The circuit breaker at the electrical mains trips at home when there is a thunderstorm outside. Why does this occur?
[Physics] Circuit breaker Trips during thunderstorm
electric-circuitselectricityelectrostaticseveryday-life
Related Solutions
To start with one could have an ac current never grounded anywhere , for a household generator for example. The reason one grounds at the generator is for safety so the ground can pick up any miss chance, as it is a practically infinite sink for electrons. Only one of the two lines can be grounded of course :).
It was found though that due to capacitences the ac neutral even though it starts with zero at the ground ends up in households with some voltage difference dependingon the distances traveled from the last grounding of the supply circuit. I have measured up to 45 volts to the ground difference on the neutral in the 220 we have here.
The household is grounded to some water pipes etc for the same reason it starts grounded, so the outside of appliances is safe for the casual user from small accidents.
However IF at the service panel, the neutral was not connected to earth ground (so the neutral left floating), then we definitely don't have a closed circuit, yet my intuition tells me somehow current would still flow into earth in a short circuit condition.
Sure, due to the infinite sink for electrons of the earth of course the circuit will close to the ground whether the short circuit was from the neutral ( floating) or the live, both would be live in this hypothesis. Grounding at the factory/generator is for safety of use, reduces probabilities of fatal accidents, and in order to assure a stable voltage difference to the user, not floating where then the accidental shorts would be more dangerous. As it arrives floating a bit by the effective circuit the current traverses to the homes, houses have to be grounded again for safety reasons. Having one of the two wires close to ground voltage reduces probabilities of accident by 1/2
Looking up "what happens when lightning strikes a house" on google
(it is a .php file so I had to use printscreen)
See also this youtube video.
So yes, avoid taking a bath during a close by storm.
Have a look at this answer What will happen when lightning strikes on the surface of the deep sea? which has some numbers of the energy in a strike. By the time part of this energy reaches the plumbing it is like any other dangerous short of electricity wiring, and more because of the power behind a strike.
Best Answer
For a given amount of resistance (combined resistance of all the circuits in your computer, or home, or city), the amount of current which flows is proportional to the voltage. (I=V/R)
When lightning strikes a line, it induces a voltage spike. Traditional circuit breakers are current-sensing devices (whether solid state or electromechanical). So, a temporary spike in voltage (V) will, for a fixed resistance (R), create a temporary spike in current (I). If the spike is big enough, it trips the circuit breaker.
In the pre-electronics age, conventional (electromechanical) circuit breakers were good enough, because they could trip fast enough to prevent excessive heating and thus fires.
Unfortunately, modern electronics can be destroyed by a voltage pulse within microseconds, long before an electromagnetic circuit breaker can trip. Thus, the need for solid state (usually MOV-based) surge protectors.
A little history on the MOV, in case you're interested: https://www.youtube.com/watch?v=CiBXN82vzNQ