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Misrated Fuse

Common PAT Testing Failures

Here are some examples of common PAT testing failures we find to give you an idea of what is deemed safe or not. It is important that the duty holder and end user have a basic knowledge of these items, so that any appliance that becomes unsafe between test periods gets removed from service and/or suitable repairs are carried out by a competent person.

Misrated Fuse

1. Incorrect Fuse Fitted

While there is an agreed standard for new electrical appliances, incorrect fuse ratings are still the most common issue found when PAT testing. With modern appliances anything that uses less than 700W of power should be fitted with a 3A fuse, anything above 700W a 13A fuse. While this works, and was designed to simplify the process, it’s not always adhered to and can be improved upon.

13A wall sockets are good for anything up to 3000W of power, therefore a general rule of thumb often applied is each 1000W draws approximately 4A of current, therefore needs a fuse rating slightly higher than that to protect the wire. In the event of an appliance entering a fault condition, a surge of current will blow the fuse, break the circuit and stop a too high current flowing down the wire. If the fuse rating is too high, it may not blow, potentially allowing a current too high to pass through the cable, which left over time will cause a fire.

How is it corrected? Your PAT test engineer will replace the fuse with the correct rating and your appliance will be safe to use.

2. Cracked or Damaged Plug

Damaged Plug

Any cracks or damage to the plug, or excessive damage to the appliance itself that may expose it’s electrics will fail. A cracked or damaged plug, could potentially be an electric shock risk when the end user is removing or plugging in the item. A cracked case that exposes the electrics inside, would also be a fail for the same reason.

How is it corrected? A cracked or damaged plug would be replaced by your PAT test engineer. An item with a damaged case will most likely need replacing, insulation tape is not an acceptable repair. If spotted before your PAT testing is due, they should be repaired or removed from service.

3. Non-Insulated Live and Neutral Pins

Non-insulated Live and Neutral Pins Despite not being manufactured in this style for many years, these plugs still crop up from time to time. Newer, modern plugs have the Live and Neutral pins insulated to stop the users fingers making connection with the metal when the plug is partially inserted, during plugging & unplugging of the appliance. Whereas if the plug and socket is the correct size and shape, the user shouldn’t be able to make contact with the pins until they have been disconnected from the source, there have been instances where people have used metal implements to remove a stuck plug and made contact. A common trick amongst school children was to wedge a 1p piece between the pins to create an explosion when plugging in – this is a very unsafe practice, potentially injuring the user, causing a fire and damaging the whole electric circuit. These plugs are very dangerous if used incorrectly and should not be used.

How is it corrected? These will be replaced by your PAT test engineer. If spotted before your PAT testing is due, they should be repaired or removed from service.

4. Earth Pin Insulation

Insulated Earth PinAs a complete opposite to the above problem, the plug attached to the cable to the left has the earth pin partly insulated that it shouldn’t have. We’ve covered this before on our Counterfeit Plugs blog post so have a read of that if you want details, but when this is plugged in, it won’t make the earth connection as required.

How is it corrected? These items are generally counterfeit cables, stamped as meeting the BS1363 when they don’t. The plug cannot be swapped as there is no way in telling if the rest of the cable has been manufactured with sub-standard materials. You should remove them from service, contact the supplier who you purchased them from for a full refund, and inform trading standards.

5. Damaged Flex

Damaged FlexExcessive wear and tear to the cable is also considered dangerous and the item should be removed from service if spotted. If any more damage was to occur to the flex in the image, bare wires would potentially be visible, creating a shock risk if the wire, or a conductive item that made a connection to the wire, was touched.

How is it corrected? In nearly all cases, damaged flex can be disconnected from the appliance and refitted with a direct replacement, or one with a heavier-duty sheath.

Counterfeit Plugs

Counterfeit Plugs

It seems that a suspect batch of counterfeit plugs has entered the UK market. Many of us will have been stung online before with counterfeit goods, either from internet auction sites or other outlets but it’s not the branding that is in question with these items – it seems they have been molded as BS1363 (the British Standard for a normal 3-pin plug) but don’t meet the requirements. If you have recently had your items PAT tested then you should be fine – an experienced PAT tester would pick up the problem at the visual inspection stage, failing that the lead and plug would fail the earth bond test. It is easy to spot when you’ve seen one – the earth pin (the longer pin at the top of the plug) is half insulated (see image below).

Counterfeit Plugs
Earth pin (on the right) is part insulated.

To meet the British Standard, this can be fully plastic for Class 2, non-earthed appliances – you may have mobile phone chargers and other low-voltage power supply units like this – but for all other appliances it should be solid brass with no insulation. The live and neutral pins are supposed to be insulated, this is to protect the fingers as the plug is removed – the pins will be disconnected from the mains (connection is made at the back of the wall socket) before the user can touch any metal part. However the earth pin connects at the front of the socket. This is so that when the appliance is being plugged in, it is earthed safely before the live and neutral pins are connected and current begins passing through the item. It remains safely earthed until after the live and neutral pins are disconnected when unplugging the item. If the above lead was to be plugged into a wall socket, the metal earth connectors inside the socket would be touching the plastic insulation, not making an earth connection as required.

BS1363 IEC Lead
The earth pin on this IEC lead conforms to the British Standard and would make a safe earth connection

Why is this important?

In the event of a problem with the appliance, such as a connection between a live wire and a metal part of the appliance, the earth pin is designed to make sure the current flows safely to ground, and that the user isn’t at risk of getting an electric shock. The insulation on the earth pin will break this ‘safety circuit’ and the metal parts of the appliance will potentially be carrying a live electric current.

What should I do about it?

The easiest thing to do is get staff to double-check all your equipment. A quick visual inspection will find the problem. In the event you find any items with semi-insulated earth pins, remove them from service immediately. If you know where that particular lead has been purchased from, contact the retailer for a full refund. Trading Standards should also be made aware if you think the retailer/manufacturer is knowingly selling these counterfeit items. IEC (kettle leads) cables that supply power to many appliances, such as PCs, monitors and printers are the most common kind found. Do not attempt to repair with a replacement plug as other sub-standard materials may have been used in the production of these items.

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