Not sure what motivated the change - but as plumbing and gasfitting have certifying status - maybe they thought drainlaying needed it.  It will separate those that design and build from those that carry out the instructions of the person who designs the system.  Certifier will now be the only ones able to sign of consents with the Council where previously obviously licensed drainlayers did.  The system worked pretty well as it was - but someone somewhere obviously thought it was necessary. 

i guess to a certain extent the difference is or rather was the common paper - being more business and employer safety orientated - yet they are now doing away with it

i do believe that to own/operate business some form of training or certification should be required ie a cert in business management or similar (what was covered in common was ideal IMHO)

thunder what sort of work do you partake in? you are designing what you install? are you talking about residential plumbing?

Sorry integrated talking about plumbing your first post was correct.
We focus on high end residental and have done multi rise apartments in remuera but most is high end residential work with a sprinkling of maintance/trouble shooting work lightly basted with some commercial factory work.
Plumbing/gas/drainlaying is pretty much the same in theroy...What comes in must go out!...But most of the larger plumbing jobs that i have worked on plans have been drawn up by a hydrolic enginer...but its not too hard you have to factor in proabible demand/ discharge and venting requirments for the type of installation the theroys the same between the three trades and i guess thats why they do plumbing and gasfitting combined i would love to see plumbing and drainlaying combined as a course...But i have never meet a sole drainlayer/gasfitter lol do they exist?

"being more business and employer safety orientated" ...that is a good point what other trades require people to study about business before being able to gain full qual?

Im sort of glad that they have done away with this part...because when the time comes for me i will do my own study on bussiness and employment laws/theroy...When the time comes so the info is new and up to date.
I would be very happy if they drew a clear distinction between licensed and certifying status by installing some more unit standards to learn then i would see clear deffinition between these two stages...maybees a solar course or a multirise design course...just something that says im still climbing the ladder...but just to say there is one exam on what already i should have been taught and a two year stand down time to gain final qual just doesnt sit right with me...but thats just my view.

Sorry if its a bit confused i blame it on the empty bottle of steinlager next to me.