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What is a GFCI or RCD receptacle?

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Answered 2011-01-29 06:43:14

A GFCI (Ground Fault Circuit Interruptor) or an RCD (Residual Current Device)

receptacle is designed to help prevent electrical shock to users of appliances plugged into them. The device constantly monitors the currents flowing in the hot and neutral conductors.

The currents flowing in the hot and neutral conductors should match almost exactly, to within a few milliamps. If the current flows do not match, the device disconnects itself within a few milliseconds, to stop the supply of electrical power to any receptacles it protects.

Because the device does not actually need to check for any ground current, it can be installed without a ground wire. (Unlike the earlier type of GFCI device, which only checked for the presence of some fault current flowing to ground and so needed to be connected to a properly installed ground wire.)

If there is no grounded conductor installed, a GFCI wired in this manner, and any receptacles protected by it, are each required to be clearly marked with a label saying:


This method of changing two-wire ungrounded receptacles to three-wire grounding receptacles is allowed - even though they are not physically tied to the ground - only in a circuit which is protected by a correctly installed GFCI or RCD.

For more information about MCBs and related topics such as ELCBs, GFCIs and RCDs, see the answers to the Related Questions and the Related Link shown below this answer.


As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.

Before you do any work yourself,

on electrical circuits, equipment or appliances,

always use a test meter to ensure the circuit is, in fact, de-energized.




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Related Questions

Can I install a GFCI receptacle from an existing receptacle in the basement?

Yes, there is no reason why this can not be done. In fact a benefit of this is that every receptacle downstream from this new receptacle will also be protected by the GFCI receptacle.

What might happen if the line and load connetions of a feedthrough gfci receptacle were reversed?

Most probably the receptacles downstream from the GFCI would not be protected by the GFCI receptacle.

Do you need a gfci outlet if you have a gfci breaker?

Not if the GFCI breaker is supplying the circuit you are wanting to put the GFCI receptacle into.

What is a GFCI receptacle?

A GFCI receptacle is a ground fault circuit interruptor.For more information see the answer to the Related Question shown below.

If your wall receptacle has tripped but not at the circuit breaker how can this problem be repaired?

If it's a GFCI receptacle and the button is not resetting then change the GFCI outlet.

How do you install multiple GFCI receptacles?

A GFCI receptacle can extend its protection to regular receptacles connected to the output side of the GFCI. Each actual GFCI receptacle should be directly connected to a breaker in electric panel.

What is the weight of a GFCI receptacle?

8 ozs. and will vary by mfr. for an in-wall receptacle.

Can a gfci breaker be used with a gfci outlet?

Yes but it's redundant and may cause unnecessary "tripping" of the circuit. The GFCI circuit breaker is intended to protect an entire receptacle circuit whereas a GFCI receptacle is designed to protect only that receptacle and any which are provided power from its load side. (downstream)

If I have 20 amp GFCI receptacle and would like to add another receptacle to the GFCI Does the new plug also need to be 20 amps?


How many miliamps to trip out a GFCI?

GFCI receptacle are designed to trip on 5 milliamps.

How far do you put a GFCI from water?

How far do u put a GFCI receptacle from water

Will another electrical outlet that is in line with a GFCI outlet cause it to kick off?

A down stream receptacle that is connected to the upstream GFCI will be protected. If the downstream receptacle senses a fault the upstream GFCI will trip.

What does the term GFCI receptacle stands for?

The term GFCI stands for Ground Fault Circuit Interrupter.

How do you reset a GFCI outlet?

Push the reset button in the center of the receptacle. When you first power up a GFCI receptacle is will automatically trip, just reset and you will be good to go.

What is difference between RCCB and RCD?

RCD is a general term for Residual Current Device, which then can be devided by many types like RCCB, RCBO, GFCI ets

What is the function of ground fault circuit interupter?

The function of a GFCI is any fault to ground will automatically trip the circuit. For example, if a hairdryer is plugged into a GFCI receptacle and it is dropped into a sink of water, the GFCI will shut down power to the receptacle.

Can you install an electrical switch before a gfci?

Yes! you can install an switch a head of a GFCI receptacle. This installation is common in some applications to turn on an outside receptacle to control Christmas lights.

Why did the Gfci reset but still no power to outlet?

When power is first applied to a GFCI receptical they will trip the reset. This has to be reset to power the receptacle. If it was wired wrong then the breaker feeding the receptacle may have tripped. Check the source for the receptacle at the electrical panel to see if the breaker tripped the circuit.

How do you check a ground fault interrupter?

Both GFCI breakers and receptacles have a button you can push to test it. You can also get receptacle testers with a GFCI tester on them.

Do you need a gfi plug for a spa if it is being plugged into a gfi circuit?

If your spa is connected with a GFCI circuit breaker you will not need the GFCI receptacle.

May a GFCI receptacle be installed as a receptacle in an old installation where the 2-wire circuit has no equipment grounding conductor?

Actually, yes. The GFCI does not need any ground; it measures "leakage", i.e., an imbalance, regardless of whether there is "ground". The National Electrical Code permits installing a GFCI to replace a completely ungrounded receptacle. Others have said: No. The GFCI is designed to measure an unintended path to ground. Without a good ground reference this is not possible.

What is the electrical symbol for a GFCI receptacle?

== == == == It's a receptacle symbol, usually with "GFCI", "G", or "GFI" written under it. To find out exactly which symbol is used on your prints, look at the electrical legend, which is normally page E-1, E-001, etc.

If a 20 amp receptacle mounted outside must be?

If a 20 amp receptacle is to mounted outside it must be enclosed in a waterproof box and cover and be of the GFCI type.

How do you wire a GFCI or an RCD receptacle?

A GFCI has two sides: LINE and LOAD. The LINE side is where your incoming power to the receptacle is connected. This provides power to the receptacle, and allows the receptacle to disconnect power to itself if a ground fault occurs on something plugged into it. If you have more receptacles 'downstream' that need GFCI protection, you may power them from the LOAD side of the GFCI. This puts all devices wired to the LOAD side under the protection of the GFCI, as if they were plugged into the front of it with a cord and plug. When a ground fault occurs on a downstream receptacle, it will trigger the GFCI, which will disconnect power to all downstream receptacles as well as the devices actually plugged into the GFCI face. To make things easy on yourself, my professional opinion is to never wire anything to the LOAD side of a GFCI. That way when a ground fault trips the device, you don't have to hunt around to find out which GFCI is tripped (there may even be some you don't know about). We build commercial buildings and our crew policy is never to LOAD side anything. If the box has a set of wires coming in and going out to the next receptacle, just connect both sets to the LINE side. ----If you do not understand the work well enough to accomplish it yourself properly and safely, don't try it. Consult a professional electrician, as they are proficient enough to do it properly and safely. When working on electrical circuits and equipment, make sure to de-energize the circuit you will be working on. Then test the circuit with a definitive means to make sure it is off (multimeter with metal tipped leads, voltage tester with metal tipped leads, etc., not a non-contact tester, which is non-definitive.)

How do you wire dual switch-plug gfci which has extra wires?

there should be 5 wires, hot and switched hot for the switch and hot, neutral and ground for the gfci receptacle.

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