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.

New Build Electrical: The Waikato Timeline From Slab to Sign-Off

Kris Goff

1 day ago

3 min read

Short answer: on a typical New Zealand new build the electrician is on site three or four times - temporary supply, pre-wire before the linings go on, fit-off after painting, and connection and certification at the end. Nearly every decision that costs money to change is made before the pre-wire.

The four visits

1. Temporary supply

A temporary builder's supply so the site has power for the trades. On a rural site this is sometimes the same trench and the same application as the permanent connection, which is worth planning together rather than paying for twice.

2. Pre-wire

Framing is up, roof is on, linings are not. Every cable for the whole house goes in now - every socket, switch, light, data point, oven, hob, heat pump, and anything outside. This is the visit that decides how the house works for the next thirty years, and it happens before there is a single wall to help you picture it.

3. Fit-off

After linings, stopping and painting. Switches, sockets, light fittings, the switchboard, the heat pump head units. Fast, if the pre-wire was right.

4. Connection, testing and certification

Permanent supply, meter, full testing, Certificate of Compliance and the Record of Inspection where the work requires one. That paperwork goes to your council file and your bank, so it is not the bit to leave loose.

Decide these before the pre-wire

Where the furniture goes. Sockets follow the bed, the couch and the desk. Walk each room with the plan and place them.
Kitchen appliance schedule. Oven, hob, dishwasher, waste disposal, rangehood, and where the microwave actually lives. A late appliance change is a wall opened up.
Heating and cooling. Heat pump positions and their circuits. Underfloor heating in bathrooms has to go in before the tiles.
Outdoor. Lighting, sockets on the deck, spa, gate, shed, irrigation, and the EV charger even if the car is three years away. A conduit while the ground is open is almost free.
Data. Wired points to the TV, office and the router position. Wireless is fine until it is not.
Switchboard location and size. Leave spare ways. You will use them.

The cost of changing your mind

Before pre-wire: a conversation. During pre-wire: minutes. After linings: a wall gets opened, patched, stopped and repainted, and the painter comes back. The same socket can be $40 or $400 depending only on when you asked for it. That is why we would rather spend a long time on the plan than a short time on the pre-wire.

Working with your builder

We work to the builder's programme, not around it. Pre-wire has to happen in the window between the roof going on and the linings going up, and if we hold that up we hold up the whole job. Tell us the dates early and we will be there. There is more on renovation and new build work on our renovations page.

Questions we get asked

How many power points should each room have?

More than the plan says. Doubles are barely more expensive than singles at pre-wire, and nobody has ever complained about too many. Bedrooms want them at both sides of the bed; the lounge wants them where the couch actually goes.

Should I put in an EV charger circuit now?

Run the cable, even if you do not fit the charger. The cost while the walls are open is a fraction of the retrofit, and it is a selling point later.

Who deals with the lines company?

We do, alongside your builder. The connection application goes to WEL Networks, Waipa Networks, Powerco, Counties Energy or Vector depending on where you are building, and those timelines are longer than people expect.

Do you do the trenching for the supply?

Yes. We have got a skilled digger operator on the crew, so the driveway run and the supply trench are one quote rather than a separate digger contractor. See the underground services page.

Starting a build

Talk to us at plan stage, not at pre-wire stage. Call Kris on 021 466 666.