For those that don’t know I am an Electrician on the reservation in GA. So we buy 4160V from the power company and use it and transform it to 480V and @120V. Some of the slot machine motors are 300 - 500 Hp. Those giant motors are run on 4160V. That is a dangerous and voltage to work with. Back in the day when the casino was built it didn’t make any since to run those big motors on 480V, the technology wasn’t there. So our primary voltage of 4160 is what we take into our Electrical rooms and use it and transform it as we need it. The accident that occurred Thursday happened when the operators in the control room went to start a 4160V motor for a system fan that cooled our video poker machines. The motor tripped the motor starter overload when they tried to start it, so they went down to the started and reset it. (Standard procedure before they call an Electrician). When they got back in the control room they attempted to start the fan again and the fuse in the Motor Starter Bucket exploded. That shouldn’t happen.
Fuses have a sand like material in them, it sand blasted the cabinet behind the fuse. Notice everything behind the fuse is scoured clean and everything else is covered in soot.
The cabinet door in front of the fuse became molten metal but stayed together.
It then sent an arc of electricity through the top of the bucket blowing a hole into the compartment with the main bus bars.
The arc flash traveled along the bus bars till they came to the end.
Upon reaching the end the power had to go somewhere so it jumped to the edge of the cabinet. It takes alot of energy for electricity to jump open air. Once the arc reached the edge of the cabinet a secondary explosion occurred that vaporized the metal of the cabinet and some of the bus bar.
We still don’t know what exactly caused all this but with this amount of damage we can conclude that our safeties failed to work. The power company mains down the road were tripped. Our breakers failed to stop the inrush current. They power company also sustained damage to some of their equipment as well.
ELECTRICITY IS DANGEROUS LET THE PERFESSIONALS HANDLE IT. The electrical department has been submitting for capital budget to replace this equipment for over ten years. We never thought it was going to fail catastrophically, we just thought one day it won’t work and we won’t be able to fix it. We are professionals and we got caught outside the TeePee with ours tomahawks hanging out, so don’t mess with electricity if you don’t know what you are doing. This incident could have killed someone. I was working in that room the day before this happened. Arc flash temperatures can reach 35,000 degrees Fahrenheit. It only lasted about a half second but this exit sign melted in that half second
Thank the Lord and praise His Holy name no one was hurt. Be safe out there y’all. ****o