moosewl
Electrical
- May 12, 2008
- 14
I have 208/120V panel fed from a delta / wye transformer. Upstream of the transformer is a 480V switchgear with electronic trip breaker. The GF on this breaker is a residual sensor and is set at 140A. The transformer is about 150' from the switchgear, and the panel is 20' from the transformer. Last night an eltcrican was installing a new breaker in the panel and unfortunately he neglected to install the terminal shield. The dead-front cover contacted one of the terminals, and the result was that the terminal grounded itself and blew the metal away on the dead-front. The GF in the upstream breaker did not trip.
Did the breaker not trip becasue:
1) The residual current was too small due to it being on the primary of transformer?
2) The fault blew away the panel cover and cleared itself before the breaker tripped?
3) Other reson?
Did the breaker not trip becasue:
1) The residual current was too small due to it being on the primary of transformer?
2) The fault blew away the panel cover and cleared itself before the breaker tripped?
3) Other reson?