Why have Electrical Grounding? What is a Ground Wire?

1) What is Electrical Grounding?

Electrical Grounding is a vital part of any electrical system but many of us will not understand what grounding is, how it works or why its important to the electrical system and to our well-being in our homes. 

Electrical grounding is a process whereby the electrician decides which parts of the building need to be connected to the earthing system. In the UK it is known as Equipotential Bonding and Earthing. 

Certain parts of a building can become a danger when there is an electrical fault such as metal pipework or structural steel. The reason for this is that these metal parts often go into the ground themselves and can provide a reasonable ground or earth path for electrical current. 

The electrician carries out some testing to determine which parts of the building must be earthed and which parts should not be. Grounding is an important process because, if not done correctly, there can be electric shock and possibly fire hazards present during certain times of the operation of the electrical system and under electrical fault conditions.

2) What is the purpose of the Ground Wire?

WHAT ARE GROUND WIRES USED FOR?  Well…. Ground Wires are thick copper wires that are used to connect metal work to a grounding block and then to the Main Earthing Cable for the electrical installation. This can be seen in the picture above. 

There is normally a label or warning regarding these wires as shown. 

3) What is a Ground Rod?

A ground rod is a metal rod, normally coated in copper, that is inserted into the ground to attempt to provide a good earth path for an electrical system. It is not always the preferred method of grounding or earthing for an electrical system as achieving a suitably low resistance reading is very difficult and can often require the use of several ground rods. 

The electrician will carry out some tests to determine the best and safest location to install an earth rod which must be away from other earthing points of other electrical systems. 

This method of earthing an electrical system is often only used in rural areas where there is no earth supplied by the electricity distributor AND there is sufficient land to allow one or more rods to be installed providing a low enough reading for earthing safely. 

4) What happens if there is no grounding to pipes?

If there are metal pipes, structural steel or other conductive parts that are not part of the electrical system present in a building then these could introduce a difference in voltage resulting in electric shock. 

Let us say that an electric kettle goes faulty and the case of the kettle becomes live. You have your hand on the kitchen tap AND touch the kettle at the same time but the tap and pipework are not grounded (connected to the electrical system earthing). 
Because the case of the kettle and the tap have different resistances to earth, a potential difference (or voltage) can appear between the faulty kettle case and the tap.

If the taps were ALSO CONNECTED to the earthing of the electrical system, then when the kettle case became live, the tap would ALSO BECOME LIVE at the same voltage. This would mean there is NO DIFFERENCE in voltage between the two and it would be more difficult to receive an electrical shock. 

It is typically the incoming cold-water pipe that is grounded along with the gas pipe but your electrician may decide that it is necessary to ‘cross bond’ pipework at the boiler for instance by linking all pipework together. This is another purpose of a ground wire. 

5) Is anything else Grounded?

Still unsure about WHAT ARE GROUND WIRES USED FOR? Nearly every metal part of an electrical installation will be or should be grounded. If you have metal switch faceplates or socket outlets in your property then these should be grounded to prevent electric shock risk. Many electrical appliances will also require grounding dependent upon what the manufacturer of the appliance specifies. 

Some metal case appliances may NOT require grounding if the manufacturer has determined that there is no way for the case to ever become live under electrical fault conditions. 

6) How dangerous are Electric Shocks?

Electric shocks can be very serious to our health and if sufficiently large for a long enough duration can result in electrocution. The use of GFCI (Ground Fault Circuit Interrupters) or RCD (Residual Current Devices) is now mandatory in many electrical situations. 

These devices monitor the electrical circuits in your property and check for any missing electrical current that is leaking away from the system. 

The assumption is, if any electrical current is missing from an electrical circuit, then it MUST be leaking through someone delivering an electric shock to them. These devices detect these issues and disconnect the affected group of electrical circuits, single circuit, plug socket or appliance and remove the danger. 

Electrical shocks can cause serious harm or electrocution when they reach levels of around 30mA or above (milli amps or thousands of an amp) which is a tiny amount of electrical current. 

7) Are Ungrounded Outlets Safe?

Ungrounded outlets are not safe. Every electrical outlet or plug socket should be grounded to ensure that any appliances that are used have a safe and low resistance path to earth should an electrical fault occur. 

8) Ground Bar inside a Consumer unit or Electrical Panel

The electrical ground wire needs to be terminated into something and inside the electrical panel there is a grounding bar which all the ground wires can connect to. This grounding bar receives the grounding wires from all the electrical circuits that are used in the property. 

By connecting all the grounding wires together, we are ensuring that there are no dangerous voltages present when an electrical fault occurs and that there is sufficient fault current to turn off a circuit breaker. 

