Yes, yes, yes you do.  Firstly if you are not a signed up apprentice then you need to apply for an exemption to work in plumbing - if a signed up apprentice then part of the signing up involves getting  a trainee licence. 

As an exemption holder you must work under THE DIRECT SUPERVISION (which is IN THE EYESIGHT, AND EARSHOT of a certifying plumber) for TWO YEARS, then you can work under the DIRECTION of a certifying plumber.  The certifier must do all testing.

As a trainee for the FIRST year you must work under THE DIRECT SUPERVISION of a certifying plumber.

Do not put yourself at risk.  In the end it is not your employer who will go down the gurgler over this - it is you as an individual who is responsible.  You should not be working on your own at this stage at all.  Visit www.pgdb.co.nz to view the rules around supervision.  There are brochures that are available.

It is always a hard one because you are probably wanting an apprenticeship and do not want to rock the boat, but if you stuff up and the person puts in a complaint to the PGDB they could prosecute you through the district court.  You would not be charged through their disciplinary system because you are unlicensed.

An exemption license is $100.00 and needs to be signed off by your supervisor.  You will probably need to pay the licence yourself.  You should not be on a training wage unless you are a signed up apprentice, therefore you should not be paid less than the minimum wage.

Experts
Each of our tradesmen is a certified and qualified expert in their field

Excerpt from Blue Cross Plumbers website (as at the bottom of your sign off) - hmmm if you work for them they might also be breaching the Fair Trading Act if they are representing you as a certified and qualified expert in your field....

Hi Chilly - actually they can prosecute employers, but usually the easiest and most clean cut prosecution is the person who actually did the work without a licence.   Everyone with a licence needs to educate those without licences of the legal requirements.  The more we ignore those who do not have  a licence, the more we water down these trades.  It is a regulated industry - and many have fought hard to keep it so - therefore there needs to be a licence or exemption in place to work in it.  I am appalled by some employers who exploit these young people in the trade and do not tell them about their obligations.