Coordination Study - 517

[anbm]

517.17(C) only requires to have ground-fault protection fully coordination on normal power....

And 700.27 requires to have fully coordination on emergency side.

Does this mean 517.17(C) allows not to coordinate on other features for circuit breakers (Long, Short time delay, pick-up) if we have to?

 

[richxtlc]

Ground fault protection minimizes damages caused by ground faults not phase-to-phase faults and prevent tripping of the service when the ground fault is on the feeder. The coordination still has to exist for phase-to-phase faults so as to minimize the outage to the system that is at fault. This is especially critical in health care facilities or where emergency systems are required.

 

[steve66]

700.27 requires coordination for the emergency system.

Are you are asking if the normal feed to an emergency system needs to be coordinated (i.e. - the utility power feed to a transfer switch)? I don't think the code is real clear on this issue. But I think most people include the utility feed to a transfer switch as part of the emergency system.

Or are you asking about strictly normal power? I.e. the white receptacles? I don't think there is any requirement for coordination on these systems in a hospital.

Steve

 

[anbm]

I am asking about normal power main gear and distibution feeders, it can be upstream or downstream of ATS or do not feed ATS, strictly on normal side not on emergency side. Thanks!

 

[VUGear]

Most everybody I know that does selective coordination does it for both the normal and emergency sides.