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.

Dairy Shed Electrical: The Pre-Season Checks That Stop a 4am Breakdown

Kris Goff

1 day ago

3 min read

Short answer: a milking shed is the hardest electrical environment on most Waikato farms - constant moisture, wash-down chemicals, vibration from vacuum and milk pumps, and everything running twice a day. The breakdowns are nearly all predictable. Earthing, motor starters, the vat and chiller circuits, and the wash-down zone are where to look before calving, not during it.

Why sheds fail where houses do not

Three things a house never has to deal with. Moisture gets into enclosures that were fine when they were installed and are now twenty years old with a perished gasket. Wash-down chemicals attack terminations and gland seals. And vibration from pumps slowly backs off connections that were torqued correctly on day one. None of these are dramatic. They just accumulate until the day a pump will not start with a full yard of cows outside.

The pre-season checklist

Earthing and bonding

Stray voltage is the one that ruins a herd's behaviour before anyone works out why. Cows are far more sensitive to potential differences than people are, and a shed with degraded bonding can make them reluctant to enter the yard or let down properly. Checking earth continuity and bonding across the plant, the yard rails and the water lines is the single most valuable half hour of the year.

RCD protection and the board

Farm sheds often have boards that grew by accretion - a circuit added here, a starter added there, half of them unlabelled. Get it tested, get it labelled, and get RCD protection where it belongs. If the board is at the end of its life, do it in the dry months, not in August.

Motor starters and overloads

Vacuum pump, milk pump, wash pump, effluent pump. Check contactors for pitting, check overload settings actually match the motor nameplate, and check that nobody has wound an overload up to stop nuisance tripping. A wound-up overload is not a fix - it is a burnt motor scheduled for later.

Vat and chiller

Milk cooling is the circuit where a fault costs you a grade, not just an hour. Check the supply, the isolation, and that the chiller controls are on a circuit that is not sharing with something that trips.

Wash-down zones and IP ratings

Anything in the wash-down area needs enclosures and fittings rated for it, with glands done properly and lids that still seal. A $30 enclosure with a cracked lid is how water gets into a $3,000 starter.

Lighting

Corroded batten fittings over the pit are a standing nuisance. Sealed LED fittings rated for the environment pay for themselves in not going back.

Backup supply

If a rural outage during milking is a real risk on your farm, a generator changeover arrangement needs to be installed and certified, not improvised with a lead. Doing it properly also protects the linesmen working on the network, which is the part people forget.

Questions we get asked

When is the best time to do this?

Late in the dry period, before calving. You want the board work done when a shutdown costs you an afternoon rather than a milking.

Can you do it around milking?

Yes. Most shed work gets done between milkings or in the dry period. Tell us the window and we will work to it.

Do you do the trenching for a new supply to a shed or pump?

Yes - we have got a skilled digger operator on the crew, so underground runs are one quote and one team rather than coordinating a digger contractor yourself. More on the underground services page.

Do you cover our area?

We are at Waerenga in the north Waikato and cover the dairy country from Te Kauwhata and Huntly across to Morrinsville and Paeroa, down to Cambridge and Te Awamutu, and north to Tuakau and Pukekohe.

Book the pre-season check

Call Kris on 021 466 666. If you want it on a schedule rather than remembering each year, we can put it on a maintenance run - see the commercial repairs and maintenance page.