Can anyone suggest possibilities of why we are reading 120vAC across CB A2-3 TIE on the attached one-line diagram? All breakers are closed unless indicated w/ "open". Readings were taken at VM1 and VM2 as shown on one-line. VM1 readings were 120vAC across the line side and load side of CB A2-3...
We have two 1600A adjacent feeder circuit breakers(CBA3 and CBA4)on a rooftop substation. Both CBA3 and CBA4 feed busducts BD3 and BD4 respectively. Last night CBA4 opened on an Instantaneous fault of 7kA. All loads off of CBA4 were de-energized as expected. However, we also found that a machine...
When can an Arc Flash propogate from the feeder bus of a panel to the line side of the Main? What constitutes a barrier between the Main section and a feeder section of a distribution panel? I'm curious how other firms deal with these questions. It's real easy for the Arc Flash firm to just...
Given:
In an existing installation, a standalone panel has an SCCR label that reads 5kA symmetrical rms. A current limiting fuse mounted outside of this panel and on the line side of this panel has an instantaneous peak let through current of 10kA and an rms symmetrical let through current of...
