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.

Bore and Water Pump Wiring on a Waikato Lifestyle Block

Kris Goff

1 day ago

3 min read

Short answer: a bore or water pump supply is three problems at once - voltage drop over distance, motor protection, and getting the cable safely underground. Get the cable size wrong and the motor runs hot and dies early. Get the protection wrong and it dies suddenly. Get the trench wrong and you dig it twice.

Voltage drop is the one that catches people

On a lifestyle block the pump is often 40, 80 or 150 metres from the board. Over that distance a cable sized only for the current will deliver noticeably less voltage at the far end than at the board. A motor running on low voltage draws more current to do the same work, runs hotter, and its life shortens. It will not fail the day you install it. It will fail in year four and nobody will connect the two events.

The fix is boring and cheap: size the cable for the distance, not just the load. The extra cost while the trench is open is small. Replacing a submersible bore pump is not.

Protection that actually suits a pump

RCD protection. A pump in a wet pit or a bore head is exactly the situation RCDs exist for.
Correctly rated overload. Set to the motor nameplate, not wound up to stop nuisance tripping. A wound-up overload is a burnt winding on a timer.
Local isolation. A lockable isolator at the pump so anyone servicing it can make it safe without walking back to the house.
Low-water or dry-run cut-out. A bore pump that keeps running dry destroys itself. On tank systems, a float or level switch does the same job.
Sensible alarm or indication. Knowing the pump has tripped before the tank is empty is worth a lot on a Sunday.

The trench

Pump supplies nearly always mean an underground run, and usually one that crosses a paddock, a driveway or both. Cable buried at the depth AS/NZS 3000 requires, bedded properly, with marker tape above it so the next person with a digger finds out before the bucket does. Where vehicles or stock cross, it goes deeper and gets mechanical protection.

We have got a skilled digger operator on the crew, so we trench our own runs - one quote, one team, one lot of responsibility. While the trench is open it is worth laying a spare conduit for a level sensor cable or a future outside light. More on the underground services page.

Things worth doing at the same time

A weatherproof socket at the pump shed for a work light or a drill.
A light at the bore head, if you have ever tried to fix one at night.
Labelling at the board that says what the circuit actually feeds.
A written note of the cable size and route, kept with the house file.

Questions we get asked

My pump keeps tripping the breaker. Is the pump dead?

Not necessarily. It can be a failing capacitor, a seized impeller, water ingress at the terminations, or a genuine winding fault - and it can also be protection that was never right. It is a test-and-measure job, not a guess. The same approach applies as in our post on finding an RCD fault properly.

Can the pump share a circuit with the shed?

We would rather it did not. A pump on its own circuit means a shed fault does not leave you without water, and a pump fault does not take out the shed.

Do I need three-phase for a bigger pump?

Sometimes, and sometimes a variable speed drive gets you there on single-phase. Worth reading when a property actually needs three-phase before you apply for it.

Do you do the pump itself?

We do the electrical side - supply, protection, controls and certification. Pump supply and plumbing sits with your pump supplier, and we are happy to work alongside them.

Getting it sorted

Tell us the distance from the board, the pump nameplate, and what the cable has to cross. Call Kris on 021 466 666.