Class of Protection in Electrical Appliances

March 24th, 2021 by dayat No comments »

All electrical appliances using mains voltage have to provide at least 2 levels of protection to the user. This is to ensure that if one of the protection layers were to fail, there is the back-up of the second layer still in place. This makes electrical equipment very safe to use. Appliances can be Class 1 or Class 2.

When PAT testing, it is important to first identify the Class of the appliance as Class 1 appliances are tested differently from Class 2 appliances.

Depending on how exactly the protection is provided, electrical appliance are put into 5 Classes of equipment construction which are Class 1, 2, 3, 0, 01. Of these the most important are Class 1 & 2. For completeness all the Classes are described below.


Here the protection is provided by a combination of insulation and use of the mains Earth. It is best shown by referring to an electric fire that has been taken apart.

In the open plug the three wires connecting to the LIVE, NEUTRAL and EARTH pins. Inside the fire, the brown LIVE wire and the blue NEUTRAL wire connect to a plastic connector. The green/yellow Earth wire connects to the metal case of the fire.

The user is protected from electric shock by the plastic insulation of the connector. This holds the LIVE and NEUTRAL wires in place and prevents them from touching the metal case of this electric fire. This plastic insulation of the connector is known as basic insulation.

If this basic insulation were to fail, say due to excessive movement of the cable where it touches the metal case then the user of the fire can receive an electric shock if not for the fact that the EARTH wire is present.

By connecting to the metal case of the electric fire, the EARTH wire keeps all this metal at EARTH potential. What this means is that it is impossible to get an electric shock even when the metal case of the fire is connected directly to the LIVE voltage. In practice a fuse would blow either in the plug or the main fuse box to protect the user.

In summary, in Class 1 appliances the user is protected by a combination of basic insulation and the provision of an EARTH connection, thus providing two levels of protection.

When PAT Testing Class 1 appliances, the Earth Continuity and Insulation Resistance tests are carried out.


In a Class 2 appliance, the user is protected by at least two layers of insulation. For this reason, Class 2 appliances are also known as Double Insulated. They do not require an Earth connection.

This is best shown by looking inside a Class 2 electric drill which has been opened up. Inside one can see that as well as the plastic connector providing basic insulation, there is additional insulation provided by the plastic enclosure of the drill.

The user is therefore protected by two separate layers of insulation. When PAT testing Class 2 appliances, just the Insulation Resistance test is carried out.

Class 2 appliances are always indicated by the double box symbol on the rating plate.


Equipment built to Class 3 standard are designed to be supplied from a special safety isolating transformer whose output is known as Safety Extra-Low Voltage or SELV. This must not exceed 50 V AC and is normally is below 24V or 12V. All Class 3 appliances are marked by a special symbol. There is no use of an Earth in Class III appliance

The electrical safety of Class 3 appliances are taken care of in the safety isolating transformer design where the separation between the windings is equivalent to double insulation. The transformer is marked as being suitable for use with Class III appliances.

CLASS 0 & 01

This type of equipment is not for normal use in business or residential environments. It is just presented here for completeness.

Class 0 appliances depend only on basic insulation for protection from electric shock. For this reason, they do not have 2 levels of protection built in and are not allowed for sale. The brass lamp shown here is an example of a two wire, metal cased appliance with only basic insulation. There is no provision for connection of an earth to the bulb holder.

In Class 01 appliances, there is provision for an Earth connection, but it is wired with either twin core cable or only has a 2-pin plug, so an Earth cannot be connected. AS in Class 0 equipment, one is dependent only on basic insulation for protection from electric shock. As they only have 1 level of protection, Class 01 appliances are not allowed for sale.

If during PAT testing one comes across a Class 0 or Class 01 appliance these can be failed.


As the PAT testing carried on Class 1 and Class 2 appliances differ, it is important to identify one from the other. There is no other area of PAT testing that causes more confusion than this and there are many myths surrounding this. It will be informative to list some of these.

If there is a fuse in the plug, then it must be Class 1.

It is made of metal so it must be Class 1

The case is plastic so it must be Class 2

It has a three core cable so it must be Class 1

The plug has a metal Earth pin so it must be Class 1

None of the above statements is a fool-proof way to identify Class I and Class II appliances and some are quite misleading.

The easiest rule to apply is the one below.

If the rating plate has a double box then the appliance is Class 2. If it does not then it is Class 1.

Example – Kettle

The rating plate on this kettle clearly has no “double-box” symbol, so using our rule, it must be Class 1. The Earth connection from the plug is terminated on the outside metal casing of the heating element. When PAT testing this kettle the Earth Continuity and Insulation Resistance test has to be carried out.

Example – Plug-top power supply

The rating plate on this Plug-top transformer clearly shows the “double box” symbol, so this is a Class 2 appliance. Note that it has a plastic Earth pin, as this is not required for Class II. (Not all Class 2 appliances have a plastic earth pin). Just the Insulation Resistance test has to be carried out during PAT testing.

