What Is a Certificate of Compliance (COC) in New Zealand?

If you've done any prescribed electrical work in New Zealand, you already know the certificate has to happen. What's less often explained clearly is what that certificate actually represents, and why the industry treats it as such a firm requirement rather than a nice-to-have piece of paperwork.

What a COC actually certifies

A Certificate of Compliance is a record, issued by the electrical worker who carried out the work, confirming that the prescribed electrical work they completed has been done safely and complies with the applicable requirements. It's a self-declaration from the person who did the work, tied to their own registration, for the specific work they personally carried out.

An Electrical Safety Certificate (ESC), which we'll get to below, is issued by the same worker in the same way. The two aren't a two-tier, "worker signs one, someone else signs the other" system, they're both the worker's own certification, just covering different kinds of work.

Who can issue one

Only a registered electrical worker can issue a COC, and only for work that falls within their own registration and practising scope. It's tied to the individual, not the business they work for, which is why the certificate carries the worker's own registration number rather than just a company name.

When one is required

As a general rule, a COC is required after prescribed electrical work is completed, with a small number of low-risk exemptions. In practice, that means most jobs a licensed electrician does on a residential or commercial installation need one issued at completion, not weeks later once someone in the office gets around to it.

That timing matters more than it might seem. A COC issued on the day, while the details of the job are fresh and the client is still on site, is a more accurate and more useful record than one reconstructed from memory a fortnight later.

COC vs ESC: what's the actual difference

This is the bit that trips people up, so it's worth being precise: it isn't about risk level, and it isn't about a second, independent person checking the work. Both a COC and an ESC are completed by the same electrical worker who did the job. The real question is whether the cabling structure changed.

An ESC applies where no structural change has been made to the cabling, a straight like-for-like replacement. Changing a damaged power point for an identical one, or replacing a light fitting like-for-like, are typical ESC jobs. No new wiring has gone in, but the work still needs to be certified as safe and compliant, and that's exactly what the ESC covers.

A COC covers prescribed electrical work where the cabling itself has changed, new wiring has been run or installed. The quick test: has the worker installed cabling, or altered the wiring structure in any way? Wiring and installing a new light fitting where there wasn't one before needs a COC. Wiring and installing a new power point needs a COC.

A lot of real jobs need both at once: new wiring goes in (the COC-triggering part), and it all has to be signed off as safe, checked and tested to the applicable code (the ESC part). That's why the two are so often issued together as a single Combined COC + ESC, one document covering the installation work and the safety sign-off together.

Why it matters to the client, not just the regulator

For a homeowner or business, the COC is proof the work was done by a registered professional and meets the applicable safety requirements. It commonly comes up again at property sale, during insurance claims, or any time someone needs to show that electrical work on the property was done properly, sometimes years after the job.

That's the other reason issuing promptly and keeping records properly matters: you don't know today which certificate a client is going to need to produce in five years' time, so every one has to be right, and it has to be findable.

Where things commonly go wrong

The same handful of problems come up again and again: certificates that don't get issued until well after the job, descriptions of the work that are too generic to actually stand behind later, and paper copies that go missing in a folder somewhere between the ute and the office. None of these are compliance failures at the point the work was done, they're record-keeping failures that surface later, usually at the worst possible time, like when a client is trying to sell a property and can't produce the certificate.

This is exactly the gap digital certificate tools are built to close: issue the COC on site, on the day, with a clear description of the actual work, and store it somewhere it can be found again on request, not just filed and forgotten. That's the whole premise behind CertMate, we built it because we were the ones chasing our own paper trail.

Want to see how CertMate handles COC issuing on site, from filling in the details to a client-ready PDF in minutes? Start a free trial.