Building a Granny Flat on a Narrow Inner West Block? Here's What the Electrical Connection Actually Involves

Building a granny flat on a narrow Inner West block? Here's what the electrical connection actually involves. A secondary dwelling almost always needs its own metering and, in most cases, its own sub board fed from a new or upgraded consumer mains run, and on a tight terrace block that's usually the hardest part of the whole job to plan around, not the electrical work itself. Here's what actually determines whether it's straightforward or genuinely tricky on streets like Marrickville, Dulwich Hill, Petersham, Leichhardt and Summer Hill.

⚡ Quick Answers: Granny Flat Electrical Connections on Narrow Blocks

• Does a granny flat need its own switchboard? Usually yes, a separate sub board fed from the main property's supply or a new consumer mains run, so the secondary dwelling has its own isolation and protection.
• Can it share the existing meter? Sometimes, but most owners choose separate metering so the granny flat's usage is billed independently, particularly if it will be rented out.
• Will the block's narrow width cause a problem? It can, mainly around where the new sub board and cable run physically fit, and whether there's side access at all. This is a site assessment question, not a rule that rules it out.
• Does an old terrace's existing supply need upgrading first? Often. Many Inner West terraces are still on a single phase supply sized for one household, and adding a second dwelling's load can mean assessing whether that capacity is genuinely enough.
• Do I need a new private power pole for a granny flat? Rarely on the Inner West's typical narrow blocks. Underground consumer mains from the existing point of attachment is almost always the practical option here rather than a new pole.
• What paperwork is involved? A Notification of Service Work, a Certificate of Compliance for Electrical Work, and network approval for any new or altered connection point, all handled by your electrician or Level 2 ASP.

1. A granny flat counts as a second electrical installation, not an extra circuit

It's a common assumption that a granny flat just needs a few extra circuits run off the main house board. In practice, the Service and Installation Rules of NSW treat a secondary dwelling as its own installation, in the same category as a duplex unit, which means it typically needs its own point of isolation and, in most cases, its own metering. That distinction matters early, because it changes the scope from "add some power points" to "plan a proper second supply," and that's the piece worth getting right before a granny flat design is finalised, not after.

2. Why narrow Inner West blocks make the cable run the real planning question

On a standard suburban block there's often clear side access to run new consumer mains from the point of attachment to a rear granny flat. Plenty of Inner West terraces, particularly the older workers' cottages and narrow-fronted rows around Marrickville, Petersham and Leichhardt, don't have that luxury: the gap between the house and the boundary fence can be barely wide enough to walk through, let alone trench or run conduit. This doesn't make the job impossible, but it does mean the cable route, whether that's along a side passage, through a shared right of way, or via the rear lane, needs to be worked out at the site assessment stage, not assumed from a plan.

3. Single phase capacity is worth checking before you commit to the design

A lot of older Inner West streets are still supplied by a single phase network connection sized decades ago for one household's typical load. Adding a granny flat, especially one with its own kitchen, hot water and reverse cycle air conditioning, can bring the combined household closer to what that single phase supply can comfortably carry. This doesn't automatically mean an upgrade to three phase is needed; plenty of granny flats run comfortably on a shared single phase supply with the right sub board sizing. It does mean a proper load assessment belongs early in the process, well before tradespeople are booked, so the design isn't fighting the supply capacity later.

4. Where the new switchboard actually goes

Every switchboard needs enough clear space around it for safe access, a domestic board generally needs at least 0.6 metres of unobstructed space in front of it under AS/NZS 3000, which sounds generous until you're trying to find that much clear wall on a granny flat with a tight footprint of its own. Getting the sub board position right the first time, rather than bolting it wherever there happens to be a spare wall, avoids a compliance headache and a harder to use board down the track.

5. Metering: shared, sub-metered or fully separate

There are three real options for a granny flat's electricity: share the main meter and split the cost privately (simplest, but rarely ideal if it's rented separately), install a sub meter for internal cost tracking while staying on the one supply point, or install a genuinely separate meter and connection point so the granny flat is billed independently by the retailer. Most owners planning to rent the granny flat out choose full separate metering. It costs more to set up, but it avoids ongoing disputes over usage and keeps the arrangement clean if the property is ever sold or the granny flat tenanted long term.

6. When a private pole genuinely is the answer, and when it isn't

Some Inner West properties, particularly those on rear lane blocks or battleaxe style lots, already rely on a private power pole to reach the house at all. If that's your situation, extending supply to a granny flat may involve that same pole rather than a new one. Distributors generally won't put up a brand new street pole to solve a connection problem unless there's genuinely no practical alternative, so for the vast majority of narrow Inner West blocks, running new underground consumer mains from the existing connection point is the standard, and usually the more affordable, path. If your block already has a private pole question to work through, our own guide to private power poles on Inner West terrace and rear lane blocks covers that ownership and access question in full, and our sister site's Sydney wide private power pole installation guide covers the pole build process itself.

7. How this compares to a standard new granny flat connection

The core process, a new or upgraded consumer mains run, a compliant sub board, a Notification of Service Work and Certificate of Compliance for Electrical Work, and network sign off, is the same everywhere in Sydney. Our main site's step by step guide to a new granny flat connection walks through that full sequence in detail. What changes on a narrow Inner West block is purely the practical planning around access, cable route and capacity, worth reading both if your block is a tight one.

Why it's Level 2 ASP work

Any new connection point, metering change, or alteration to consumer mains connecting to the network requires an accredited Level 2 ASP, not a standard licensed electrician working alone. The ASP liaises directly with the network on the connection point and any planned outage, lodges the compliance paperwork, and signs off the finished installation. A standard electrician can wire the granny flat's internal circuits, but the network connection side is Level 2 territory.

How High Demand Electrical helps

High Demand Electrical is a licensed local team, not a call centre, and we work across Sydney's Inner West on exactly this kind of granny flat and secondary dwelling connection, including the tighter, older blocks that need a genuine site assessment rather than a generic quote. If you're after the best electrician near you in the Inner West for a granny flat build, we'll walk your specific block, work out the practical cable route and switchboard position, and handle the network paperwork end to end.

Granny Flat Electrical Connection FAQs (Inner West)

Do I need council approval before the electrical work starts?

Council or complying development approval for the granny flat build itself is separate from the electrical connection, but your electrician will need the approved plans to confirm layout and load before starting.

How long does the electrical side typically take?

Once the network connection is approved, the on-site work is often completed in a day or two, though network approval timing itself varies and isn't something an electrician controls directly.

Can I use the granny flat's power while the main house is on a different retailer plan?

With fully separate metering, yes, each meter can be on its own retailer and plan. With shared or sub-metered supply, both properties are on the one account.

What if my terrace's existing switchboard is already old and at capacity?

It's common on older Inner West terraces. See our guide on shared and ageing switchboards in Inner West semis and terraces for what a proper upgrade involves before adding a granny flat's load.

Does a granny flat need three phase power?

Not usually for standard household appliances. It's more relevant if you're planning EV charging, a larger heat pump system, or a home with heavy simultaneous demand. See our main site's single phase to three phase upgrade guide if you're unsure which your block needs.

Planning a granny flat on a narrow Inner West block? Get a consumer mains and connection quote or call 0402 559 777. Every quote is based on a proper look at your block's access and existing supply, not a guess over the phone.