Bonding

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electric1

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Per a recent inspection we have been requested to install a ground (I think he means bond)to a battery rack (steel frame). The rack contains (2) batteries (24VDC) supplying DC power to a newly installed SCADA panel. We cannot find a reference in the NEC for this requirement. Inspections has not to date provided reference to a code article either. Any ideas where or if this requirement exists in the NEC?
 
Re: Bonding

Electric1. do not have a code book in front of me, but i think it is 250.4 or 6. The reason is, it is likely to become energised. The size of the bonding jumper will depend on if you have the batteries fused or not, and if one of the polarities is grounded or not. General rule of thumb is a 6 AWG conductor.

I install hundreds of 48 VDC battery @ 2000AH strings in my buisness, a 6 AWG is always used, and we never install battery fuses. The 6 AWG acts as an fusible link. If the ungrounded battery terminal were to become shorted to the battery rack, the 6 AWG would burn into and tell local operations the battery rack is energized with 48 VDC.

The other method is to use a non-conductive and non-corrosive battery rack like fiberglass.

[ June 10, 2004, 01:54 PM: Message edited by: dereckbc ]
 
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