Example – Mains extension

The rating plate on this extension is moulded in the plastic. It clearly does not have a “double-box” symbol, so it must be a Class 1. When PAT testing this extension lead the Earth Continuity and Insulation Resistance test has to be carried out.

Example – Table lamp

The rating plate on this table lamp clearly shows the “double-box” so it is a Class 2 appliance. (Note that this is a Class 2 appliance that is largely in a metal enclosure). The bulb holder is made of plastic and provides the required double insulation. Just the Insulation Resistance test has to be carried out during PAT testing.

Example – Desk fan

The rating plate for this fan not only does not have a “double-box” symbol, it also says that the appliance must be earthed. So this is clearly a Class 1 appliance. Note that it does not have any user accessible metal.

Example – Metal Lamp

If this metal lamp had a rating plate, then it would be a Class 1 appliance as it has an earth point on the lamp holder. However, as the rating plate is missing, this would have to be failed.

Are Class 1 and Class 2 appliances just as safe?

As both have 2 levels of protection built in, they are both safe for general use.

However with Class 1 an appliance, one of the layers of safety is provided by the earth connection. For this to be effective, the wiring in the building has to be inspected regularly to check that the Earth in the mains socket is correctly taken to the local earth potential. This is usually picked off the Earth sheathing of the mains cable coming into the premises, or by driving a local stake into the ground. So Class 1 appliances depend on the external wiring in the building to fully provide the 2 levels of protection.

Class 2 appliances however always provide 2 levels of protection irrespective of the status of the wiring installation. Both layers of protection are built into the design making Class 2 appliances are a lot safer than Class 1 appliances.

Appliance Repair Needs, Shops and Warranties

February 24th, 2021 by dayat No comments »

Home appliances are becoming so ingrained inside our lives that individuals never even give them another thought – till they break down. The amount of comfort they offer is something that almost all people prefer to quickly leap over to the telephone for the nearest, local appliance specialist shop the moment there’s a dilemma. Being so acquainted with appliance the appliance since it is not functioning could leave us with an unforeseen and pretty pricey position.

Before proceeding with do-it-yourself techniques, first determine if the appliance is still under a warranty or agreement. Just in case you decide to repair the appliance while it’s still under warranty, you’ll instantly void the warranty. Any Brand Appliance repair can inform you just in case your appliance remains not functional rather it is outside or inside the warranty period. Just in case you approach this appliance repair situation on your very own, listed here are a couple of fundamental steps for reference to begin the process:

1. Contact the organization that you bought the appliance from. For individuals who’ve kept their receipts handy, this may help greatly.

2. Contact the organization that provides the warranty or inquire with the place where you first bought the appliance from to retrieve the warranty information from.

3. Be sure to thoroughly read over the warranty to be absolutely sure you have all the information you will need to file the claim.

4. Request additional information regarding the kinds of repairs needed for the appliance. Are you currently responsible for getting in contact with an specialist or do they have recommended repair shops that they require the appliance to be taken to?

5. Ensure that you keep any receipts to ensure that you will be properly returned for the costs that you just incurred regarding the appliance repair.

Typically, appliance repair companies have specialists available that may fix most household appliances. Major equipment repair companies will typically make service calls to your home. Modest home appliances are often fixed in-house within the specialist shop location, instead of within your house. Even if it’s a little appliance, you have to be certain they offer repair or alternative services in addition having a warranty or guarantee for services(s) made.

After selecting a few appliance or specialist shop companies, you’ll have the ability to ask any type of questions like the following below:

1. What is your first availability to repair the appliance? Can you ensure the guaranteed arrival of the service technician or will someone call before coming to my residence?

2. Will I need to bring my appliance in for repair at your shop or will someone come to my residence to complete the repair?

3. Is there a warranty or some form of guarantee offered on work completed and/or on the parts used in the repair?

4. Will there be an upfront cost for the appliance or specialist shop service call as well as an itemized estimate given before maintenance of the appliance or will all charges be totaled when the appliance is fully repaired on the final bill?

5. If your appliance is a product which utilizes gas, electrical, radiation and/or refrigeration, please keep in mind that qualified repair specialists must have previous experience with gas, electrical, and refrigeration issues. Just in case you’re going to get any kind of appliance repair issues fixed, it is of the utmost importance to be sure that a qualified home appliance person repairs the appliance.

6. If the financial costs of the appliance are more than what you can afford, Be sure to ask questions regarding a layaway or monthly payment plan. Additionally, you may choose to inquire about a monthly service repair plan with the appliance repair company. By obtaining a monthly service repair plan, you can be sure that a qualified appliance specialist will be available to help prevent undesirable breakdowns and malfunctions. Building a relationship with a reliable appliance repair company provides you with a sense of satisfaction for your major home appliances and all your home appliances protected under one convenient repair plan. You may even seek their professional advice when purchasing new products knowing that you have an honest opinion from someone you trust and could rely on before, during and after the home appliance purchase.