This is a true story.
I was fresh out of college with a shiny new Bachelor's degree in electrical engineering - a B.S.E.E. I had studied electronics since I was 9. At that age, my father gave me a copy of the American Radio Relay League's (A.R.R.L.) handbook. It was loaded with esoterica involving resistors, capacitors, inductors, triodes, tetrodes, pentodes, and mysterious concepts like resonance, reactance, and impedance. I was hooked and started reading and learning, and began taking radios apart, fixing radios, fixing TVs, and building circuits on a foot-square project board (literally a board, it was made of wood with standoffs for tubes and component connections). I went to night school at age 13 to study radio repair. I was too young to enroll but I audited the class. I got good grades, too. By age 14 I was operating my own ham radio station. How could I not end up being an electrical engineer?
I had struggled to pay for college. Now I was a new graduate but I had no money. I had a job as a missile guidance system design engineer, but no actual money. Nada. I borrowed $200 from my mother to put down a deposit on a tiny one-room trailer. And I use the word "trailer" intentionally; it was more trailer than mobile home. But it was affordable, so I moved in. Shortly after I moved in, the electrical power started flickering off and on. Before going to work one morning, I called the landlord about it. He said he would send over an electrician to fix it. I came home from work that day and arrived mere minutes after the "electrician".
At this point I should explain something about my trailer's electrical power. In the small plot of land that passed for a backyard there was an electric utility pole. On the pole was mounted a fuse box. Inside the fuse box was a single 30 amp fuse and a disconnect switch. An electrical cord terminated with a standard 3 prong plug ran from the fuse box to my trailer. On the bottom of the trailer (so it was out of the elements), mounted close to the side of the trailer, was a standard receptacle - like the one you plug your toaster into. The electric cord from the fuse box simply plugged into my trailer like your toaster plugs into the wall outlet.
So, as I came around the corner of the trailer, what I saw was a guy sitting on the ground taking this plug off the end of the fuse box wire.
"Found the problem?" I inquired.
"Yeah. Bad plug."
I watched him take it off, and I watched him put the new plug on the wire. I observed that he crossed the hot and neutral wires from the way they were connected on the old plug.
"You've got the wires connected backward," I said.
"It don't matter," he replied.
"Sure it does."
"No it don't."
"Of course it matters whether you've got ..."
He shot me a stern look and said, "Look! I've been doing this for twenty years and I'm telling you it don't matter!"
Even though I was an electrical engineer by training and had worked in and around electronics for over 12 years, I decided not to argue with him. From his point of view I was a kid. What could I know? Hell, maybe he knew something I didn't know. Maybe he was right and it really didn't matter. But from my point of view, he was about to do something very dangerous.
A number of homes in the mobile home park were all powered by a large transformer. This transformer could pump out hundreds of amps all day long, day after day, without being overloaded or getting hot. Under a severe overload it could supply thousands of amps. The neutral wire out of the transformer was grounded at the transformer. The neutral wire in my trailer was grounded at the trailer. By crossing the wires at the plug, this electrician was going to apply a direct short circuit to this large power transformer. A direct short circuit limited only by the slight resistance of 12 gauge copper conductors. This looked bad. Very bad. Those thousands of amperes would flow through my fuse box. And, for a few milliseconds, through that 30 amp fuse.
The electrician plugged the fuse box cable into my trailer and walked over to the fuse box. I slowly backed up, putting about 10 feet between me and the fuse box. He threw the switch that connected the transformer to my trailer.
The fuse box exploded. A tongue of flame at least six feet long shot out of the fuse box, roaring past the electrician's head like a monster blowtorch from hell. The sight was so incredible it was burned into my visual memory. It was unbelievable. It was the mother of all short circuits. If this electrician's head had been directly in front of the fuse box when he threw the switch, he would probably be dead now. Or, seriously burned and blinded at the very least. I was impressed.
The electrical blowtorch died after a few seconds. The electrician was stunned. I mean stunned!
"What happened?" he asked me. "What happened? Why did it do that?"
"I told you, you crossed the wires to the plug."
"It shouldn't have mattered," he said, but with far less certainty now than before. He sat down in the grass and took the plug off and put it back on ... with the wires uncrossed this time. The fuse box had a hole where the fuse had been, so the electrician wired across it. He wired across the burned disconnect switch as well. Now, the only disconnect was at the trailer. Where the power cable from the fuse box was plugged into the trailer - that was now the disconnect.
The electrician refused to plug the power cable into the trailer. He wouldn't do it, because that meant connecting the monster killer transformer - the Forbidden Planet Krell power unit - to the thing (my trailer) that was obviously possessed by an electrical demon. So I walked over to it, picked up the plug, and plugged the cable into the trailer. Naturally, nothing happened - nothing, that is, except I had power to my trailer once again.
Now the electrician was impressed. He shook his head. "How did you know that? You must fix radios or somethin' for a living."
"Yeah," I replied. "Something like that." And that was the end of that. Except for one thing.
I mentioned the fuse box panel had a hole where the fuse had been. I knew the fuse had come out of that box like a bullet. I looked for it, and I found it. It had flown about 30 feet. It was an ordinary household fuse with an Edison screw-type base. When I found it, the fuse was still screwed into its socket that had been mounted inside the fuse box. The fuse and socket had been ejected together like a bullet. I took the burned fuse/socket object to work and placed it on a shelf above my desk where I would see it every day. It seemed there was a valuable lesson there and I wanted to remember it.
