nvpowerdoc
Member
- Location
- Las Vegas, NV
I'm looking for an "Industry Feel" where AHJs / Inspectors are headed when enforcing the portion of the "Selective Coordination" definition that states, "...
for the full range of available overcurrents, from over-load to the maximum available fault current, and for the full range of overcurrent protective device opening times associated with those overcurrents", with respect to 2020 NEC 701.32, 702.32, 708.54, 620.62, and 695.3(C)(3) [and earlier versions].
This language appeared as early as 2014 NEC, but very few "Coordinating Engineers" / Vendors seem to adopt or utilize breakers (particularly Molded Case Circuit Breakers) that coordinated below 100mS (though that was/is the intent of the Code). With the recent (Aug 2021) CA OSHPD PIN indicating they will no longer accept breakers (OCPDs) that do not "selectively coordinate" only to 100mS (an exception in the CEC). I believe the exception many have used over the past six years will soon be going by the way-side, especially in CA.
I realize each manufacturer (ABB/GE, Eaton, SqD/Schneider, Siemens, etc.) has their own "Selective Coordination" Publications that provide information on breaker pairings and the level of fault current to which these pairings do coordinate, but all those except ABB/GE are highly limited to very small fault current magnitudes (typically far less than 10kA) in the Instantaneous region. We are beginning to find in certain Jurisdictions across the US (as Eaton is telling us) that we basically have to use the Eaton (Cooper/Bussman) Fused Panelboards, or we have to use very expensive UL1066 LVPCBs, along with ZSI and limited Single Line topologies to achieve such selective coordination goals using breakers only.
I realize Cooper/Bussman has been pushing "Fused Panel Boards", or the idea of "Fusing Pairs" to achieve real selective coordination where required in the Code for the past 15-20years. Perhaps Eaton has figured out where the Code is going and that is why they bought-out the C-B product line.
So as a Coordinating Engineer with over 20yrs experience doing Short Circuit, Coordination, and Arc Flash Studies, I wonder where the industry is really headed on this matter as only Eaton and Mersen currently have Fused Panel Board Solutions.
for the full range of available overcurrents, from over-load to the maximum available fault current, and for the full range of overcurrent protective device opening times associated with those overcurrents", with respect to 2020 NEC 701.32, 702.32, 708.54, 620.62, and 695.3(C)(3) [and earlier versions].
This language appeared as early as 2014 NEC, but very few "Coordinating Engineers" / Vendors seem to adopt or utilize breakers (particularly Molded Case Circuit Breakers) that coordinated below 100mS (though that was/is the intent of the Code). With the recent (Aug 2021) CA OSHPD PIN indicating they will no longer accept breakers (OCPDs) that do not "selectively coordinate" only to 100mS (an exception in the CEC). I believe the exception many have used over the past six years will soon be going by the way-side, especially in CA.
I realize each manufacturer (ABB/GE, Eaton, SqD/Schneider, Siemens, etc.) has their own "Selective Coordination" Publications that provide information on breaker pairings and the level of fault current to which these pairings do coordinate, but all those except ABB/GE are highly limited to very small fault current magnitudes (typically far less than 10kA) in the Instantaneous region. We are beginning to find in certain Jurisdictions across the US (as Eaton is telling us) that we basically have to use the Eaton (Cooper/Bussman) Fused Panelboards, or we have to use very expensive UL1066 LVPCBs, along with ZSI and limited Single Line topologies to achieve such selective coordination goals using breakers only.
I realize Cooper/Bussman has been pushing "Fused Panel Boards", or the idea of "Fusing Pairs" to achieve real selective coordination where required in the Code for the past 15-20years. Perhaps Eaton has figured out where the Code is going and that is why they bought-out the C-B product line.
So as a Coordinating Engineer with over 20yrs experience doing Short Circuit, Coordination, and Arc Flash Studies, I wonder where the industry is really headed on this matter as only Eaton and Mersen currently have Fused Panel Board Solutions.
