That's a suggestion, not a regulation.
For most residences, the drop from street-line to fusebox is NOT under your control. The power company decides what size wire you get and thus the drop at full current.
The drop on a branch circuit is not a law, just a guide. On a well-pump you are really OK with a larger drop. And this often happens because the well-wire is longer than the house. (Mine is 200 feet.)
And please. NOBODY runs "copper" on the street or to a house/factory, not since the VietNam war. Copper is costly and would get stolen. It's all Aluminum.
ANSI C84.1 not NFPA if I recall correctly. NFPA suggests 3% for the drop to main panel breaker. (NFPA usually adopted as law, virtually never ANSI standards.)
As to stealing copper wire, there have been a few folks injured around here stealing copper wire from what were empty plants. Yes, no workers, but the lines were still hot!
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Voltage dropping ... I was once on a very warm island far away where high voltage poles were installed and electricity was introduced after many years of generator power for the happy few. The connection to the grid and the transformers for commercial use had to be bought by the ones that wanted electricity. For normal citizens a central transformer was installed. The people bought freezers in sizes I had never seen before and of course everyone wanted AC. A lot of AC's, running at 17 degrees setpoint (the "human thermostat" system) in completely unisolated houses...
One evening it was still over 30 degrees at around 22:00. The AC in the house stopped working and even fans were running strange. I measured the mains voltage to be below 190V.
After just wondering and switching off stuff 10 minutes later a loud bang and a blue flash occurred which could be seen from far away. The central transformer of the area had exploded. It was slightly overloaded....
Panic as the fish and meat in the freezers would spoil. The mayor promised the people that the problems would be solved. I asked him how he would do that as the cable gauge was a given and the infrastructure was set for a certain maximum load. He replied that I would not understand... which I found rather unusual to hear 🙂
I returned the next year to see that everything was running perfectly fine. It turned out that the mayor had arranged for 20 kV on the existing 10 kV grid...
Of course ALL transformers had been replaced (often at own expense) but everybody was happy and the mayor was reelected.
One evening it was still over 30 degrees at around 22:00. The AC in the house stopped working and even fans were running strange. I measured the mains voltage to be below 190V.
After just wondering and switching off stuff 10 minutes later a loud bang and a blue flash occurred which could be seen from far away. The central transformer of the area had exploded. It was slightly overloaded....
Panic as the fish and meat in the freezers would spoil. The mayor promised the people that the problems would be solved. I asked him how he would do that as the cable gauge was a given and the infrastructure was set for a certain maximum load. He replied that I would not understand... which I found rather unusual to hear 🙂
I returned the next year to see that everything was running perfectly fine. It turned out that the mayor had arranged for 20 kV on the existing 10 kV grid...
Of course ALL transformers had been replaced (often at own expense) but everybody was happy and the mayor was reelected.
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AC stopped due to built in compressor overload protector.
The 10 kV and 20 kV bit I did not understand.
Here in summer we used to have that problem, everybody went to bed about the same time and started their AC, and some compressors would not start...panic calls to repairmen, and so on.
After some time, as the grid voltages started recovering, all would be well.
Now, the grid is stronger, with more transformers, and inverter AC have reduce starting torque, so less issue now.
The 10 kV and 20 kV bit I did not understand.
Here in summer we used to have that problem, everybody went to bed about the same time and started their AC, and some compressors would not start...panic calls to repairmen, and so on.
After some time, as the grid voltages started recovering, all would be well.
Now, the grid is stronger, with more transformers, and inverter AC have reduce starting torque, so less issue now.
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Instead of the 10 kV as intended they put 20 kV on the main lines/poles. Then one does not need to rewire stuff.
P = U x I 🙂
P = U x I 🙂
I thought you were describing the current situation in Afghanistan until I realized it was in the US .... 😎
Jan
Not really, for 2 reasons:
1) variac does not create energy, to regain 220V from a heavily overloaded line it will pull even MORE current from it, dropping even more voltage ... wich will require an even higher setting because line will now drop to, say, 180V , and so on.
Rinse and repeat.
2) he´s not the only one with that problem, if all or many do the same, whay I describe above will happen all over the island.
