3 pin plugs vs 2 pin

[geofbob]

Why in the UK do we have complex 3 pin electric plugs with an earth and fuse (varying from 3 amp to 13), while on the Continent (eg France) they have simple 2 pin jobbies with no earth and no fuse. Is our system safer - in theory or in practice.

[geofbob]

And before Spellmaster ticks me off - there should be a question mark at the end of the second sentence!

[cupra]

In my experience, individual fusing of devices provides protection of both the device, and the associated cabling. i.e if a TV becomes faulty and draws too much current, the fuse should blow and prevent overheating of both the TV and the power cable. I'm not 'au fait' with overseas wiring regulations so I don't know how their protection is provided, but I doubt millions of Europeans have unsafe installations! By the way, their plugs can have an Earth connection - normally recessed on the top and bottom, although if the device being plugged in is 'Double insulated' then there is no need for an Earth connection.

[geofbob]

I should have made my question a little clearer - I know why we use a fuse in the plug; what I'm really interested in is why the French and other Continentals don't.

[cupra]

I've done a little digging - I believe that regulations in most Continental countries require circuit breakers for each room (or more than one room, depending upon the amount of outluts) - 6A for ungrounded outlets and 10/16A for grounded. They aren't wired as ring mains (unlike ours where there are two paths for the 13A supply) so if a fault occurs, it will isolate the room in question in the same way as our fuse isolates the device that is faulty. There's obviously pros and cons in both systems - interesting to find out though. (I've often wondered why most Hotels etc. on the continent have a distribution board for each room, so thanks for raising the question!)

[geofbob]

Thanks, cupra, that's just what I wanted to know. I didn't think the French would be more suicidal than us!

[tomr]

All cabling, irrespective of voltage or situation, must be sized according to the fault current that may flow. An earth connection is there to ensure that in the event of an earth fault there is a good return path and the maximum current can flow. This will operate any protective devices as quickly as possible. The fault current in a flex is a result of a problem with the appliance - it's dead already but save the flex from melting and causing a real hazard. Our ring mains are protected at 32A and have two legs (one each way round the ring) of 2.5mm which is more than ample for any fault current that may flow. By having plug top fuses we can have small flex on our table lamps and thick flex where required on an iron for example. The Europeans have radial circuits which are fused to protect the installation and the flex. I wasn't aware that they supply entire rooms off one fuse as Cupra says but this could be so. I am aware that they have different sockets according to the type of appliance that is going to be supplied, some with earths and some without. I think that our system is not only safer but also more flexible. Any of your sockets can be used to run any appliance that you own - from a portable welding set to a plug in air freshener and each has its full level of protection. Also, the descrimination of our fusing means that only the items that need a fault clearing will be interrupted rather than everything on a main. That, by the way, is why all (on that circuit) of your lights go out when a lamp pops because they aren't individually fused and the mcb takes them all out. Next time you replace a plug top fuse make sure that you choose the right size and don't just stick in a 13A!

[KARL]

As can happen in the UK some of the two pin/socket arrangements seen on the continent are out of date. Those that are up-to-date generally have earting possibilities. Those commonly seen in Germany have a recessed socket with two contactors on the inside surface which make contact with two similar conductors on the outside of the appropriate plug (but some plugs don't have these, as with double insulated items). One might think they are springs to hold the plug in place but their primary function is to serve as an earth connection. Other similar concepts can be found (as with rectangular section plugs in Italy) or ones where there is a three pin arrangement with the third pin in the socket rather than on the plug (as in France).
Various standards organisations (including the BSI from the UK) have met over the past decades to try and agree harmonising the various plug/socket arrangements, but so far they have made little or no progress. The characteristics of the powwer supply is for all intents and purposes identical throughout Europe and our equipment will operate happily everywhere. So why can't they agree a single standard on plugs/sockets ? None of those currently going are greatly superior to the rest.

