Rodza
If you are mostly doing "additions" i.e. new appliances into existing houses then it will all be high risk. You are only certifying PART of the installation i.e. the part you put in - and your overriding obligation is to ensure that nothing you do makes anything else unsafe. You need to do a COC for these, or else a combined COC GSC which is what our firm is doing for all of these sort of installations. Better safe then sorry.
You need to put the name and address at the start.
In the description be VERY clear about exactly what you have done. eg. Installed new Rinnai Infinity 24 LPG outside kitchen, with replacement LPG kit near corner of house and ran 20mm copper, surface mounted to position of new unit. Tested at 7 kPa - nil drop. Rinnai Infinity Serial Number is SN 13.11-xxxxxxx)
or
Install owner supplied Smeg gas hob. Ran new gas line 14 metres to join existing gas line on south side of house. Upsized gas main to 25mm. Tested at 4.5 kPa - nil drop.
Certified design - tick no unless you are following a design by someone like Becca Carter engineers etc, where you have been given a plan that you have to follow - in most cases for domestic this won't be the case.
The work does rely on manufacturer's instructions so in the two examples above (example 1 - Yes
www.rinnai.co.nz example 2 - yes
www.smeg.co.nzYes to AS/NZS5601.1 sections 3 to 6 or 5601.2 sections 3 to 9 (but mostly Section 1 I would think)
Are there any other standards for compliance - not usually in this instance
Next section is for an addition - is PART - and then describe the work you did
e.g. new Smeg hob (inset model number), 25mm gas main and new line to hob
e.g. Replacement LPG Kit in same position as existing was, and then new 20mm copper line out to Rinnai Infinity
Dates etc are self explanatory
PM me your email and I will send you a presentation that ESS did for a group of gasfitters in the Wellington region recently - it gives good examples.
When you go on line to file the High Risk they ask for slightly different information.
We are taking photos of the installations we do and attaching them to our records and also a sketch showing the pipe run, the size and type of pipe and the appliances installed by us.
ESS are primarily interested in safety, the Board will be using these certs no doubt as part of their audit.
Just describe what you do, ensure pipesizing is as per manufacturer's instructions etc and you follow 5601 and you can't go wrong.
We are charging $140 incl of GST for the GSC/COC combined.