This subject can be confusing if you are not a qualified electrician, and even then, there is some debate about whether you need an earth in a light fitting or a luminaire. Pre-1996 and, more pertinent pre-14th edition wiring regs stated that you did not need an earth. This was due to the post-war effort to build up sticks of raw materials.
This article will answer the frequently asked questions so you can confidently work on your home light fitting. Some of the information found is on the article do you need to earth my light fitting? by 1stelectricians.co.uk.
What does earthed mean in the UK?

It means if your home electrical circuit develops a fault, the electricity will discharge automatically to the earth via an earth spike that has been driven into the ground.
It prevents you from electrocution.
Do lights need to be earthed in the UK?
For electricians, you should always refer directly to the brown bible 18th edition, where you can find the updated regulations for you to comply with the wiring regulations.
Here is the answer to the question. If you have a lamp or light fitting fitted with a metal cover, say from the curling rose down to the light fitting requires you to have an earth. This type of light is known as a class 1 luminaire. The material is conductive and could cause a severe, if not fatal, electric shock.
If you have a light, a lamp or a light fitting that has a plastic ceiling rose or the main structure is made from a non-conductive material like ceramic. Then an earth is not required. This type of light is known as a class 2 luminaire.
How do you recognise what the protection level is on a light fitting?

There should be a symbol on the side of the light fitting or lamp., if it is new, the class should be marked on the packaging.
The symbols are:
Class one has the earth symbol, which requires the earth to be fitted. Class 2, a square within a square, does not require an earth to be fitted, and class 3 is low voltage that you may find on a CCTV circuit, which you do not need to consider.
Luminaire Class | Protection description | Applications |
Class I | Class I luminaries have essential insulation and grounding protection. Once the basic insulation fails, the grounding protection will stop any kind of mishap. | They are usually seen with sturdy plastic cases, such as street lamps, LED lighting poles, traffic lights, shell lamps, courtyard lamps, etc. These cases increase safety. |
Class II | This class has supplementary insulation, such as reinforced or double insulation, in addition to the primary insulation. | This is the kind of safety insulation found primarily on lamps and fixtures that people can touch more often, such as table lamps, portable LED fixtures, etc. |
Class III | The fixtures that use the SELV power supply (<50 V) are labelled Class III. These are highly protected because of the low voltage usage. | A high level of protection is used in areas where children are involved, medical devices, or work environments. |
What do you do if an earth wire comes from the ceiling?
If you have a class 1 light fitting, a terminal will be attached to the light fitting for you to attach the earth wire. It’s good practice to slide a piece of earth sheathing over the exposed wire.
For a class 2 light fitting, you can simply trim the exposed copper earth back and cover it with some insulation tape. Finding an exposed earth wire is expected because the installation electrician will invariably use twin and earth cables for the lighting circuit.
Do LED lights need to be earthed?

Yes, take caution with all light fittings. You are likely replacing incandescent bulbs or halogens with LEDs, and there is no difference in the power entering the light fitting, so ensure it is earthed correctly.
If a fault develops in the lighting circuit and your LED is not earthed, you could be in for a world of pain and hurt.
What colour is the earth wire?
Green and yellow, if you are unsure of the colours used in electrical wires, you need to find a local electrician to carry out your electrical work regardless of the size of the job.
What happens if you touch an earth wire?
When working with electrical wires, you should always be cautious and never assume anything.
Under normal conditions, you should not get an electric shock from earth wire. However, if conditions are not typical and there is a fault in the circuit, you could find yourself as the conductor of electricity to the ground, which will not be a pleasant experience for you.
Before you start work on any electrical circuit, regardless of your DIY experience, isolate the power from the consumer unit, aka the fuse board, and switch the main incoming power supply off at the big red switch. Don’t even rely solely on the RCBO circuit breaker.
What will happen if you don’t connect the earth wire to a conductive class 1 light fitting?
You are running a high-risk strategy of being electrocuted. You may decide you don’t have enough cable to pull through the ceiling to trim an earth wire for the connection, so decide to leave it.
Your light works fine, and nothing happens, and you and your family sit in the room night after night, oblivious to the ticking time bomb you have created.
Or
Over a period of time, your live wire works loose and comes into contact with the light fitting ( this happens, so don’t feel its pie in the sky), leaving your light fitting functional.
You or a family member decide to have spring cleaning and give the light a good dusting off after months of being used.
Now, as soon as the light is touched, 230 volts will run through your body to the ground. It can result in a terrible debilitating electrical shock, and worse, it can be fatal.
How can I prevent being electrocuted?

It is recommended in most cases to use a qualified electrician for all of your domestic electrical problems and wiring extensions. Your local electrician has trained for years through college and has practical experience being supervised constantly.
One of the biggest misconceptions is that qualified electricians work on live circuits. If you insist on DIY electrics, then the best way to prevent electrocution is to isolate the circuit. Your domestic installer will isolate circuits before he looks for a problem.
DIY enthusiasts should always be cautious when dealing with electrical cables and never assume the cable is not live until you have switched the main incoming power off at the consumer unit.
LED lights are somewhat safer to work with unless you put your finger into a live socket!