Title: Reading Assignment
Course: WGF 107 DEVELOPMENT > Section: Content

Title | Reading Assignment
Image |

Sub-Title | Fool-proofing Those Devices: Testing RCDs/GFIs/GFCIs
Content
Testing[edit]

RCDs can be tested with built-in test button to confirm functionality on a regular basis. RCDs if wired improperly may not operate correctly and are generally tested by the installer to verify correct operation. Use of a solenoid voltmeter from live to earth provides an external path and can test the wiring to the RCD. Such a test may be performed on installation of the device and at any "downstream" outlet.

In North America, RCD (“GFCI”) receptacles invariably have rectangular faces and accept so-called decorator face plates. GFCI outlets can be mixed with regular outlets or with switches in a multigang box with a standard cover plate. Arc Fault Circuit Interrupters (AFCI) are required by current NEC code in locations such as sleeping rooms and incorporate GF protection. As a result, the slightly more expensive GFCI circuit breakers for load centers are less commonly used in residential applications.

In Canada and the United States, two-wire (ungrounded) (NEMA-1) outlets may be replaced with GFCIs to protect against electrocution, and a grounding wire does not need to be supplied to that GFCI. The outlet must be labeled as such. The GFCI manufacturers provide tags for the appropriate installation description. GFCI receptacles can be connected to also protect all the downstream receptacles on that circuit.

GFCI devices approved for protection against electric shock trip at 5 mA within 25 ms. A GFCI device which protects equipment (not people) is allowed to trip as high as 30 mA of current; this is known as an Equipment Protective Device (EPD). "RCDs" with trip currents as high as 500 mA are sometimes deployed in environments (such as computing centers) where a lower threshold would carry an unacceptable risk of accidental trips. These high-current RCDs serve for equipment and fire protection instead of protection against the risks of electrical shocks.

GFCI outlets are required by code in most places where an easy path to ground exists, such as wet areas, rooms with uncovered concrete floors and outdoor areas. In the U.S., successive editions of the National Electrical Code required GFCIs for additional areas: underwater swimming pool lights (1968); construction sites (1974); bathrooms and outdoor areas (1975); garages (1978); near hot tubs or spas (1981); hotel bathrooms (1984); kitchen counter receptacles (1987); crawl spaces and unfinished basements (1990); wet bar sinks (1993); and laundry sinks (2005).^[8]
Image | Internal mechanism of RCD (residual current device/GFI/GFCI)
Content | The GFCI is rated to trip quickly enough to prevent an electrical incident. If it is properly installed and maintained, this will happen as soon as the faulty tool is plugged in. If the grounding conductor is not intact or of low-impedance, the GFCI may not trip until a person provides a path. In this case, the person will receive a shock, but the GFCI should trip so quickly that the shock will not be harmful. The GFCI will not protect you from line contact hazards (i.e. a person holding two "hot" wires, a hot and a neutral wire in each hand, or contacting an overhead power line). However, it protects against the most common form of electrical shock hazard, the ground-fault. It also protects against fires, overheating, and destruction of wire insulation. Because GFCIs are so complex, they require testing on a regular basis. Test permanently wired devices monthly, and portable-type GFCIs before each use. All GFCIs have a built-in test circuit, with test and reset buttons, that triggers an artificial ground-fault to verify protection. Ground-fault protection, such as GFCIs provide, is required by OSHA in addition to (not as a substitute for) general grounding requirements.
Links/Uploads
Residual Current Devices – Wikipedia http://en.wikipedia.org/wiki/Ground_Fault_Interruptor

See also[edit]

 | Energy portal

- Arc-fault circuit interrupter (AFCI)
- Earth leakage circuit breaker
- Insulation monitoring device
- Domestic AC power plugs and sockets

Electrical Student Training Manual (92-pg.) – OSHA http://www.cdc.gov/niosh/docs/2009-113/pdfs/2009-113.pdf

GFCI – OSHA https://www.osha.gov/SLTC/etools/construction/electrical_incidents/gfci.html
Attributions
Image courtesy of OSHA – U.S. Department of Labor, and

Additional Image courtesy of WIKIPEDIA – The Free Internet Encyclopedia

Content courtesy of Wikipedia – The Free Internet Encyclopedia

Content courtesy of OSHA – U.S. Department of Labor