[Tradesman]

There are very many socket and plug systems throughout the world ( don't go into the phone plugs as it gets even more bewildering). Our current plug was introduced in the 60s and is the safest in the world. the fuse is to protect the cable, the other systems use a cable per socket and the fuse is at a central place ( as a distribution board) not in the plug. When examining the UK plug there are millions of substandard plugs and fuses in use and for sale in the Uk. What can we do to stop them, usually turn a blind eye. Our plugs are rated at 13A but the fuse fitted should be for the appropriate appliance connected onto the plug.

[Bahbill]

Most of the answers already cover some of the points but non mention that a FUSE is a system protection device NOT specifically to protect a piece of equipment whether it be a table lamp or motor. It should, as already pointed out, be rated for the duty it has to perform bearing in mind the rating of the cable. Therefore the closer to the piece of equipment the better. The UK system of wiring is in my opinion the safest, the Earth Pin is the first to make and last to break. which should protect a person from electric shock should they remove the plug without first switching off at the socket (portable appliances). The fire risk is also reduced with the short distance to the fuse (better still with a RCCD fitted ) One more point to mention is that a 13A rated fuse does not operate (blow) at 13 Amperes but would take five and a half hours to melt at 1.3x rated current or approx 20 amperes. (and of course pro rata for the smaller sizes) Earthed and Unearhed, Grounded \ungrounded, systems are a seperate issue but BOTH can KILL. Having seen many types of system, I assure you that the UK one is the best in the world.

[Sky]

wow.. id never expect a question like that to get on the most popular list

[Gordon Rix]

As an electronic service engineer, the mains supply to my service bench is isolated from earth, to remove the risk of an electric shock via earth (which is connected to neutral at the sub station). Most people receive shocks by touching a live terminal and the circuit is completed by earth return via ground. So I'm absolutely astounded that the general opinion on here is that the UK system is superior as regards safety. I fully understand that if an appliance's metal casing should become "live" due to a fault ,with the UK system the plug top fuse will blow .But my point is if there was no earth connected at the sub station, you could safely touch that "live" appliance and not feel a thing!!! Believe me it's near bloody impossible to get a shock across live and neutral unless you're suicidle. When was the last time you heard of someone at a funfair that was electrocuted? that's because the electricity is supplied by local generators that are isolated from mains earth.

[cpso]

3pin plugs aremore safe

[Bahbill]

You can still get electrocted on an unearthed system!! If the Capacitance of the system is high enough there will be enough current 20 mA to cause fibrillation. Many ships run with the neutral unearthed but can still employ RCCDs for personnel protection as the capacitance of all the cables, motors and Generators to earth (ships hull) is more than sufficient to operate the standard 30 mA setting. Running with an unearthed neutral allows a phase to earth fault to be indicated without diruption of supply and hopefully located and cleared . However this does mean that the insulation on ALL equipment must be for full Line to Line voltage on a 3 Phase system. Taking the point of Fairground supplies, the capacitance is small and the voltage should be 110 v. Bahbill

[Quaye]

Yeah, the Lmaps are usually 110v and 12v/24v, the drive motors for the rides are mostly 3 Phase

[Quaye]

I meant Lamps (as in the Light Bulbs)

[old brick]

geofbob, i would like to know why some appliances have three pins while others have two?

[amy101]

Hi, can anyone advise me on a topic related to this question. I recently bought a brand new table lamp from Germany. It has the CE label, but has a 2 pin plug. Can I simply change the plug to a uk 3 pin? What about earthing it? Do I use a 3 Amp fuse? Would be very grateful for advice as I don't want to put myself in danger!

[New Forester]

Amy - If it's designed for 240 volt (which I think it will be), yes, you can just change the plug. Presumably it has an ordinary bayonet bulb? If the flex is 2-core, ignore the earth terminal. Brown or red to live, black or blue to neutral, green or green-and-yellow to earth. Use a 2 or 3 amp fuse for any light. And as Sylday says, you'd have been better off asking this as a new question...

[98fentons]

I think that just using either the fuse or the earth we are expecting trouble. By doing both we are pretty much guarenteeing that there shall be little or no accidents in the home.