I agree with the fact there is no requirement in the NEC or the NESC of bonding the Manhole Cover. On the DOE project I am on the DOE does not come up with Code arguments but come up with incidents where because the action was not taken an incident happened. Our solution to this was to bond the ring of the manhole itself thus providing a bond between the ring and the cover caused by the weight of the cover. BTW there is no requirement either in the code requiring the bonding of Vault or Substation doors.