I was fresh out of college with a shiny new Bachelor's degree in electrical engineering - a B.S.E.E. I had studied electronics since I was 9. At that age, my father gave me a copy of the American Radio Relay League's (A.R.R.L.) handbook. It was loaded with esoterica involving resistors, capacitors, inductors, triodes, tetrodes, pentodes, and mysterious concepts like resonance, reactance, and impedance. I was hooked and started reading and learning, and began taking radios apart, fixing radios, fixing TVs, and building circuits on a foot-square project board (literally a board, it was made of wood with standoffs for tubes and component connections). I went to night school at age 13 to study radio repair. I was too young to enroll but I audited the class. I got good grades, too. By age 14 I was operating my own ham radio station. How could I not end up being an electrical engineer?
I had struggled to pay for college. Now I was a new graduate but I had no money. I had a job as a missile guidance system design engineer, but no actual money. Nada. I borrowed $200 from my mother to put down a deposit on a tiny one-room trailer. And I use the word "trailer" intentionally; it was more trailer than mobile home. But it was affordable, so I moved in. Shortly after I moved in, the electrical power started flickering off and on. Before going to work one morning, I called the landlord about it. He said he would send over an electrician to fix it. I came home from work that day and arrived mere minutes after the "electrician".
At this point I should explain something about my trailer's electrical power. In the small plot of land that passed for a backyard there was an electric utility pole. On the pole was mounted a fuse box. Inside the fuse box was a single 30 amp fuse and a disconnect switch. An electrical cord terminated with a standard 3 prong plug ran from the fuse box to my trailer. On the bottom of the trailer (so it was out of the elements), mounted close to the side of the trailer, was a standard receptacle - like the one you plug your toaster into. The electric cord from the fuse box simply plugged into my trailer like your toaster plugs into the wall outlet.
So, as I came around the corner of the trailer, what I saw was a guy sitting on the ground taking this plug off the end of the fuse box wire.
"Found the problem?" I inquired.
"Yeah. Bad plug."
I watched him take it off, and I watched him put the new plug on the wire. I observed that he crossed the hot and neutral wires from the way they were connected on the old plug.
"You've got the wires connected backward," I said.
"It don't matter," he replied.
"Sure it does."
"No it don't."
"Of course it matters whether you've got ..."
He shot me a stern look and said, "Look! I've been doing this for twenty years and I'm telling you it don't matter!"
Even though I was an electrical engineer by training and had worked in and around electronics for over 12 years, I decided not to argue with him. From his point of view I was a kid. What could I know? Hell, maybe he knew something I didn't know. Maybe he was right and it really didn't matter. But from my point of view, he was about to do something very dangerous.
A number of homes in the mobile home park were all powered by a large transformer. This transformer could pump out hundreds of amps all day long, day after day, without being overloaded or getting hot. Under a severe overload it could supply thousands of amps. The neutral wire out of the transformer was grounded at the transformer. The neutral wire in my trailer was grounded at the trailer. By crossing the wires at the plug, this electrician was going to apply a direct short circuit to this large power transformer. A direct short circuit limited only by the slight resistance of 12 gauge copper conductors. This looked bad. Very bad. Those thousands of amperes would flow through my fuse box. And, for a few milliseconds, through that 30 amp fuse.
The electrician plugged the fuse box cable into my trailer and walked over to the fuse box. I slowly backed up, putting about 10 feet between me and the fuse box. He threw the switch that connected the transformer to my trailer.
The fuse box exploded. A tongue of flame at least six feet long shot out of the fuse box, roaring past the electrician's head like a monster blowtorch from hell. The sight was so incredible it was burned into my visual memory. It was unbelievable. It was the mother of all short circuits. If this electrician's head had been directly in front of the fuse box when he threw the switch, he would probably be dead now. Or, seriously burned and blinded at the very least. I was impressed.
The electrical blowtorch died after a few seconds. The electrician was stunned. I mean stunned!
"What happened?" he asked me. "What happened? Why did it do that?"
"I told you, you crossed the wires to the plug."
"It shouldn't have mattered," he said, but with far less certainty now than before. He sat down in the grass and took the plug off and put it back on ... with the wires uncrossed this time. The fuse box had a hole where the fuse had been, so the electrician wired across it. He wired across the burned disconnect switch as well. Now, the only disconnect was at the trailer. Where the power cable from the fuse box was plugged into the trailer - that was now the disconnect.
The electrician refused to plug the power cable into the trailer. He wouldn't do it, because that meant connecting the monster killer transformer - the Forbidden Planet Krell power unit - to the thing (my trailer) that was obviously possessed by an electrical demon. So I walked over to it, picked up the plug, and plugged the cable into the trailer. Naturally, nothing happened - nothing, that is, except I had power to my trailer once again.
Now the electrician was impressed. He shook his head. "How did you know that? You must fix radios or somethin' for a living."
"Yeah," I replied. "Something like that." And that was the end of that. Except for one thing.
I mentioned the fuse box panel had a hole where the fuse had been. I knew the fuse had come out of that box like a bullet. I looked for it, and I found it. It had flown about 30 feet. It was an ordinary household fuse with an Edison screw-type base. When I found it, the fuse was still screwed into its socket that had been mounted inside the fuse box. The fuse and socket had been ejected together like a bullet. I took the burned fuse/socket object to work and placed it on a shelf above my desk where I would see it every day. It seemed there was a valuable lesson there and I wanted to remember it.
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