3) so rather than variacs , ferroresonant stabilizers, etc. , the REAL solution is to feed more power into the island, no magic involved.
Oh yes you do.
Same copper (upgrading it was out of the question: $$$$$$) means same current, but *probably* wire insulators , which I imagine ceramic standoffs, stands 20kV easily.
Of course, that requires new transformers with 20kV primaries instead of current 10kV ones, secondaries remain the same.
I *suspect* primaries and secondaries are wound separately, side by side, and not one around the other, in that case it´s even easier to modify them.
Apparently the isolators were suitable (was my first thought as well then). I remind the complaining of commercial users that had to buy new transformers. All pole mounted. No one bothers, every year they go down when it storms.
When you pay peanuts you get monkeys.
When you pay peanuts you get monkeys.
You mean the transformer primaries were changed to higher voltage, reducing the current?
Complicated monkey stuff.
The local engineers here have to submit a calculation for the voltage regulation if they change the transformer capacity at the same location, the main 11 kV lines are carrying the load of many transformers, they use only about three conductor sizes for those...This gets a better result, less fluctuation issues.
Complicated monkey stuff.
The local engineers here have to submit a calculation for the voltage regulation if they change the transformer capacity at the same location, the main 11 kV lines are carrying the load of many transformers, they use only about three conductor sizes for those...This gets a better result, less fluctuation issues.
Instead of 1 battery they used 2 in series 😉 On the complete grid that is. They just switched everything off and changed the 10 kV standard (by design) to 20 kV. The power company was not the problem, it was too low calculated branch circuits. Apparently they underestimated that everyone would buy large TVs, computers, AC's, extremely large freezers. The allowable current is the same but the voltage doubled. P = U x I. Example: 10 kV and maximum 100A is 1 MW. Doubling the voltage results in 2 MW. No one in the civilized world would make such a change but they did, forcing many many people to replace the still new self bought transformer.
I bet you can guess how they do internet there 🙂
I bet you can guess how they do internet there 🙂
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Here in Ukraine those wire thiefs are quite smart. They usually do their things right.
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That can be almost ok. A bit illegal of cause but physically the 10 kV rated well-designed isolation will work (some time) with 20 kV applied. Because at 6-10-35 kV lines we have usually quite a large margin in isoltation. At least it is better than totally overloaded transformer.
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Almost unimaginable was one copper thief who survived but was badly injured sued the plant owner for damages and won a jury trial. The owner was a giant corporation and the thief penniless. So out of sympathy the jury accepted the argument the owner should have taken more safeguards to prevent such injuries! Apparently getting past the fence and climbing the towers did not count compared to the self inflicted misery. Not sure what happened on the appeal that would have been determined by only real judges. Most likely a compromise to give the idiot some amount of money less than the cost of the lawyers and other additional legal costs.
A reason the thief was not in prison was practical, he certainly couldn’t do much of anything again and why should the state pay the high costs of his ongoing medical needs.
A reason the thief was not in prison was practical, he certainly couldn’t do much of anything again and why should the state pay the high costs of his ongoing medical needs.
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Not many there cared about what can and can not be done. I have seen many illegal practices there. Nothing regulated. People have AC's and installation is so so with stuff often leaking. They can buy cylinders with refrigerant and fill them every now and then instead of solving the leak. Garbage is either burnt, thrown in the sea or left at the road side. Double glazing was unknown, people used AC with the windows/doors open. Internet was done the quick and easy way with illegal high power stuff at maximum power setting beaming to a relay on top of the mountains and then beaming to the city/village. All wireless of course, no cables were laid even though the ground is not hard or rocky.
Everything I see as "quality" is unknown there. Many things I learned as "caring about the environment" are also not done there. I also learnt that is is not a question of money but of mentality.
Everything I see as "quality" is unknown there. Many things I learned as "caring about the environment" are also not done there. I also learnt that is is not a question of money but of mentality.
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A few years ago there was a power outage here, for about 35 minutes, afterwards we came to know it was because a transformer blew up and they had replaced it! 35 minutes!😱
How is that even possible?!
How is that even possible?!
Sometimes there are reserve (spare) transformers (and breakers) installed by design, with all switchgear needed to just do several operations to turn off the broken one and to turn on that spare unit into work.