Hello all 

Received a fair bit of shocking news. Basically today I was out for my violin exam and therefore when I returned home, I received some shocking news!!

Electrician came to my house and discovered that our lighting circuit (not mains circuit) has no EATH/GROUND wire so therefore he will have to do a rewire job for the upstairs lighting circuit! And whats worse is that our light switches are made of metal

Flurofan96

Either rewire, or replace all luminaires to double isolated ones (i.e. anything with Plastic body like Fluorescent weather packs, or Metal too if all internal parts and wires have double isolation on them)

Same for the switches. Besides, check how they are made - In many types the Metal is only an outer layer on top of an otherwise fully Plastic body, so there isnt a way how voltage might come to it, except if there are Metal screws holding the faceplate to a Metal box behind the switch or the faceplate screw somehow punches the wire directly. See if the construction is proof from something like that

If all devices and wire isolation is in good shape everywhere, it is unlikely to make contact to the Metal enclosure of anything. Switches are simple devices and its not too hard to check that everything in them is done properly. For the luminaires i'd be not too concerned anyway, as you dont go up touch them all the time, and when you do you could as well flip off the switch. Its good to improve its safety to the proper level (either with Earth or with double isolation), but if you look in everywhere to check that existing isolation is ok and nothing rests on sharp edges of Metal or the like, then it is fairly safe and not like you all gonna die if you dont rewire it this second

I don't know about an un-grounded lighting circuit but I know you can change to three prong plugs on a two wire un-grounded circuit with out rewiring... 

So i don't think you need to rewire, you also don't need to replace fixtures, but electricians are in business to make money, so they often look at what makes them the most, in this case rewiring is the most expensive, so they should be able to pull out the code book and show you that a GFCI protected lighting circuit is not allowed.

But to change the plugs to a three prong type all you need to do is install a GFCI breaker to protect the outlet, and while they are costly, it's also allowed in code to install a GFCI plug offering downstream protection to additional outlets, and they are cheap if you hit up the restore, and they are mainly in colors like almond or brown unless your lucky but they work the same and they can go in there own box beside the breaker panel.

But you have to mark the downstream receptacles with the words “GFCI Protected” and “No Equipment Ground” if you change the two prong plugs to a three prong, the only time you have to rewire is if you do major renovations, and you can't extend an un-grounded circuit, so they only allow this to the existing circuit ...

So I don't see why you can't do this with a lighting circuit because it's a much lower risk then a receptacle circuit is.

This site has bit more info on the electrical / wiring / code side of things :> http://ecmweb.com/content/replacing-2-wire-ungrounded-receptacles
 

I don't know about an un-grounded lighting circuit but I know you can change to three prong plugs on a two wire un-grounded circuit with out rewiring... 

Connecting 3-contact socket on a 2-wire installation is highly unsafe, even with the GFCI (in most of the civilized world this is not allowed by the code - quite surprised to see the US code is actually allowing it).
The GFCI's are either not selective enough for a real fault (pure electromagnetic trigger; so less sensitive; 30mA and above) or not that reliable (electronic trigger, including phase filter to distinguish real fault from capacitive leak; 10mA and below).

Other problem is, most modern devices are allowed for grounded outlets only (see their manual; because they exhibit quite large ground capacitive leak, which will make rather high potential on accessible parts). The leak may be not dangerous for humans, but uses to be killing for the equipment itself, mainly for he signal interfaces (blown ports,...).

I think what the code is trying to address is a balance, while it might not be ideal, most people's only other option is to simply break the ground pin off there plug in order to plug it in which is even worse, and the code only allows it on existing wiring, and for some people rewiring is not in there budget so it's a compromise I guess. The code is only a minimum standard you can do more then code, I put up a 200 amp safety fused disconnect before my main panel my own meter socket and meter the inspector said I didn't need all that and passed it anyhow.. 

However for the most part if you don't go over about 250 feet of wire a 5mA GFCI will work fairly reliably in a general 110 volt household setting, but sometimes those homes with an old 60 amp panel will have half the house on one breaker so it doesn't take long to hit 250 feet which leads to nuisance tripping hence why I suggested putting all the GFCI plug by the breaker panel or use GFCI breakers so you know where to go to reset them (and try to get the ones with an indicator light on them so you know which one blew while your standing there in the dark)

But ya they are not as good as a RCD breaker on a 240 volt systems and for some yet unknown reason they are like 5 times the cost as well in north america, I can get a 63Amp one in the UK which will do an entire small home using 240 for less then a 15 amp 110 volt single circuit one over here, also why I suggested using a GFCI plug because they are  about 1/5 the cost of a GFCI breaker.. I also like the RCDs because you can adjust most of them so you don't get nuisance tripping, but that's not an option here in household equipment in north america...

Apparently back in the old days here in Australia many homes weren't wired with an earth/ground despite all sockets have an earth pin. From the things I've heard by the old electricans the sockets were wired with two core cable with the earth disconnected or with three core cable with the earth disconnected at the distribution board side. Fortunately I haven't come across this at all and have checked my house as well as my parents and my sisters since they are all fairly old. Luckily all the earths are connected and have RCDs.

Until the 1970s the two current carrying terminals of plugs and sockets here weren't marked with the polarity until the top left prong became the live and the top right became neutral.