currenteddy
New User
- Location
- United States
- Occupation
- Electrician
Utility company's 7200 v step down 480 transformer failed. No one was around it was in the middle of the night. Our service panel inside the MCC was roughly 250 ft away from the transformer. There was no load at all on the 1600 amp breaker. The failure of the power company's transformer seemed like a bomb went off burned everything around it to a crisp 30 ft. Now when you look at the underground risers which were 6 coming out of the concrete 4 occupied with parallel 4x 500mcm per phase. It looked like a flame from hell went through all occupied and unoccupied conduits The insulation is crisp as far as I can see. You can also see the two empty conduits had black soot inside. I though a 1000 volts to ground per phase there all showing dead short. Started separating individual wires some were dead short some not still showed below 1 megaohm. Now if you go to the secondary side of the service transformer wires are clean. Could of been a fault in the underground feeders not sure or rapidly violet flame was led by oxygen straight into the concrete encased conduit and made the exit through MCC side.
The owner of the company asked if it could be spliced if we find the wire burned only halfway. I did not recommend splicing a 1600 amp service we are going to need to remove and replace the wire one conduit at a time. hopefully we don't have to make another duct bank. I always like to think safety over money, being the wire itself is going to cost 35,000 dollars I understand the owners concern. Any thoughts on the matter or advice? Ive been working at industrial plants for the last 15 years and Ive never ran into something like this.
The owner of the company asked if it could be spliced if we find the wire burned only halfway. I did not recommend splicing a 1600 amp service we are going to need to remove and replace the wire one conduit at a time. hopefully we don't have to make another duct bank. I always like to think safety over money, being the wire itself is going to cost 35,000 dollars I understand the owners concern. Any thoughts on the matter or advice? Ive been working at industrial plants for the last 15 years and Ive never ran into something like this.