Where is Cosine based and what areas do you cover?

Cosine Electrical is based at Waerenga in the North Waikato, between Te Kauwhata and Morrinsville. We cover the wider Waikato and South Auckland — from Manukau down to Te Awamutu, east to Thames, west to Raglan. Drive times from Waerenga: Hamilton 30-40 minutes, Cambridge 40 minutes, Pukekohe 30 minutes, Manukau 45 minutes, Raglan 75 minutes, Thames 60 minutes.

What is the digger operator on the crew thing?

Most electricians sub-contract digging for underground work — second contractor, second quote, second site visit. Cosine has a skilled digger operator on the crew, so for underground jobs we trench our own runs. One quote, one team, one site visit. Note: Cosine is not a registered drainlayer. Wastewater and stormwater scope sits with a licensed drainlayer.

How quickly do you get back with a quote?

Within 24 hours of the site visit. Itemised, in writing, valid 30 days. For smaller jobs we can often give a rough indication over the phone if you text photos of the existing setup.

What does a switchboard upgrade cost?

A straight switchboard upgrade in an average three-bedroom Waikato house is typically $1,500-$2,500 plus GST for board and labour. Push-ups: old cable failing insulation tests, mains upgrade needed (lines company involvement), asbestos in the meter-box backing board common in 60s and 70s houses. Everything flagged in the written quote — no surprises on the invoice.

What does an EV charger install cost?

Standard install with the existing switchboard up to spec is $1,200-$1,800 plus GST plus the charger. Older home needing a board upgrade adds $1,500-$2,500. Long trenched runs to a detached garage on a lifestyle block typically $2,500-$4,500 all-in.

Do you do compliance testing for landlords?

Yes — landlord WOF-equivalent inspections, RCD function tests, written reports with photos and plain-English findings. Insurance-ready paperwork.

Do you work with builders on renovations?

Yes — preferred sparky for several builders across Hamilton, Cambridge and Pukekohe. We walk through with the homeowner and builder before quoting, mark up the plans, and work to the builder's schedule. We don't hold up the next trade.

Can you handle commercial maintenance for property managers?

Yes — scheduled maintenance contracts, emergency callouts, fault-finding, compliance reporting. One number, one paperwork system, no padded packages and no lock-ins.

Do you certify the work?

Always. Every new circuit and every board upgrade gets a Certificate of Compliance emailed through within a day of the job finishing. Required for insurance, future sale and any audit.

What if you cannot fix a fault in one visit?

Some faults like earth leakage on a circuit shared by multiple cables genuinely need a second visit. Day 1 we isolate the faulty section onto its own RCBO so the rest of the house keeps power. Day 2 we test and replace the bad section. We don't punch holes in walls to brute-force the search.

Rental Property Electrical: What Waikato Landlords Actually Have to Do

Kris Goff

1 day ago

3 min read

Short answer: there is no single electrical warrant of fitness for a New Zealand rental. What there is: the Healthy Homes standards (heating, insulation, ventilation, moisture and draughts), the smoke alarm rules under the tenancy regulations, and the general duty to provide premises in a reasonable state of repair. Two of the three drive electrical work, and that work has to be certified.

Where electrical work comes into Healthy Homes

Heating

The main living room has to have a fixed heater that meets a minimum capacity worked out for that room. In practice that is usually a heat pump, and it usually needs a dedicated circuit. If the board is full or the mains are marginal, the heat pump job quietly becomes a switchboard job. Worth knowing before you get three quotes that do not mention it.

Ventilation

Kitchens and bathrooms need extractor fans venting to outside, at the required minimum sizes. Retrofitting a bathroom fan in an older place means a circuit, a duct run and a roof or soffit termination. Venting into the ceiling cavity is not compliant and creates a moisture problem that will cost you more later.

Moisture and draughts

Mostly not electrical - but sealing up an old open fireplace or blocking unused vents sometimes moves a wiring run, and underfloor moisture barriers turn up existing cabling that nobody has looked at in forty years.

Smoke alarms - separate rules, non-negotiable

Long-life photoelectric alarms with a 10-year battery, or hard-wired alarms.
Within three metres of every bedroom door, and on every level.
Landlord installs and maintains; tenant replaces dead batteries in the alarms that take them and must not disable them.
Keep the install date and the model on file. When an insurer or the Tenancy Tribunal asks, that record is the whole conversation.

Hard-wired interconnected alarms are not required in most existing rentals, but they are what we would put in our own place. If one alarm sees smoke, they all sound.

The things that are not on any checklist but end tenancies badly

No RCD protection. Common in pre-1990 rentals. Not currently mandated retrospectively, but it is the single cheapest safety improvement per dollar you will make on a rental.
Ceramic fuses. See the note on what a switchboard upgrade costs - old boards are an insurance conversation waiting to happen.
Outdoor socket outlets with no weatherproofing. Very common on rear decks.
Tenant-installed everything. Heated towel rails, outdoor lighting, spa pools. If it is hard-wired and you did not have it certified, it is yours now.

What to keep on file

One folder per property: smoke alarm install dates and models, the Healthy Homes compliance statement, and a Certificate of Compliance for every piece of electrical work done since you owned it. Our post on which electrical certificate is which explains what each document is.

Questions we get asked

Do I need an electrical inspection before every tenancy?

Not legally. But a periodic check on an older property, especially between tenancies when the place is empty, is cheap and it finds the things a tenant would never report.

The tenant says a socket sparks. How fast do I have to act?

Immediately. That is an urgent repair, and it is one of the few things where delay is genuinely indefensible.

Can I use the same heat pump quote for three properties?

The heat pump sizing is per room, and the electrical scope is per switchboard. Same brand, three different jobs.

Do you work with property managers?

Yes - scheduled maintenance, fault response and periodic testing across portfolios. See the commercial and maintenance page.

Getting a portfolio sorted

We cover the Waikato and South Auckland from Waerenga. If you have several properties, it is usually cheaper to do them in one run than one at a time. Call Kris on 021 466 666.