Plug Lock
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Q What country's does the plug lock work in ?
A Any country that uses a standard BS1363 plug which are the United Kingdom, but also in Pakistan, Ireland, Sri Lanka, Maldives, Bahrain, UAE, Qatar, Yemen, Oman, Jordan, Cyprus, Malta, Gibraltar, Botswana, Ghana, Hong Kong, Macau, Brunei, Malaysia, Singapore, Indonesia, Bangladesh, Kenya, Uganda, Malawi, Nigeria, Mauritius, Iraq, Kuwait, Tanzania, Zambia and Zimbabwe. BS 1363 is also standard in several of the former British Caribbean colonies such as Belize, Dominica, St. Lucia, Saint Vincent and the Grenadines and Grenada.
Q What is a BS1363 plug ?
A BS 1363 is a British Standard which specifies the most common type of domestic AC power plugs and sockets. The standard was introduced in 1947, shortly after the Second World War, as part of a new standard for electrical wiring in the United Kingdom.
Q Why do we have a earth pin ?
A Unlike most other types of sockets, the earth pin is necessary for use of the BS 1363 plug, as it is needed to push open a shutter in the socket to allow the line and neutral pins to be inserted. It also polarizes the plug, ensuring that the line pin is connected to the correct terminal in the socket. Moulded plugs for unearthed, double-insulated appliances may substitute this contact with a non-conductive plastic pin to open the shutter. Most non-fixed domestic equipment is connected using the BS 1363 plugs, the main exceptions being equipment requiring more than 13 amps.
Q Is this plug safe to use ?
A Yes of cause, we only use the earth pin to lock the plug into the socket. The earth pin is ONLY used in a fault condition to earth and the components we use to lock the earth pin to the socket are non conductive.
Q What are the pin dimensions of the plug, is it the same as a normal plug ?
A Yes it is, the line and neutral pins have a rectangular cross section 6.35±0.13 mm wide and 3.975±0.075 mm height. They are 17.7±0.5 mm long and their centre lines are horizontally 11.115±0.065 mm on either side of the symmetry plane of the plug. The protective-earth pin is centered on the symmetry plane, is 22.73±0.5 mm long and has a cross section 3.975±0.075 mm wide and 7.925±0.125 mm height. The centre lines of the line/neutral pins and the protective pin are vertically 22.23±0.13 mm apart. For more information click HERE.

(These dimensions may be more easily remembered in the original imperial units, which are not mentioned in the current standard: 1/4±0.005 inch wide by 5/32±0.0025 inch high, and 0.695±0.02 inch long. They are 7/8±0.005 inch horizontally from each other, and the same distance vertically from the earth pin, which is 0.895±0.02 inch long. The pin lengths were presumably originally 0.7 and 0.9 inches, and assigned an asymmetric tolerance of +0.005/−0.015.)

Q Does this plug have a fuse fitted ?
A Yes the plug has a fuse inside. The fuse is required to protect the cord, as British wiring standards allow very high current ring main circuits to the socket. Accepted practice is to choose the smallest standard fuse (3, 5 or 13 A) that will allow the appliance to function. Using a 13 A fuse on an appliance with thin cord is a fire hazard. The fuse is 1 in (25.40 mm) long, conforming to standard BS 1362. Sockets are required to be wired with neutral on the left and live on the right (viewed from the front of the socket) so that the fuse in the plug disconnects the live feed if it blows. The same convention is used for all British sockets connected directly to "mains" wiring.
Q Will the two earth locking pins obstruct the socket plastic shutter ?
A No, UK wiring regulations (BS 7671) require sockets in homes to have shutters over the live and neutral connections to prevent the insertion of objects other than electric plugs. On most designs, these shutters are opened by the insertion of the longer earth prong. On some designs they are opened by the simultaneous insertion of the live and neutral prongs of the right shape and spacing. The effect of the shutters is to help prevent the use of plugs made to other standards, and to prevent children and others poking things into the dangerous connections. On plugs for Class II appliances that do not require an earth, the earth pin is often plastic and serves only to open the shutters and to enforce the correct orientation of live and neutral. It may be possible to open the shutters by putting a screwdriver blade into the earth socket, so as to insert a Type C Plug (but not the BS 4573 UK shaver) or other plug types, but this can be dangerous for such plugs will not have a fuse and will often not fit properly.

BS 1363 plugs and sockets started appearing in 1946 and BS 1363 was first published in 1947. By the end of the 1950s, it had replaced the earlier type D BS 546 in new installations, and by the end of the 1960s, most earlier type D installations had been rewired to BS 1363 standards. Outlets usually include switches on the live side for convenience and safety.

