OP
Engineer54
But you have to be sure the conduit system meets the requirements of Reg 543.2.2, Reg 543.2.6 and reg 543.2.7
In a commercial/Industrial setting I would not rely on it due to the possibility of external influences damaging the conduit and perhaps causing a break in your protection, and most conduit systems in domestic premises from my experience years ago tends to be the old rolled type and is not continuous in a way that would satisfy the regs.
You've got to be joking here surely??
Industry and commercial installations have been relying on metal containment systems long before even i came into this industry. I was brought up on large industrial installations, where the whole kit and caboodle was metallic containment. Not a single CPC to be seen within those extensive containment systems, and not once have i ever seen a low, or loss of Zs values.
What is it with modern day electricians, thinking they know better than the long proven methods of providing more than just adequate protection, both mechanically and electrically?? I haven never seen a well designed and installed external galvanised conduit system circum to normal external influences, where it no-longer provided mechanical/electrical protection. Granted, in an environment where corrosive atmospheres are prevailing, standard metallic conduit would not be suitable. But in general terms, only MICC will out last a good galvanised containment system, ....and you can take that to the bank!! (or perhaps not in today's troubled times...lol!!)
Not all domestic installations used the old ''split conduit'' but i would agree with you, on your point concerning that type of conduit. The only modern day conduit system i would use a separate CPC, is the Yank EMT (think that what it's called) electrical tubing. That stuff relies on grub screws for it's connections!!