Successive responses, which you have quoted at length, mention mechanical protection as being one of the uses. Yup - against plaster's trowel damage, not as per 522-06-07. The thread then goes on to mention the merits or otherwise of plastic Vs metal capping, and capping Vs oval conduit by the various contributors. Yup, within the context of why you'd use capping, i.e. trowel protection or providing a way to draw new cables through, not the merits of these methods as alternative ways to meet 522-06-07. Anyway. The only time I have EVER seen steel conduit in a domestic environment, is when a property has been converted from its former use as offices, or was a former school for example. You could come and see my house if you like - I've got it. And no - I didn't put it in, AFAICT it was done when the place was built. Any of the, old^H^H^H more experienced people here know how common it was in the 50's? BS7671 DOES NOT require the use of steel conduit as a prerequisite in domestic properties as far as I know. No - there are alternatives - IF you've got a cable which is not more than 50mm deep, OR in one of the acceptable horizontal/vertical routes, then I believe that the options are that the cable must: incorporate an earthed metallic covering complying with the requirements of the Regulations for a circuit protective conductor of the circuit concerned, or (ii) be enclosed in earthed conduit, trunking or ducting satisfying the requirements of the Regulations for a protective conductor, or (iii) be enclosed by mechanical protection sufficient to prevent penetration of the cable by nails, screws or the like, or (iv) be of insulated concentric construction. What joy, eh?
Aye, there's common sense, and then there's the Wiring Regulations. The best deterrent against damage occurring to pvc cables during plastering is to tell the plasterer that the cables are 'LIVE'. Tell them that you had to do this to provide power & lighting for the works to be carried out. The plasterers I have come across have a healthy fear of the unknown, and once infomred thus,they go to extra lengths to avoid the cables! TT