Q What is earthing ?
A Earthing refers to connecting the exposed conductive part of electrical equipment and also the extraneous conductive parts of earthed bodies like water pipe to the general mass of the earth to carry away safely any fault current that may arise due to ground faults. This is done to minimize the danger of electric shock due to human contact with live parts which could result from bad insulation and insulation failures.In domestic wiring earthing of equipment is done by bonding together the earth points and metallic parts of the appliances and earthed bodies using Green/Yellow wire coming from the consumer main earthing terminal. The earth terminal is in turn connected to either consumer’s earth electrode (TT system) or to the earth point given by the supplier (TN system).
Q So what would you use the locking plug for ?
A Well any appliance that you do not want power removed from or any socket that you don't want anyone to use (use cord outlet blanking plate if not attached to an appliance) or to isolate fault appliances so that they can't be inserted into a socket. Some examples can be a fridge freezer, UPS power supply for IT systems, hospital critical appliances, network routers, public show rooms, airport waiting lounges, slot machines in game arcades, schools (where children are present), hotel rooms to secure the appliances, the list is endless.
Q Current legislation requires that in the event of emergencies, electrical flow must be able to be 'cut off', so the plug can't be removed, so how can you comply with the current regulations ?
A Well you still have access to the socket switches to switch off the plug. If its connected to a non switched socket (NOT RECOMMENDED) then the fuse will blow or the main MCB will trip in a fault condition. We recommend you use the lock my plug in a switched socket outlet.
Q What happens is there is a fault on the appliance, as it can't be removed ?
A The internal fuse will blow inside the plug or if its connected to a RCD socket (recommended) then the 30ma trip will operate protecting the appliance. You can then remove the lockable plug by turning the disc on top of the plug and once removed you can then unplug the appliance, unscrew the cover of the plug and lift it off. Prise the fuse from its clips and insert a new one of the correct amp rating. Refit the cover.
Q What about BS 1363-1 clause 12.9.1 ?
A This clause states "All exposed surfaces of plug pins shall be smooth and free from burrs or sharp edges and other irregularities which could cause damage or excessive wear to corresponding socket contacts or shutters.”  - The earth pin does not have any parts protruding when being inserted into the socket, and if the plug was in the lock position it could not be inserted into the socket anyway. So the plug does comply with the above regulation.
Q Consider the case of a person attempting to remove a plug in case of emergency. Let us assume that the person who has identified the emergency is not familiar with the fact that a non-standard plug is in use, they grasp the plug tightly and give it a strong pull to withdraw the plug. In this situation your device could cause the partial destruction of the face plate, and that face plate is a primary protective part designed to ensure that live parts remain inaccessible!
A No this is not possible, the rubber pins only protrude 1mm each side of the earth pin, and the damage will be to the plugs earth pin at the top and bottom. The plug top does have a lock and unlock indication and is designed to stop people removing the plug, and if they do remove it with force then it will damage the rubber pins. I would imagine that the word LOCK on the plug top with a arrow pointing to it, would suggest the plug is locked into the socket and when it does not pull out of the socket easy, then i would imagine the person will stop pulling at the plug.
Q You should also bear in mind that there are a number of variations on the way in which shutter mechanisms operate, no assumptions should be made beyond
1) the shutters opening on the insertion of some combination of pins as determined by the standard, and
2) the automatic closure of the shutters when the plug is withdrawn.

It would seem probable that an attempt to withdraw a plug which had obstructions protruding from the earth pin would be likely to cause permanent damage to those mechanisms which rely on a cam operated by the earth pin. Such cams are designed to yield to pressure from outside the plug, but not from inside.

A The plug can't be withdrawn until the 2 off 2mm locking pins have been withdrawn back into the earth pin. No damage will occure as the plug will not be able to be removed. Once you turn the plugs top disc to the unlock position then the plug can be withdrawn with no permanent damage to any mechanisms. Also the pins are rubber and this wont damage any sockets.
Q What fuse size do i use ?
A These days all appliance plugs contain cartridge fuses, normally rated at 3, 5 or 13 amps depending on the wattage of the appliance.

For example, ohms law says that I (amps) = W (Wattage) / V (voltage 240V)
So if you have a 3KW electric kettle this is 3,000 watts so if you divide by 240 volts which in the UK is the standard house voltage you get 3000/240 = 12.5 amps, so you need a 13 amp fuse in your plug socket.

Enter the appliance wattage (3KW = 3000 Watts) and press calculate to get the amps value:

Watts (vA)         Amps (I)             

  • Appliances rated up to 700 watts should be protected by a 3 amp fuse.
  • Appliances rated 700–1200 watts should be protected by a 5 amp fuse.
  • Appliances rated 1200–3000 watts should have a 13 amp fuse.

Always check the appliance manufacturer’s instructions as there may be exceptions to this general rule. When you buy a new plug it will usually contain a 13 amp fuse; this may be too high for your appliance. Never fit a fuse with the wrong rating.

Q What's the correct way to wire a 3 pin plug ?
A Below are two pictures, the wrong way and the correct way.
3 pin plug Incorrect way 3 pin plug Correct way
Q How do i fit your Plug lock to my appliance ?
  1. Unscrew and remove the cover of the old plug. Turn the plug over and loosen the terminal screws so the flex cores can be pulled from the pins. Slacken the screws securing the flex clamp and pull the flex free. If the appliance was working, prise out and keep the fuse – but don’t re-use it without checking it is the correct rating for the appliance.
  2. Feed the end of the flex under the flex clamp of the lock my plug. Connect the brown core to the terminal ‘L’ on the right as you look down on the plug (this will have a clip for the fuse). Connect the blue core to the terminal ‘N’ on the left. Connect the green/yellow earth core to the terminal ‘E’ or at the top (the longest of the three pins).
  3. Make sure that the earth wire is longest and the live wire shortest – this way if the plug is ripped off the flex, the live wire will break away first and the earth last. If there is no earth core (the appliance is double-insulated), simply make sure that the terminal screw is tight.
  4. Check that the cores are pushed fully home with the insulation right up to the terminals and tighten all the screws. Confirm the rating of the fuse and replace it with one of the correct amp rating if necessary. Tighten the flex clamp screws to grip the flex firmly. Finally, screw on the cover, ensuring that it fits properly all round.
Q What flex size do i use for the size of the fuse ?
A Up to 700 Watts use 0.5mm squared cable, 700 Watts to 1400 Watts use 0.75mm squared cable, 1400 Watts to 2300 Watts use 1mm squared cable and above 2300 Watts to 3000 watts use 1.5mm squared cable.

Flex Sizes