Selective Coordination for Legally Required Standby systems - interpretation

Status
Not open for further replies.

donw

Senior Member
Location
Arizona
The code says "Legally required standby systems overcurrent devices shall be selectively coordinated with all supply side overcurrent protective devices." My question is regarding other overcurrent devices, not in the standby path, but may affect the standby supply. For example, suppose you have a main breaker that feeds everything. Are you required to coordinate all breakers in the system - or just the ones in the standby path, up to the main breaker?
 
In Wisconsin, we are required to coordinate everything below the transfer switch with the 'first' device on the normal source side and all devices on the emergency side.
 
Good reference.

A similar thread just about a week or two ago came to the opposite conclusion, and convinced me that coordination of the normal supply breakers were required.

Now I back to thinking this is only required for the generator sides and load sides of the ATS.
But don't forget that the load side devices must be coordinated based on the normal source fault current, as that is what is available until the ATS operates.
 
Status
Not open for further replies.
Top