Here in Oregon(U.S.), there is electrical safety law that states that if there is previously installed wiring that isn't "up to code" and wasn't up to the code that was current when it was originally installed, then you can't add on to that circuit. So, when a portion of a circuit is extended by someone who doesn't do it right, and a contractor comes along later and extends it even more, then he is taking on responsibility for the reliability and safety of the previously installed work. So, he has to take time to check out the condition of the previous work, if he wants to stay out of trouble. This is a beginning step towards requiring electricians to responsibly inspect electrical installations, and not rely exclusively on the local inspectors, since a lot of work is performed by people who don't take out permits, and don't get inspections.
I worked on a job where the splices in every switch box and receptacle outlet box that I checked out were not crimped down properly -- the connections were all loose. I told the customer that there was a need for checking out all the splices in the house, and I got chewed out later by my boss for creating the impression that the house was unsafe, and that my comments put the electrical contractor I was working for in a difficult position.
It appears that the laws are trending towards increasing the responsibility of the installing electrician, and yet the real world conditions make it impossible for the electricians to protect themselves. I get the feeling that we all are assuming risks that we don't even know we are assuming.
As Bjarney mentioned, everyone and anyone who is involved in wiring a structure is likely to be sued...especially if they have 'deep pockets'. As Trumpy mentioned, there are contractors signing their lives away, not only in NZ, but also here in some of the States, via self inspections. To "do no wrong" is to have nothing to fear, but only if you have the money and time to press your case in court. No matter how innocent you might be, you still have to protect yourself and avoid dodgy installations like the plague! I guess it all comes down to making sure you have lots of documentation that precisely describes what portion of the wiring you are involved in altering, and a clear listing of materials used as well, signed by the customer. I don't think this will keep me out of court, but I hope it will make my defense strong enough so that I won't get dragged down by lengthy court proceedings.
For those who are not in the US, is there a requirement for upgrading (up to code, or in compliance with standards) any portions of the wiring which relate to what you might be called upon to work on?
