Re: C1 D1 WW Wet Well
Tom,
Not quite, and without graphics its difficult to explain why. I'll try though.
I?m going to edit out some extraneous content in the first sentence of 501.16(A) and emphasize part of the second.
?bonding jumpers with proper fittings or other approved means of bonding shall be used. Such means of bonding shall apply to all intervening raceways, fittings, boxes, enclosures, and so forth between Class I locations and the point of grounding for service equipment or point of grounding of a separately derived system.
This applies to ??to all intervening raceways, fittings, boxes, enclosures, and so forth?? that are not themselves considered suitable to be EGCs, such as PVC.
As I believe you have described it, the EGC is not considered an adequate ?bond? for the PVC. Why? A ground-fault that may develop between energized conductors and the RMC is ?forced? to return to the source through the RMC/EGC bond in the Classified location. The ground-fault must then traverse all intervening, possibly ?loose,? joints in the RMC and each creates a potential ignition source in the Classified area. Now, depending on where the ground-fault occurs this may happen anyway of course, but a ?hard? bond across the PVC is considered necessary to minimize the probability.
Note: Read carefully, the exception actually emphasizes that the CMP wants the
physically as well as electrically shortest possible ground-fault path.
I should clarify this is not necessarily my personal opinion of minimum ?good practice? but it seems to be the consensus of the Panel. This requirement is routinely overlooked with underground runs of PVC and there is no historical evidence of problems.
My personal concern would be the proper placement of the seals relative to the equipment and boundaries.
Edit: Corrected typo of 501.16(A) reference
[ April 15, 2005, 11:59 AM: Message edited by: rbalex ]