by ericmark »
Mon Jan 23, 2017 2:37 am
Looking at pictures it would seem simple answer is you can't use that lamp. In 1966 the rules on lighting changed, before 1966 there was no need to have an earth in lighting circuits, the introduction of metal light fitting specially fluorescent changed the rules.
Today one can still use the old system, there is no law saying you must up grade, however any light fitting used must be class II in other words designed to work with no earth.
I had this with mothers house, and I decided I may need to rent out her house, so cure was a re-wire so I could if required rent out her house. Before this I wanted lights for the kitchen, I paid some thing like £80 for a lamp which looked exactly the same as one costing £30 in B&Q just so it had the double square sticker saying it was class II.
The house had metal wall lights, fitted before 1966, which to my mind were too easy to put a hand on when putting coats on the coat hangers in the hall. And also an attempt to fit a consumer unit with RCD protection had failed, the RCD was forever tripping, so clearly there were wiring problems some where. So the re-wire gave me piece of mind.
Apart form the earth he wiring problem you have is common, we wire ceiling rose to ceiling rose which drops from ceiling rose to switch, this gives both advantages and disadvantages, easy to wire a ceiling fan or emergency lights, but there is no neutral in the light switch so there are also some down side bits. So we have an extra terminal in our ceiling roses, we have a permanent line as well as switched line.
Some times it's a simple case of swapping a three section connector block for a four section block to give extra terminal, other times using a junction box, there are some made specially for the job. Hager J501 is a good example of a lighting junction box which converts UK type wiring into EU type wiring used a lot for fitting down lights. The J804 is maintenance free, for use where only access would be to lift floor boards.
However in your case since you have no earth, these will not allow you to fit the lamp you have, you need a re-wire first. Also one of those black wires should have a red sleeve on it to show it's switched line not neutral.
So connecting the two reds together with a connector block and putting the two blacks one to line (L) the other to neutral (N) would make the light work, but without the earth wire it would not be safe, and since you don't know which of the two blacks is neutral and which is switched line you can't use any screw type bulbs, as the thread has to be neutral and you don't know which is which.
It also means you can't used metal light switches, and you need little plastic bungs to cover the screw heads for screws holding the switches in place, or plastic screws, or plastic back boxes. You could put a blob of silicon sealant on each screw, that would also stop anyone touching the retaining screws.
