I have been asked to explain the difference in coordination study and a selective coordination study. I thought they were the same, but selective was put in front to better explain it. I am being told that they are not the same. Please help.
Charles
Yes they are technically the same, however 'Selective coordination' has come to mean the circuits need to meet the requirements of NEC 700, 701, and 708 for emergency systems.
Selective coordination usually means extremely good coordination in some localities this is down to .01sec (which is often called 100% coordination) while in others .1s is good enough, still other areas, such as the State of Wisconsin, use terms like "as far as practicable.
It is not unusual to have to resort to 'certified' combinations of circuit breakers or fuses to meet 'selective coordination' (all the major vendors have selection aids).
