The cable between the street and your switchboard is the one thing every other circuit in the property depends on. It belongs to you rather than to the network, and almost nobody has ever looked at it.
Pricing agreed before we start. We usually reply the same day.
The consumer mains are the conductors between the connection point and your main switchboard. That is the definition in the Service and Installation Rules, and it can be an overhead span from a pole, a cable trenched under the garden, or a run through the structure of the building. Whichever it is, there is only one of it.
The next line of the rules is the one that surprises people. The consumer mains form part of your electrical installation, which means they are owned and maintained by you rather than by the network. The distributor's responsibility stops at the connection point. Past that, the cable is a piece of your property that nobody inspects, nobody services and almost nobody has seen since the day it went in.
That matters because it is the bottleneck for the whole place. Every circuit, every appliance, every future plan for an electric car or an induction cooktop or a heat pump is drawing through that one cable. A switchboard full of modern breakers fed by original undersized mains is a very well protected bottleneck, not a solved problem.
And it is the part of an upgrade that people never think to ask about. The usual conversation is about the board, because the board is the thing you can see and open. The mains are behind the wall, or under the lawn, or up in the air, and they are the reason a quote comes back larger than expected surprisingly often.
"I need to upgrade my supply" describes three completely different jobs at three completely different prices. Which one you need depends on where the pinch actually is.
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What it means: the ratings here are illustrative rather than typical, and the point is the shape rather than the numbers. Whatever the property can actually draw is set by the smallest of the three, so widening any of the other two changes nothing at all. House 1 needs a cable. House 2 needs a board. House 3 needs the network, which is the slowest and least controllable of the three because it is not a decision you or your electrician get to make. Establishing which house you are is the first hour of the job and it is what separates a useful quote from a guess.
This is also why two quotes for the same stated problem can differ by thousands of dollars without either of them being dishonest. One has priced a new main switch, one has priced new mains under a driveway, and both were answering the question they were asked. The question worth asking instead is which of the three is the limit and how that was determined.
House 2 is the happiest outcome and it is more common than people expect, particularly in homes where the mains were renewed at some point but the board was left alone. It is worth ruling in or out before anything gets trenched, because a switchboard upgrade on its own is a fraction of the cost and a fraction of the disruption.
House 3 is the one to find out about early. Where the network supply itself is the constraint, the work involves the distributor, it moves on their timetable rather than yours, and no amount of good cable on your side of the connection point changes the answer.
Once for the current it has to carry, and once for the distance it has to carry it over. Whichever answer is larger is the one that gets installed.
The first calculation is maximum demand. The wiring rules set out how to work it out rather than leaving it to judgement, and for a domestic installation up to 100 amps per phase there is a table-based method that assigns a demand figure to each category of load: lighting, socket outlets, cooking appliances, water heating, air conditioning and so on. It deliberately is not the sum of every nameplate in the house, because nothing runs everything at once. Once there is a demand figure, the cable has to have a current rating at least that high after derating for how and where it is installed, since a cable buried in insulation or bunched with others carries less than the same cable in free air.
The second calculation is voltage drop, and it is the one people have never heard of. The wiring rules cap the total drop between the point of supply and any point of use at 5 per cent of nominal voltage. That budget is shared: the consumer mains spend some of it, the submains spend some, and the final circuit out to the appliance spends the rest. Common design practice is to allow roughly 2 per cent for the consumer mains, leaving the rest for everything downstream, though that split is a convention rather than a rule.
Voltage drop rises in proportion to length, so doubling the run doubles the drop. That single fact is why the same house on the same load can need a noticeably bigger cable simply for being set back from the street. On a short run, current decides the size and voltage drop is comfortably inside budget. Past a certain distance the two swap over, voltage drop becomes the binding constraint, and the cable that would have been adequate for the current is no longer adequate at all.
The North Shore produces this situation more than most parts of Sydney, because long driveways, houses set well back, and boards mounted at the street rather than at the dwelling are all common here. If your meter is at the front boundary and your switchboard is not, the run length is a real number in the calculation rather than a detail.
None of this is guesswork and none of it should be quoted from a phone call. It is a calculation with inputs: the demand, the run length, the installation method and the phases available. Anyone who can tell you the cable size before seeing the property is telling you what they usually fit.
The mains rarely fail outright. They tell you first, and the signs are easy to live with for years.
The lights dip when something big starts
An oven element, a ducted air conditioner or a pump starting is a sudden step in current, and the visible dip is voltage drop happening in real time somewhere between the street and the board.
A small flicker on a big motor is normal. A noticeable dip across the whole house every time the aircon kicks in is the mains telling you they are working harder than they should have to.
Discolouration or warmth at the main terminals
Browning, a smell of hot plastic, or a main switch that is warm to the back of the hand are all signs of a connection carrying more than it comfortably should, or of a termination that has loosened over decades of heating and cooling.
This is the one worth acting on quickly rather than monitoring, because the failure mode at that end of the installation is not a tripped breaker.
You have been told you cannot add the circuit you want
An EV charger, an induction cooktop, a second air conditioner or a granny flat all add real load, and a competent electrician who has done the calculation may come back and say the mains will not carry it.
That is not an upsell, it is the calculation. What is worth asking is which of the three constrictions failed, because the answer decides whether this is a cable job, a board job or a network job.
