IEEE 1268:2016 pdf free download – IEEE Guide for Safety in the Installation of Mobile Substation Equipment
4.Electrical clearances
Guarding and clearances to energized parts are given in Rule 124 of the 2002 (National ElectricalSafety Code (NESC)[B1])2 for U.S.utilities. Users of this guide in other jurisdictions should reviewapplicable local codes. Clearances to energized parts for safety of personnel are given in Table 124-1,“Clearances from Live Parts”of the 2002 2012 NESC unless adequate insulation or suitable barriersare provided. Rule 124A.3 of the 2002 2012 NESC states a minimum vertical clearance of 2.6m(8ft 6in) between any ungrounded part or parts of indeterminate potential and any permanentsupporting surface where workers might stand. Temporary structures might be required to maintainproper clearances The user should review and refer to the applicable local codes and standardsapplicable to their installation.
The following 4.2 Phase-to-ground and 4.3 refer phase-to the-phase clearances for those temporaryconnections required to install the mobile. These clearances will not be tested and therefore need toshould follow the requirements of the NEC，ANSI C37.32-2002, ete-IEEE Std 1427TM6 or any otherjurisdictional codes.Tested devices such as the mobile substation (if tested) with its permanentlyinstalled equipment may have clearances that are less than those of the temporary connectionsrequired to place the mobile in service.
Mobile substations or transformer trailers might be installed in many locations. The trailers might beinstalled on utility property or non-utility property.On utility property, the mobile substation mightbe installed inside or outside the permanent substation fence. The mobile substation located outsidethe
permanent substation fence might be located next to the substation, a distance away from thesubstation,on the transmission line right-of-way, or on non-utility property. When the mobilesubstation is located outside the substation fence or on non-utility property, special attention needsto be given to the touch and step voltages at the mobile substation fence because it is the most likelypoint of contact by non-utility personnel. Transferred potential rise between the mobile (and itsfencing, if applicable) and the substation needs to be managed,
lf the mobile substation must be energized before the fence and gate grounding and any necessarystation counterpoise and high-resistivity ground cover described in this Guide are completed. it isadvisable to create a nonconductive (e.g. with the brightly colored marker tape usually installedabove underground cables)visual barrier on nonconductive supports well outside of any temporary.fencing. In such cases, it may also be advisable to station temporary security personnel at the site toprevent public access and warn utility personnel of the fence hazard. In all such events, the mobilesubstation equipment and trailer(s) shall be properly grounded before energizing as describedherein, and every effort shall be made to finish the fence grounding, etc. before the end of the nextday.Personnel touching or going inside the temporary fence and gate(s) and/or installing suchgrounding shall utilize personal protective equipment so as to guard themselves from hazardous.touch potentials, and shall be properly trained as to the unusual hazards involved.