ive just been to put some switch on at a house,there were no earth at them,there were wired in conduit,,pre 1960,,would an rcd on the mains protect the circuit
No. It could provide additional protection only. See reg 531.2.5. You sure the conduit isn't providing the CPC?
i've just been to put some switch on at a house ----------------------- I could understand this question coming from a diy'er but from the above it looks like you're doing this for a customer in which case you shouldn't need to be asking a question like this! This is one of the reasons part P and competent person schemes came about.
Check to see if you have an earth from the conduit, flying lead back to MET. If not no metal fittings!! If there is an earth, may be poor, then RCD would be better than a poke in the eye! 14th
And yet, if you put an RCD on that circuit you will be responsible for the compliance of that whole circuit to the 17th ED. You would therefore need to provide a CPC to all switches and accessories. You will be providing a certificate for your work too. If you replace the plastic switch with another plastic switch, you should warn the owner about the lack of earthing to that circuit and anything else that you happen to notice in passing. You would tell them that it is potentially dangerous if there are any metal fittings, also that the 45 year old wiring has reached the end of it's expected useful life and they should seriously consider replacing the installation. You would then take your money for replacing the switch and await their call for a rewire quotation... If your name lives up to it's suggestion, you would know this from your 2391 Inspection and testing course!
Government doccument the "Decent Home Standard" puts the life of an electrical installation at 30 years. food for thought....