aLWAYS_lEARNING-112532
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I just re-read your comment. If this is life safety as in Article 517, the rules in Article 700 do not apply.Exception:
Selective coordination shall not be required between two overcurrent devices located in series if no loads are connected in parallel with the downstream device.
what about - iF a fault happened at panel ls, if LS main and Feeder LS arent coordinated feeder LS would trip and activate the gen unnecessarily. Should that be a concern?The overlap between Feeder LS and LS main is acceptable. If you have overcurrent devices in series with no other loads in parallel, they do not have to coordinate. An easy way to keep it straight is to look at what would lose power if an overcurrent device were to open. Any other overcurrent devices that result in the same loads losing power are not required to coordinate.
This is a school, but wondering if rules still appliesDoes the exception to 700.32 apply to your installation.
I just re-read your comment. If this is life safety as in Article 517, the rules in Article 700 do not apply.
Out of curiosity, how do you know you have an overlap? The only way to know is to provide the coordination study.Per NEC, do all breakers in this life safety circuit need selectivity, or only need selectivity between the main swgr breaker and all downstream breakers. Right now I have overlap between feeder ls and ls main
View attachment 2579785
No, it will be article 700 and would not be Life Safety.This is a school, but wondering if rules still applies
That is just wrong the Engineer shouldn't confuse by calling it life safety.This is a school, but wondering if rules still applies
Not a concern. It is impossible to coordinate two overcurrent devices that are the same size, which I am assuming these are.what about - iF a fault happened at panel ls, if LS main and Feeder LS arent coordinated feeder LS would trip and activate the gen unnecessarily. Should that be a concern?
No. The generator starting is not part of the coordination criteria.what about - iF a fault happened at panel ls, if LS main and Feeder LS arent coordinated feeder LS would trip and activate the gen unnecessarily. Should that be a concern?
I have them plotted with SKMOut of curiosity, how do you know you have an overlap? The only way to know is to provide the coordination study.
Are the circuits supplied by this system Article 700 or Article 701 circuits? If not, there is no requirement for selective coordination.This is a school, but wondering if rules still applies
Yeah.Are the circuits supplied by this system Article 700 or Article 701 circuits? If not, there is no requirement for selective coordination.
from my limited experience (1 year internship) it has been a common setupPersonally, I would never put a main breaker after an ATS. If it trips, they whole system is out, and the generator isn't going to help.
I see no way that this complies.
Agree, it seems common, but that doesn't make it a good idea.from my limited experience (1 year internship) it has been a common setup