GFCI / GFI : A circuit breaker that quickly shuts off the flow of electricity (via relay) at a speed between 25–40 milliseconds, when it detects a difference (as small as 4 milliamps) between the electric current exiting the system compared to the current entering.
These are common terms referring to the same thing, categorized as RCD‘s (Residual Current Devices) —
RCBO = Can detect current imbalance (GFCI) in addition, detects overcurrent, trips circuit when higher than expected current enters the system.
GFI vs GFCI: What’s the difference?
There is a big debate around GFI vs GFCI on electrical discussion forums. It seems that even the professionals aren’t too sure if there’s difference between Ground Fault Interrupters (GFI) and Ground Fault Circuit Interrupters (GFCI). This article is going to settle the issue. We’ll be answering all your questions around electrical safety and GFCI/GFI protection.
I was surprised to see the uncertainty, even among electricians, as to the difference between GFI and GFCI. Most say it’s the same thing. Then why are there two terms? Let’s end the confusion with the definition and description of Ground Fault and Ground Fault Circuit Interrupters (GFI/GFCI).
While both GFI and GFCI refer to basically the same thing, a device that breaks the current when ground interference is detected, there is a slight difference. The word Circuit being the crucial thing here.
Technically, GFCI refers to a breaker that protects an entire circuit. This would be a GFCI breaker on your electric distribution panel and will protect multiple outlets. A GFI is a local Ground Fault Interrupter, it is at the outlet and not on the panel. So the slight difference here is whether you have protection over several outlets, that you reset at your panel, or single protection that you reset at the outlet. Inline GFI protectors can be used for extension cords and individual appliances. These plug into the outlet, or extension cord, and offer local protection at the point of use. In the end, they all do the same thing and these terms are used interchangeably.
What is GFCI and How does it Work?
The primary purpose of a Ground Fault Circuit Interrupter (GFCI) is to prevent electrocution when we make contact with an electric current. GFI is just a localized version of the same thing. Regulations governing the installation of GFCI or GFI protection differs form one local authority to the next. Generally, GFCI is mandatory whenever there’s a risk of moisture causing accidental electrical contact. This would be outdoor electrical installations, garages, and electrical outlets close to plumbing outlets, like bathrooms and kitchens. Many countries require full panel GFCI protection for all electric sockets. Full panel protection is preferable as electrocution does not only result through contact with moisture. Broken insulation on an electric cord can also cause electrocution. This can happen anywhere, at any time.
VIDEO | GFCI — A Visual Demonstration
If there is a difference between the hot current flowing into a circuit and that flowing out of the neutral, it means current is being lost through a leakage. This usually means current is flowing directly to the ground. If we make contact with an electric current, it will flow through our body to the ground. This means that an unrestricted amount of electricity will move through our bodies, until that circuit is broken, or interrupted. The result, electrocution which can be deadly. Hence the need for protection against electrocution in any situation where a person may make contact with an electric current.
A GFCI beaker is designed to detect any loss of current between the hot and neutral wires. They are incredibly sensitive, detecting around 4 -- 5 milliamps electric loss. A coil around the hot supply measures the electric field around the wire. The neutral return has a similar coil. These measure the current flowing through both conductors. The moment a difference is detected between the two electric fields, the GFCI switch will trip. This happens almost instantly (± 20 – 30 milliseconds).
GFCI breakers will have a test function that causes a deliberate ground leakage. The user is protected by an insulted test button. When the test button is pressed, the GFCI breaker should open immediately. In other words, the GFCI will trip. Testing should be conducted regularly and the GFI outlet or GFCI breaker should be replaced if it is not functioning correctly.
GFCI Questions & Answers
There are many common questions surrounding the use of GFCI and GFI. Here is where you’ll find the answers.
Q: What is ground fault?
A: Ground fault is a term used to describe an electric current that is short circuited directly to the ground. This means that the electric current is not directed back to the source via a neutral wire, which is the normal path for electricity. Instead, an external conductor (like water) or damaged insulation causes the current to flow directly to the ground.
Q: When do I need GFCI?
