However, as you can see from these photographs, the slot also allows access to contact the live part of the socket using our needle test probe. 

To understand this better, we have cut away a cover to show a view of what is going on under the dome. You can see that the cover plate only makes contact with the socket around its edge. internally there is a space between the surface of the socket and the underside of the plate, this space, combined with the chamfered edge of the socket hole , allows free passage for the probe to be inserted alongside the live pin. (The edge of the pin holes are chamfered to allow plugs to be inserted easily, this chamfer is just enough to guide the probe.)

This cover, obtained from IKEA, is called PATRULL.
The cover plates are quite flexible so it is very easy to push in upside down. 

None of the pins are the correct size.

The close-up picture below shows the pin ends. 
BS 1363 requires that the end of the earth pin is cleanly chamfered on all 4 sides, as in the LH example which is a real plug with an insulated earth pin. The shorter pins should be chamfered only on the long sides as the brass pin shown. The IKEA cover has no clean chamfers, just generally rounded ends.  

The socket shutter mechanism is designed to work with the proper pin shape and correct length. An incorrect shape can place undue stress on the socket contacts, and the short length results in the cover being pushed back out of many sockets.

Those we bought were in a packet bearing a photo of a US socket cover on the front, but the basic design of the plate indicates that it was originally for continental sockets (they are made in Holland). It appears that in adapting it to fit a UK socket the “power pins” have been placed right at the edge of the plate, (BS 1363 requires pins to be 9.5 mm from the edge). As a result the sockets are not completely covered leaving an unshuttered hole into which a paper clip or similar can be inserted, making direct contact with a lethal 230 volts! (see picture below)

The internal shutters of a BS 1363 socket are there to prevent such foreign bodies being inserted, and it is not possible to do this in the absence of a cover.

Later versions of the IKEA cover have been modified. But, instead of making the the plate extend to the full 9.5 mm from the pin required by BS 1363, it is now just under 2 mm! This is just enough to cover the hole when the cover is fully inserted, but the hole becomes visible again when the cover “pops out” due to its short pins (the pins have been extended slightly, but not enough to prevent the pop out problem in all sockets). The pins remain badly shaped and the wrong thickness.

The red version appears to be intended for use as an extractor for the white one (although we found they were easy to remove without), a pictogram on the packet warns not to put it in a socket, but dimensionally it is identical. We think the red colour makes it particularly attractive to small children.

Ikea claims their cover “Reduces the risk of children sticking a finger or an object into a wall socket.” 
We think that the opposite is true.
Ikea also states “Can be used in both earthed and unearthed sockets.”
They seem unaware that an “unearthed socket” would be illegal in the UK!

Mothercare sell, under their own brand, the same design that IKEA does. Those we bought were a shiny grey colour which we think would attract children, but Mothercare currently only offer a white version on their website.

This image (left) of the white version was taken from Mothercare’s own website, it shows a cover that does not fully cover the socket holes!
None of the pins are the correct size.

It has all the same problems as IKEA.

When we first saw pictures of this model from Emmay Care we thought that it was another re-branded IKEA/Mothercare type. But, they have managed to modify the design to make it even worse and introduced even more problems! 

Emmay Care has made the cover plate slightly SMALLER all round, and that means the lower socket holes are even more exposed! All three pins (which were already too short in IKEA/Mothercare) have been made EVEN SHORTER! They have similar badly formed ends.

To make matters worse they have reduced the width of the earth pin to be the same width as the power pins!!! The function of a dummy earth pin is solely to open the shutters in a socket. If the earth pin is not wide enough, the shutters will not open far enough as the picture below shows (we cut the cover in half so we could insert only the earth pin).

You can see how the shutters are only half open, so when the lower pins are inserted they crash into the shutters and over time this will cause wear (made worse by the badly shaped ends). 

Not only will this cover make your sockets dangerous, it may cause damage!

Removing the cover is made much easier for a child because the short pins mean that the cover will be partly pushed out of many sockets as shown on the left. (We call this “pop out”) A child will find no difficulty using that gap at the bottom to remove the socket cover.

Having removed the cover the child may easily put the Emmay Care cover into the earth contact only in the inverted position, leaving the live contacts exposed to children, just like every other cover that we have tested,

To understand the “pop out” effect we partially cut away the housing of this socket (left). You can see that because the pin is too short for the straight part to properly engage with the contact it is been partially pushed back out, leaving a significant space between the cover plate and the socket. You can read more in our fact sheet “Does size matter?”

