides a means ofbrings the power to the building, are called theservice lateral. Sometimes these conductors aretied to an overhead distribution system, and theyrun down the pole into the ground before theyare run to the building. In other cases, the entiredistribution system, except for the transformers,is underground. The service lateral may beconnected to a secondary main, or, if the buildingis served by separate transformers, it is connectedto the transformers.The service lateral may be installed in rigidconduit, either metallic or nonmetallic, or it canbe installed with underground service entrance(USE) cable. The figure shows the layout of anunderground service lateral run from theFigure 9-10.—Typical layout for entrance switch, lighting panel, and power panel.9-7
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business
