Earthing and protective devices prevent shock and fire.
Currents above ~30 mA through the body can be fatal. Safety measures: insulation, earthing (grounding), RCDs/GFCIs, isolation transformers, lockout-tagout and PPE. Equipotential bonding keeps exposed metal safe. Always isolate before working.
A RCD trips when leakage to earth exceeds 30 mA.
Grounding and protective devices prevent electric shock and fire, which is why they are required by every electrical code.
Earthing and protective devices prevent shock and fire.
Grounding and protective devices prevent electric shock and fire, which is why they are required by every electrical code.
It gives fault current a low-impedance path back to the source, so protective devices operate quickly rather than leaving a metal part live.
A device that compares the current going out and returning, and trips if the difference indicates leakage to earth, such as through a person.
Typical applications include earthing a metal enclosure so that a fault trips a breaker, protecting a person in a bathroom with a residual current device and designing the earth electrode for a building's electrical system.
Study "Lenz's law" first (topic 22 of 106 in Electrical Engineering). It covers the groundwork this topic builds on.
Never rely on a single barrier. Test before touching. Wet conditions raise risk.
A RCD trips when leakage to earth exceeds 30 mA.
The next topic is "Fuses and circuit breakers", which builds directly on this one.
It is classed as Beginner in Electrical Engineering (topic 23 of 106). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.
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