My brother in law worked for years on the CN railroad. Then just before he retired he was struck by lightning twice. The second time put him out of commission. He was the best conductor they ever had.
In an installed wiring system, that first fault could be anywhere and sit idle for years. If the transformer fed multiple buildings, it could be in any one of them. Then years later, the 2nd fault happens causing a ground fault, possibly through a person. But it would be near impossible to find both faults so you'd have to tear our the entire wiring installation and start over. By building in the first fault intentionally, the 2nd fault is cleared by the fuse/breaker and that reveals the circuit to inspect. Not to mention, having a grounding rod in the earth, static build up is mitigated, induced currents by nearby lightening [or large inductive loads switching] are mitigated reducing arcing and there is a resistance path that will cap the voltage spikes if the center tap/neutral is lost.
Why doesn't the first ground fault cause an issue? Is it because the impedance of the path back to the source is too great to draw a substantial current to trip an overcurrent protection device? Does the second ground fault (I'm assuming in close proximity to the first) create a low impedance path where a large amount of current can flow and trip the OCPD?
@@kyle6094If you know calculus, you know for instance that the indefinite integral ∫ x dx = 1/2 x² + C, and that if you leave off the +C on an exam, you lose points. Well, voltage is the integral of the electric field, and so it has a + C term. The value of C could be anything, but grounding one side of the transformer secondary sets C to zero. It doesn't cause any current to flow. But it causes the other terminal to have a definite voltage, cycling between +120√2V and -120√2V. Shorting that voltage to ground (the second fault) causes lots of current to flow.
First ground fault has no path to the source. Voltage is always between two points, like from one side of transformer to the other. Grounding one side is like attaching a wire with nothing on the other end. The second ground fault is like connecting the other end of the wire to the other side of the transformer secondary winding.
7200 V line voltage single phase rural and home lines here in C ND. Transformed down to 120/240 volts. I have seen farm homes function with the ground wire torn down and laying on the ground all because there are ground rods on the neutral lines and boxes. Then there is 3 phases for larger applications. ALL on the line and boxes earth grounded neutrals for your protection and for leveling hte ground plane! Then there is the safety ground on our appliances for our protection as well.. Distribution lines to substations are much higher voltage.
Don't know why but a couple years ago I began to wonder if I had ever bonded the ground to Neutral in my 100 amp main panel. So I removed the cover and looked.NO. I had not. For over 20 years I had had no problems what so ever. I bonded it with the supplied screw. I case of an EMP or carrington event you are going to want that bonded to help keep from turning the inside of your walls into a toaster. Sub panels are not bonded but it does not hurt to give each one a grounding rod so you don't have to run another wire [ground] back to the main. In an industrial setting never use large wire nuts on wiring large motors. They burn up and ruin your motor from single phasing. Use the lugs made for big motors. CAREFUL!! one mistake with electricity can cost you a limb or your life!! Been my experience that HVAC people are better electricians than electricians are.
Karma is like electricity… Moral hubris (forgiveness of yourself and others) is the ground wire that shorts out the high static charge of energy you put out (doing crap 💩 in your life) No ground wire can kill you! Everything is built on electrical principles. The Law will CHARGE you with a crime and put you in a CELL (battery) until you are DISCHARGED 😵💫