There are many different parts to an electrical panel that perform different functions and the grounding or earthing bar is just one of them. 

9) What about Lightning Protection?

When lightning strikes there can be a massively high voltage that is generated, this can cause serious damage to some buildings. To combat this, any buildings that are likely to be affected by lightning strikes often have a lightning protection system installed. 

A lightning protection system involves running a thick metal strip to the point most likely to be struck by lightning. This is similar to a grounding rod and provides a low-resistance path to earth for any lightning strike and protects the rest of the building from any lightning strikes. 

Lightning will choose the path of least resistance to follow and this important safety feature can protect many historic buildings from damage from direct strikes and from electrical fires. 

10) What are Ground Faults?

There are different types of ground faults in a grounding system. There can be:

• Lack of Proper Grounding
• Broken Grounding Wires
• Fault from Line to Ground
• Fault from Neutral to Ground

A lack of proper grounding is where there are loose connections, high resistances, undersized grounding wires or damaged bare copper wire that is at risk of becoming broken. Where there is a lack of proper grounding, there can be excess electricity that has nowhere safe to flow under electrical fault conditions and as such, electric shock risk can be present. 

Broken Grounding Wires are a common situation that can occur when DIY electrical installation is carried out. Many people that attempt their own electrical installations do not have the knowledge of electrical installation or wiring regulations to carry out work safely and can forget to connect, deliberately leave out or damage the grounding wires during whatever their installation project entails.

Fault from Line to Ground is a situation where the Line or Hot wire touches ground in some way. This could be a nail through an electrical cable, an appliance that has gone faulty or a socket outlet that has shorted somehow. 

When there is a fault from line to ground there is often a massive electrical fault current that is generated and this is where we rely on the circuit breaker to turn the circuit off preventing fire, explosion, or electric shocks. 

Where the ground path is not of a low enough resistance, not enough fault current will be generated and the circuit breaker will not turn off leading to overheating and fire

Fault from Neutral to Ground is a situation where Neutral and Ground have interacted inside the electrical installation. This can result in a voltage appearing on the neutral wire and possible electric shock risk. This fault will not trip a circuit breaker but may trip an RCBO, RCD, GFCI or other earth fault detection device. 

This type of fault can go undetected in older electrical systems and will only come to light under electrical testing and when a new electrical panel or consumer unit is installed in the property. 

11) Ground Wire Pipe Clamps and Bonding Clamps

There are special clamps that are connected to pipework to ensure a good earth-ground connection and to make sure that the pipe does not become damaged during the installation or during the life of the clamp connection. 

These special clamps are designed to wrap around the pipe and hold on with tension almost like a metal zip tie. Clamps that use a screw to tighten on such as an earth rod or ground rod clamp should not be used on a pipe as there is a high probability that damage will occur to the pipe. 

The grounding wire should also be sized in accordance with the national electrical code or wiring regulations that govern the area. A newer home is likely to already have up to date grounding installed along with any other safety measure that is deemed necessary at the time of installation. 

An older home should have its electrical installation checked by a professional electrician to ensure that the wiring system, electrical panel, and electrical outlets are up to standard.

12) What about the Earthing Systems?

Across the world there are different types of earthing systems. WHAT ARE GROUND WIRES USED FOR in each one?

The ground wire is used to connect the Earthing of the property to the ground rod where a rod earthing system is used. 

The ground wire sometimes will enter the mains supply equipment where the electricity distributor provides the earth. This can sometimes connect to the neutral wire forming a combined neutral – earth conductor and sometimes the ground will be a separate wire all the way back to the supply transformer.

13) Electrical Inspection and Grounding Check

If your property is a little bit older and has not had the electrical system checked within the last ten years then you should have an electrical check carried out by a professional electrician. 

An electrical safety check is one of the best ways to check your wiring system is: 

• Up to date and; 
• To ensure that no-one is at risk of shock and;
• There are no electrical hazards.

14) Can Electrical Cables be Buried in the Ground?

Electrical wire can be buried in the ground but local wiring and building codes must be followed. The cable must be installed at a sufficient depth to foreseeably avoid and damage from digging tools or other external factors. 
Your local wiring code may also stipulate that some form of warning must be installed at a depth above the buried cable to warn anyone disturbing the ground in the future that there are wires buried and to take care with excavations.

15) Summary

Electrical ground wires are a vital part of every electrical system and their installation, maintenance and continuity should be checked regularly by a professional electrician with the right test equipment and knowledge to carry out the testing. 
Without electrical grounding, we put ourselves, out properties and those around us at risk so it is imperative that they work as intended when designed and installed.