A: Ideally, every electric outlet should have GFCI or GFI protection. It is of particular importance where an external factor, like moisture, can cause an unseen ground fault.
Q: Why does my GFCI keep tripping?
A: A GFCI circuit breaker is designed to protect the user from electrocution if a ground fault is detected. If the GFCI trips, it usually means a ground fault is caused by water, a faulty appliance, or broken insulation on the electrical wiring. However, any GFCI protector has a limited lifespan. Generally, these devices should last 10 – 20 years but they can fail in as little as 5 years. It is important to determine whether the CFCI device is tripping because of a ground fault, or a malfunctioning GFCI.
VIDEO | GFCI Keeps Tripping — WHY?
Q: How to rectify a GFCI trip?
A: First we need to identify what is causing the GFCI to trip. Unplug all appliances connected to the GFCI outlet. This could be several outlets on the same circuit. In other words, you want no load on the circuit that is tripping. With no load on the circuit, reset the GFCI breaker. You can test the circuit by plugging a light into the outlet. If the light works and the circuit does not trip, you know that the GFCI and internal wiring is fine. This means that there is problem with one of the appliances plugged into that circuit.
You will need to test all appliances one by one. Start by plugging each appliance into the outlet individually. You’ll identify the faulty appliance when the GFCI breaker trips. Check this appliance for moisture or damaged insulation on the wires. You can also use a multimeter to test for continuity between the hot wire and the body of the appliance. Then do the same test between neutral and the body of the appliance. If you cannot identify the cause, or are unable to repair it, have a qualified technician inspect and repair that appliance. Refrigerators and washing machines are common causes for a GFCI trip because of the moisture that collects in these appliances. Sometimes, you may simply need to leave them disconnected for a while to allow the moisture to evaporate and then reconnect them.
If the GFCI trips with no load, or a load that you know to be safe, then the problem lies either with the GFCI breaker or the wiring supplying the outlet. You can do a visual inspection of the outlet, looking for possible moisture contact or damage – like a cracked or burnt outlet. Blow hard into the outlet to dislodge any moisture or conductive material that may be inside the outlet. If there is no visible external damage, you’ll need to check the wiring that supplies the outlet. Check for burnt, cracked, or damaged insulation on the wiring. If the outlet has a ground wire, you can use a multimeter to check for continuity between the ground wire and both the hot and neutral wires.
Any electric circuit that shows continuity will be indicated by a beeping sound when the multi-meter dial is turned to the continuity setting. Continuity between either hot or neutral wires and a conductor connected to ground is a clear indication of a ground fault.
If none of the above tests reveal positive results, you can assume that the GFCI is faulty and needs to be replaced.
Q: Can I install a GFCI myself?
A: If you’re asking this question, then the answer is no. It is not too complicated to install or replace a GFCI outlet or panel breaker. However, if you have no experience doing this, it’s best to use a qualified electrician. Inline GFCI protectors, plug directly into an outlet or extension cord and these are easy for anyone to install.
Q: How to test a GFCI outlet?
A: Testing a GFCI outlet is easy and should be done regularly. Start by plugging a light into the outlet and switch it on. Press the “TEST” button on the outlet (or distribution panel). You should see the reset button move to the outer position and the light will go out. This means the GFCI is working properly and you’ll need to press the reset button to restore power. If the light remains on, the GFCI protector needs to be replaced.
Additional Resource on GFCI Standards and Information
NOTE : The Next edition for NEC (National Electrical Code) standards is set to be released in 2022. NEC standards are created by NFPA (National Fire Protection Association), which is a non-profit organization founded in 1896 with the goal of eliminating deaths and injuries, in addition to property and economic loss related to issues associated with electrical hazards.
The NFBA proactively work to make all of our lives safer by creating standards for optimal safety with how electrical systems are built. In our fast moving world, rooted in the use of energy, they are an organization essential for creating and maintaining a safer world in how energy is incorporated into our lives.
They consult with active professionals to ensure their data and standards are leading edge, accurate and foremost, pro-active in its approach to safety. Our world is constantly changing and they continue to change and update accordingly.