Underground feeders

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Location
Denver
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Contractor
The situation:
Existing 200 A, MLO, 3PH, 120/208 panel fed from underground PVC.
When originally installed in '81 the ground conductor was not installed with the current carrying conductors but instead was installed in a separate conduit. The ground conductor is bonded at the panel and at the ground bus in the MDP.
Owner is wanting to have an arc flash analysis done so my question is this; would having the ground conductor installed as noted have any adverse effect on the AFA or does the GC need to be installed in the same conduit as the current carrying conductors?
 
There is a provision/exception to not running all the phases/grounded/grounding conductor in the same PVC/non metal raceway.

During a fault condition the proximity/distance of the equipment grounding conductor from the ungrounded conductors may affect the calculation and/or clearing time. I’m curious to how much it would be affected being in PVC conduit and how far away the two conduits are. Hopefully others will chime in.
 
Last edited:
The situation:
Existing 200 A, MLO, 3PH, 120/208 panel fed from underground PVC.
When originally installed in '81 the ground conductor was not installed with the current carrying conductors but instead was installed in a separate conduit. The ground conductor is bonded at the panel and at the ground bus in the MDP.
Owner is wanting to have an arc flash analysis done so my question is this; would having the ground conductor installed as noted have any adverse effect on the AFA or does the GC need to be installed in the same conduit as the current carrying conductors?
Imo I would not think that the Equipment grounding conductor is going to effect the available fault current. It is going to effect if a fault is going to clear the overcurrent device. I might be wrong….we will see what others have to say.
 
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