The photo on the right shows how a needle or paperclip can be pushed directly into the live contact because the Emmay cover has disabled the shutters when inserted, but does not properly cover the holes. The automatic shutters are there to prevent this happening, by inserting this cover the socket is made dangerous!

This is the Lindam cover which we bought at Homebase. We have also seen it offered by Argos and Babies R Us, as well as through Amazon and eBay.

This model also has a split earth pin, but without the feature which causes the model above to lock. It does allow deeper insertion upside down, but does not always open the shutters completely, it is too narrow for that. However, they are opened far enough to allow access to the live contact!

Every pin is the wrong size and the ends are badly shaped.

The non-standard earth pin does not open shutters properly in normal insertion, so the other pins have to be forced past the shutters with a danger of excessive wear to the socket.

The cover shown was found in a hall used by a playgroup. The cracks you see were present when it was found and they allow the earth pin to be fully inserted, upside down, without difficulty.

In September 2009 we found the identical model on sale in Tesco, labelled: “TESCO MY BABY'S SOCKET COVERS”,
In July 2010 we found the same covers advertised as “Ladybird” by Littlewoods, Woolworths and other “Shop Direct” companies.

The pins are too short, and have been tapered to assist with insertion, because they are actually placed too close together! The result is that it is fairly difficult to remove but it is always buckled because of the incorrect spacing. this places a stress on the insulated case of the socket with potential long term damage.
This cover should never be inserted in a socket!

This is the “masterplug” brand socket cover purchased from Woolworths.

We also purchased some from B&Q under their own brand.

On our Videos page is a video showing how Luca, an 11 month old baby, removes this cover with ease in under 3 seconds!

This model is less flexible but still opens the shutters when put in upside down.  

None of the pins is the correct size.

This is the “Safety 1st” branded cover which is available from a number of stores, we bought this one in December 08 from B&Q.

It is the only cover we have seen with all pins made to the correct size, although the ends are shaped wrongly.

This cover is one of the easiest for a child to to remove, as it is equipped with the most accessible finger grips we have seen! They are perfectly positioned at top and bottom, allowing a child to use both hands to remove it.

It is sufficiently flexible to be easy to insert upside down, leaving the shutters open and the live contacts exposed.

We purchased this model, marked PMS through Cablestar, an online supplier, via Amazon. Cablestar became the first retailer to cease selling covers when we brought the danger to their attention. The packet was labelled “Mercury Telecraft Ltd.”  The PMS cover has the shortest lower pins we have yet seen at less than 2/3 of the standard length! They do not reach the contacts. The earth pin length is correct, but it is 10% thicker than allowed by BS 1363. This will almost certainly damage sockets and result in a real plug making an unsatisfactory earth contact, which is very dangerous. The short pins make it particularly easy to insert upside down.
We have also seen this model on sale at Maplin under their own brand, as well as numerous other brands including “Eurosonic” and (from Amazon) “Status”. The “Status” packet is illegally marked “CE”, “BS5733” & “BS1363”, these marks are mutually exclusive, and non actually apply (there are no such markings on the product).

We purchased this model in a local hardware store. It was sold under the brand name Deanston Electrical (a distributor). We have also seen it in a number of other smaller hardware stores.

The same model is also packaged by another distributor under the RED/GREY Electrical Accessories brand.

All of the pins are of incorrect length, and they are also all too thick. Being too thick makes it a little more difficult to remove, but can also cause long term damage to a socket.

The cover is easy to insert upside down.

It is also the most brittle that we have encountered. The earth pins of the two samples we tried both snapped when inserted upside down, the failure being at the root of the pin. This means that removal of the broken pin is extremely difficult without appropriate tools, and the shutters will remain open until the pin is removed or the socket replaced by an electrician.

The “power pins” are excessively thick, so in sockets where “pop out” does not occur they will cause long term damage to the contacts, this could lead to overheating and possible fire.

This is the rear view of a partially disassembled typical socket. 

The shutter mechanism can be clearly seen, an earth pin has been inserted into the socket on the left, the shutters which normally cover the power sockets have opened. There is nothing inserted on the right and the shutters are closed.