On a quotes I do for electrical works I am very glad I had, in the terms and conditions of the quote, the words -
'Any part of the existing installation which is to be added to or altered is assumed to be compliant with current SANS 10142 standards'
It can get you out of trouble if you find lots of problems once you start.
A job I quoted on looked neat, tidy and proper. I took a few covers off to have a look before quoting. The client wanted some alterations which were pretty standard. It's only when the faithful fluke 1653B was brought in we found SO many problems which caused the client to get upset and go after the guy who had done the original works.
We found that pretty much every single point had an earth wire in it, but stopped (cut) a couple of inches outside of the various points. You looked in the box and it looked new and neat, pulled the earth wire and found it was just there for show, just went into the conduits a little way and stopped. DB board the same!
Yes, he had a COC.
No, he was not happy.
No, I can't believe people would cut such corners to save a few bucks.