[ELI5] What does it mean to be “grounded” against electricity, and why does it keep you safe?
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Basically, electricity is lazy. It will follow the easiest route (that is, the route with the least resistance). Grounding gives it a nice easy route somewhere safe where it can dissipate and be no harm to you.
Whenever you have two things with different electric charges, electricity will flow between them. This flow is what makes electricity dangerous, and is governed by two things:
1. How large is the difference between the two charges? (Voltage)
2. How easy is it for the electricity to flow? (Resistance)
If the charge is the _same_ between two things, then no electricity will flow. If it’s too difficult for the electricity to flow quickly, then even if there is a large difference, it won’t flow very fast.
“Ground” typically refers to the thing in any particular electrical system that has the least amount of charge, but it is entirely arbitrary. For a thing to be “grounded” simply means that it is connected to the thing that is “ground” such that both things always have the same charge.
In a home electrical system, the “ground” thing is _literally the ground/earth_. This means that as long as you have the same charge as the earth/house, nothing grounded to the house will ever shock you. Appliances with a grounded plug use the ground connector to connect their outer shells to the home’s ground, which prevents you from being shocked by the outer shell of the appliance.
Ground connectors are also important because when there _is_ a difference in electrical charge between two things, they provide an easy path for the charge to equalize that isn’t you. Humans have a very high resistance, so electricity will flow through other things like a ground connector if it is available instead of you.
Rubber gloves and other insulating protective wear helps when you come in contact with a non-grounded thing by greatly increasing the resistance, thus slowing down the electricity enough that it won’t harm you.
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