The mains are as old as the house
Rubber and fabric insulated mains from before about 1960 have usually gone hard and brittle, and early aluminium conductors bring their own termination problems where they meet copper.
Age alone is not a fault, but it does change the sensible order of works. If the mains are original and something else at the board is being replaced anyway, doing both at once avoids paying twice for the same outage.
Consumer mains work is priced by access far more than by materials, which is why the quote follows a site visit rather than a phone call.
The most common job on this page. New cable over the existing route, sized from the calculated demand and the run length rather than from what came out, terminated at both ends and tested before the supply goes back on.
Where the board is being altered at the same time, the two are quoted together, because the outage and the access are already being paid for once.
More civil work than electrical work. The cable is trenched at the correct depth with proper mechanical protection, and the route is what sets the price: a garden bed is cheap, a paved courtyard or a driveway is not, and mature roots on the North Shore are their own conversation.
The upside is permanent. No span across the yard, nothing for a tree to fall on, and nothing to be re-tensioned in twenty years.
Not every problem needs a new cable. A failed or overheating termination, storm damage to an overhead span, or a private pole that has deteriorated are all repairs in their own right.
Private poles catch people out: where the pole is on your land it is generally yours to maintain, which is not obvious from looking at it, and it is worth assessing while access is already set up.
Worth doing when the calculated demand genuinely approaches the ceiling, and worth resisting when it does not. Below 100 amps per phase the rules permit one, two or three phases, so for most houses this is a choice rather than a requirement.
Above 100 amps per phase, or where a motor exceeds 2 kW, three phases and neutral become compulsory and the decision is made for you.
The cable is inside your installation, but connecting and disconnecting it at the connection point is network side work, restricted in New South Wales to a Level 2 Accredited Service Provider. In practice both halves are done as one job by one provider, with the supply off at the property while it happens, and the network notified through its own channel.
Where metering is involved, and on a mains replacement it usually is, the retailer and their metering coordinator have to act as well. That is the same sequence set out on our meter box relocation page, and the same advice applies: the retailer's service order is what starts the clock and it is the one stage we cannot raise for you.
The maximum demand calculation and the cable selection are written down and handed over rather than kept in a head. If the property is extended, or another large load is added in five years, the next person starts from a number instead of starting again. We lodge a Certificate of Compliance for Electrical Work within 7 days of the compliance test, which since 1 July 2026 goes through the BCNSW eCert portal.
The cable between the connection point and your main switchboard. The Service and Installation Rules define them as the conductors between the connection point and the main service equipment enclosure, and they can run overhead, underground or through the structure of the building. The important part is the next sentence in the rules: they form part of your electrical installation, which means they are owned and maintained by you rather than by the network. Everything else in the property sits downstream of that one cable.
They are three separate constrictions in series and the narrowest one wins. Plenty of houses have a perfectly good supply from the street, adequate mains and a 63 amp main switch, in which case the board is the problem and the mains do not need touching. Plenty of others have a modern board fed by original undersized mains. Working out which is which before quoting is the whole job, and it is why two quotes for the same stated problem can differ by thousands of dollars.
Whatever the calculation says, which is why nobody can answer it over the phone. The cable has to satisfy two separate things at once. It must carry the maximum demand, worked out under AS/NZS 3000 using the Table C1 method for domestic installations up to 100 amps per phase, with the current rating derated for how and where it is installed. And it must keep voltage drop inside the 5 per cent the wiring rules allow between the point of supply and any point of use. On a short run the current decides the size. On a long run the voltage drop usually decides it, and it asks for a bigger cable than the current alone would.
Below 100 amps per phase you have a choice. The Service and Installation Rules allow one, two or three phases and neutral where maximum demand does not exceed 100 amps per phase, and require three phases and neutral above that, or where a motor exceeds 2 kW. So three phase is a decision for most houses rather than a requirement, and the honest answer is often that a properly sized single phase supply does everything the household actually needs. It becomes worth it when the calculated demand genuinely approaches the ceiling.
Not the whole job. The cable itself is inside your installation, but disconnecting and reconnecting it at the connection point is network side work, and in New South Wales that is restricted to a Level 2 Accredited Service Provider. In practice the two halves are done as one job by one provider, and the supply is off at the property while it happens. It also usually involves the retailer and the metering coordinator, in the same way a meter relocation does.
More civil work than electrical work, which is why it is priced the way it is. The cable is trenched from the connection point to the switchboard at a proper depth with the right mechanical protection, and the route decides the cost far more than the cable does. A garden bed is cheap. A driveway, a paved courtyard or mature tree roots are not. Where the pole itself is private property, its condition is worth assessing at the same time, because a private pole is the owner's to maintain.
Attending your job is a chargeable callout. We confirm what it costs when you book, and the price for the work itself is agreed before we start, so there are no surprises on the invoice.
Based in Castlecrag, covering all of Sydney. A few of the suburbs we work in most:
Related work: the board at the end of the mains is a switchboard upgrade, moving where the mains land is a meter box relocation, and which hot water system your supply can carry is covered on our hot water page. A board being rebuilt is the right moment for surge protection, and where the circuits behind it are as old as the mains, rewiring is the wider conversation. For apartment buildings, see strata electrical. See the full list of locations we service.
Upfront pricing, with the price agreed before we start. We work out which of the three is actually the limit before quoting any of them.
