Busbar Clearances
Busbar Clearances
(OP)
Does anyone know where to find the miniumum allow outdoor and indoor clearances for 5k to 35kV Bus bar systems in switchgear and vaults? I do not seem to find anything in the NESC.
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RE: Busbar Clearances
If the switchgear or bus section can be taken out of service and grounded as a unit, then the clearance between its individual phases is an engineering decision*. The clearances between the components being worked on and the adjacent equipment, which may still be energized, should be addreesd by the working clearances.
*These clearances are determined by the equipment's BIL, breakdown potentials of air, contaminants, how far a rat can step when standing on one energized bus bar (I've seen this failure mode numerous times), etc.
RE: Busbar Clearances
RE: Busbar Clearances
NEC article 490-24 titled Minimum space separation states, "In field-fabricated installations, the minimum air separation between bare live conductors and between such conductors and adjacent grounded surfaces shall not be less than the values given in Table 490-24. These values shall not apply to interior portions or exterior terminals of equipment designed, manufactured, and tested in accordance with accepted national standards".
Hope this will help.
RE: Busbar Clearances