Tinned Strander Copper Ground Conductor

[living2learn]

I am doing a raised floor installation and the drawing calls out for a 2/0 tinned stranded copper ground conductor. My question lies in the chapter 9 table 8 of the NEC which has the dc resistance of the conductor with .096 ohms/kft and .3 ohms/kft. My understanding is the coated column refers to tinned conductors which protect from corrosion I assume but the resistance is just so much higher. For a solidly grounded system especially with sensitive electronics wouldn't you want the lowest resistance to ground? Is there something/advantage I am missing with the tinned ground conductor.

 

[rcw retired EE]

The grounding impedance is what matters, not the resistance. The difference in resistance is inconsequential when you look at the resistance of the connections and the impedance of the overall system. A flat bar has better high frequency characterisitcs than a #2/0 awg wire.

 

[cuky2000]

Hi kellyshort,

Recheck again. I believe the 0.03 refer to Ohm/km

The correct value should be the next column, 0.101 ohm/kft.

The resistance difference should be less than 5%.