Insights Blog
-- Browse All Articles --
Physics Articles
Physics Tutorials
Physics Guides
Physics FAQ
Math Articles
Math Tutorials
Math Guides
Math FAQ
Education Articles
Education Guides
Bio/Chem Articles
Technology Guides
Computer Science Tutorials
Forums
Trending
Featured Threads
Log in
Register
What's new
Search
Search
Google search
: add "Physics Forums" to query
Search titles only
By:
Latest activity
Register
Menu
Log in
Register
Navigation
More options
Contact us
Close Menu
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Forums
rccb
Recent contents
View information
Top users
Description
A residual-current device (RCD), residual-current circuit breaker (RCCB) or ground fault circuit interrupter (GFCI) is an electrical safety device that interrupts an electrical circuit when the current passing through a conductor is not equal and opposite in both directions, therefore indicating leakage current to ground or current flowing to another powered conductor. The device's purpose is to reduce the severity of injury caused by an electric shock. This type of circuit interrupter cannot protect a person who touches both circuit conductors at the same time, since it then cannot distinguish normal current from that passing through a person.
If the RCD device has additional overcurrent protection integrated in the same device, it is referred to as RCBO. An earth leakage circuit breaker may be an RCD, although an older type of voltage-operated earth leakage circuit breaker (ELCB) also exists.
These devices are designed to quickly interrupt the protected circuit when it detects that the electric current is unbalanced between the supply and return conductors of the circuit. Any difference between the currents in these conductors indicates leakage current, which presents a shock hazard. Alternating 60 Hz current above 20 mA (0.020 amperes) through the human body is potentially sufficient to cause cardiac arrest or serious harm if it persists for more than a small fraction of a second. RCDs are designed to disconnect the conducting wires ("trip") quickly enough to potentially prevent serious injury to humans, and to prevent damage to electrical devices.
RCDs are testable and resettable devices—a test button safely creates a small leakage condition, and another button resets the conductors after a fault condition has been cleared. Some RCDs disconnect both the energized and return conductors upon a fault (double pole), while a single pole RCD only disconnects the energized conductor. If the fault has left the return wire "floating" or not at its expected ground potential for any reason, then a single-pole RCD will leave this conductor still connected to the circuit when it detects the fault.
Ground-Fault Circuit-Interrupter (GFCI)
The GFCI device is listed to UL 943, and has a trip threshold to ensure let-go can occur. The Let-go threshold was established through testing by C. F. Dalziel and published as part of an IEEE Paper titled "Let-Go Currents and Voltage" The GFCI listed device is a requirement in many applications as part of the National Electrical Code (NFPA 70). Section 210.8 of this installation Code is the primary reference for the installation requirements of the GFCI but other requirements can be found in Chapters 5, 6, and 7 of the NEC.
View More On Wikipedia.org
Forums
Back
Top