can you certify an installation which has two core red and black singles wiring in conduits approx 50 years old with no cpcs

Question

the clients expect me to certifcate an installation with red and black singles cables in conduit thats approx 50 -60 years old with no cpcs 
 my take is i cannot touch this with a barge pole 
 
 dave O'Malley

broadgage · Accepted Answer

It MIGHT be acceptable, It was permitted and is still permitted to use the conduit as the CPC, provided that a suitably low earth loop impedance is achieved. There should be flyleads from earth terminal in the box to the earth terminal of the accessories. Metal fixing screws will often provide acceptable earth continuity but it is poor practice to rely on this. 
 If the single core live and neutral wires are still in good condition and are PVC or polythene insulated they should be fine for continued use. If the wires are rubber/cotton covered than they are probably due for replacement.

mapj1 · Answer

What sort of Zs reading do you get from the far point(s) ? If the conduit is rusted out and you can see the singles, or if there is no earth connection to the far end, then it has probably had it. 
 However properly jointed conduit can act as the CPC and with PVC insulated singles can last more or less for ever, and a little surface rusting need not immediate condemn anything. The red and black is neither here nor there, but the state of the insulation is - any chance of a photo to set the scene ? As noted already perished rubber would be a failure, but PVC is likely to be OK unless overloaded, and even waxed cotton if the ends are in good condition, may well be OK for another half century. 
 Are you doing an EICR or actually working on it to add extra points etc ? 
 Mike.

can you certify an installation which has two core red and black singles wiring in conduits approx 50 years old with no cpcs

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