I was under the impression that in most consumer “surge protectors” the MOVs were connected across hot and neutral.
at any rate, if we’re dealing with a direct or near-direct strike, I wouldn’t really put too much stock into the surge protector. That bolt of lightning just jumped through miles of air, it isn’t going to care about a silly plastic box you have plugged into the wall.
I just popped in to point the interested reader towards the article Why Three Prongs?, which explains a lot of this in an entertaining fashion.
Think of electricity as venom from a snake. If something goes wrong, you want to force the snake to bite the ground, and not you. The electrical ground puts the snake’s face at all times right in front of the f’in floor, not your hand.
To expand on this a bit, this is why the ground prong is always longer than the other two, on a plug. That way, it guarantees that the first thing to make contact will always be the ground, which is safe no matter what.
Also, some folks have mentioned that ground wires are typically color-coded green. While this is one possibility, sometimes ground wires are instead left uninsulated. Since the ground wire should never carry significant current and should never be at a different voltage than anything else uninsulated, this is safe.
How sensitive are circuit breakers? Are residual current devices installed by default? Because I know some appliances that become tingly if not grounded, meaning current is flowing to ground, but nothing trips.
Circuit breakers aren’t that sensitive. A 15 amp breaker will probably not trip at 16 amps. It takes a bit of overcurrent to make them trip. ETA: A regular breaker will not trip due to a ground fault. They only trip on excessive current.
In the U.S. an RCD is generally referred to as a GFI or GFCI (ground fault circuit interrupter). They are required in places like kitchens and bathrooms and a few other places but are not installed on all outlets. They have been required since the mid 1970s or so. There is no requirement to retrofit them into existing homes so houses built prior to that will probably not have them installed. Arc fault circuit interrupters (AFCI) have been required for the last ten years or so in places like bedrooms. These devices protect you from something like a frayed extension cord causing a fire, which a regular breaker and a GFCI will both fail to detect. Again, there is no requirement to retrofit these into older homes.
GFCIs typically trip at somewhere between 5 and 30 mA, so it is possible for it to be a bit tingly to the touch and not quite trigger the GFCI. You’re right on the edge of triggering the GFCI though.
I don’t know what the requirements are in other countries or when they went into effect.
Circuit breakers are sensitive to high current (more than 15 or 20 amperes) flowing thru the hot wire of the circuit. The breaker isn’t sensitive at all to where the current goes for the return path – through the neutral wire, through the ground wire, through a metal part on the appliance then through a human to a plumbing pipe – it’s all the same to the circuit breaker.
So circuit breakers care nothing about that. All they deal with are direct shorts or excessive loads, which will cause an overload of the wires, leading to overheating and the risk of a fire. That’s when they will break the circuit.
in the USA GFI/RCD can be found in the device (convenience receptacle or in an appliance cord/plug) or in a GFI breaker that is installed in the breaker box.
locations currently required to have convenience receptacles protected by them are places where a person could be easily a path to ground (kitchens, bathrooms, basements, garages, outdoors).