Hi Guys

Let me start of by saying I am not an electrician :-)
Can anyone please give me some guidance on the below

Our contractor did an installation and used a 4 core armored cable. As it is a single phase supply, he used one of the cores as the earth. Our client has now rejected the installation as they say the Earth has to be a separate bare earth cable and we cannot use one of the cores.

In speaking to a few people I am getting conflicting information whether this is a legal installation or not.

Can anyone give me a definitive answer on this with reference made to a specific section in SANS so I can show the client