Upgrading a Landed Home to Three-Phase Power: What Actually Happens

Homes are drawing more power than ever — induction cooking, several aircon zones, instant water heaters, a pool pump, a home lift, rooftop solar and a battery, and increasingly an EV in the porch. Stack enough of it and a normal single-phase supply simply runs out of headroom. The fix is a three-phase upgrade — one of the bigger electrical jobs a home can take on, and one that involves SP Group as well as your electrician.

(In plain terms, "phases" are the separate live lines that feed your home. A normal house runs on one line — "single-phase". A bigger supply runs on three — "three-phase" — so it can carry far more power at once, a bit like a three-lane road versus a single lane.)

Here is what actually happens, who does what, what SP Group officially charges, and how long to budget for — the honest version, not a sales pitch.

First: do you actually need three-phase?

Start here, because the honest answer is often no. Three-phase isn't about any single appliance — it's about your total load, everything that might run at once. A single-phase home supply tops out at about 23 kVA (kVA is simply the size of your supply — how much power the house can pull at any one moment), which is 230 V at 100 A. You reach for three-phase when the combined demand outgrows that.

The usual culprits, stacked together: several aircon zones, induction cooking, instant water heaters, a swimming-pool pump, a home lift, a workshop — a sizeable rooftop solar system with a battery (larger solar uses a three-phase inverter, which spreads the generation evenly across all three lines in a way single-phase can't) — and, yes, a fast 22 kW EV charger. Any one of these alone is usually fine on single-phase; it's the pile-up, now and in the years ahead, that tips a home over.

And household loads only travel one way — up. As homes electrify — induction replacing gas, heat-pump water heaters, solar and batteries, one or two EVs — the sensible time to go three-phase is during a renovation, while the board and walls are already open, rather than scrambling for it later.

One myth worth killing early, though: a normal 7.4 kW EV charger runs perfectly well on the single-phase supply you already have. It's only the fast 22 kW charger that needs three-phase — so if EV charging is your only reason, you may not need an upgrade at all. Check before you spend. Still weighing it up? Our Do you need three-phase power? guide is the decision piece; this one is about how the upgrade actually happens.

What a three-phase upgrade actually changes

A supply upgrade isn't one job — it's a coordinated set, and the split between what SP Group owns and what your side owns matters, because it decides who does what and who pays for what.

• ›The meter compartment — SP requires the meters at your front gate pillar or perimeter wall, in a weatherproof box that can be read without anyone entering your property. A three-phase upgrade commonly means rebuilding this to SP's spec.
• ›The main switch and distribution board (the "DB" — the grey unit of switches that feeds the house) — replaced with three-phase gear, and the circuits shared out evenly across the three lines so no single line is overloaded. Modern boards are "split-load": the house is divided into a few protected groups, each with its own safety trip, so if one circuit faults, only that group cuts out — not the whole house. Larger homes often add sub-boards for the attic, outdoor and pool circuits.
• ›Earthing — checked and, on older houses, often upgraded. A proper earth is the invisible bit that makes all the other protection actually work.

SP Group's side

• › The incoming service cable to your house
• › The meter (SP owns and maintains it)
• › Digging and reinstating the public road/verge

Your side (via your contractor)

• › The weatherproof meter compartment at the gate
• › The new three-phase main switch and DB (electrical box)
• › Load balanced across the three phases, earthing
• › The UPVC lead-in pipes to the boundary

SP brings power to your gate; your licensed contractor builds everything from the gate inward — and only SP may remove your old single-phase connection once the new supply is live.

The process: your electrician and SP Group, step by step

The single most important thing to know: your electrician applies to SP Group, not you. Any new connection, upgrade or rewiring must be carried out or supervised by an EMA-Licensed Electrical Worker (LEW) — a government-licensed electrician legally allowed to sign off this kind of work; you can verify any LEW's licence on EMA's ELISE portal. The LEW acts as your agent: you sign a letter of consent and hand over a site plan, and they do the rest. So step one is simply engaging the electrician — everything else follows.

• ›Your LEW works out the load, then files the supply application through SP Group's online eBusiness Portal with your letter of consent and site plan.
• ›SP generally replies within about 10 business days with a quotation stating the connection charge (the fixed fee, covered below).
• ›You pay and sign; SP then assigns a project officer and sends an introduction letter. (SP takes card up to S$40,000, or NETS.)
• ›SP gets the permits to dig in public areas from LTA / PUB / NParks — this alone typically takes about three weeks — then lays the incoming cable, roughly another three weeks.
• ›Once the cable reaches your gate and your side is built, the LEW books the turn-on and submits the paperwork that certifies the work is safe and up to code — Form CS/5 and the Certificate of Compliance (COC). You don't touch any of this; the LEW handles it.
• ›SP inspects; on a pass, a Statement of Turn-On is signed on the spot and the supply is switched on. The first inspection is free.

What it costs

Two parts make up the bill, and only one has a fixed published price. First, SP Group's standard connection charge — a flat fee for a given supply size that, helpfully, is the same no matter how far your house sits from the mains (SP averages it across landed owners). These are SP's official rates for a standard shared-network underground connection:

• ›Watch the small print: a missed or rebooked turn-on appointment costs S$45 (+GST), and meter testing is S$30 (+GST) per meter — separate from the connection charge.

How long it takes

Budget in months, not weeks. On SP's own figures, the SP side is about six weeks after you pay — roughly three weeks for the dig permits, then about three weeks to lay the cable — and switch-on normally happens within four to six weeks of your premises being ready. Add your contractor's board and meter-compartment work on top, and a realistic end-to-end allowance for a landed three-phase upgrade is around two to three months from the first site visit. If you're doing it as part of a renovation, start it early: the supply application is usually the longest single wait in the whole job.

Upgrade the supply, or rewire while you're in there?

A three-phase upgrade does not automatically mean a full rewire — that's a condition call your electrician makes, not a default. The triggers for rewiring alongside the upgrade are real, though: ageing or brittle cable insulation, wiring in the old pre-2009 colours, circuits that trip often, or points that run warm or discoloured.

On the colours: Singapore changed its wiring colour code on 1 March 2009 (old red/black singles and red/yellow/blue phases became brown/blue and brown/black/grey), with both allowed during a transition to 1 March 2011 — a change made by EMA. Older wiring doesn't have to be ripped out just for that, but a mixed-colour board is a sign the installation predates a lot of modern practice and is worth a proper look.

One more thing older landed houses often show: weak earthing (electricians measure it as "high earth-loop impedance"). In plain terms, the earth path may not clear a fault fast enough for a big new load — so the earthing sometimes has to be upgraded before a heavy three-phase load or an EV charger goes in. It's checked against the SS 638 wiring code, and it's the kind of thing a site visit catches before it becomes a problem.

One common case: charging an EV

EV charging is one of the most common reasons homeowners look at three-phase, so it's worth a quick note on the charger's own rules (separate from the supply work). Since 1 April 2026, fixed EV chargers are installed to Singapore's EV charging standard, SS 722 (elevated from the old TR 25 to a full Singapore Standard) — meaning a dedicated circuit, the right safety protection, a properly-rated isolator switch and a type-approved charger, all installed by an LEW. Every charger must also be registered before use on your LTA OneMotoring account.

And to repeat the money-saving point: only the fast 22 kW charger needs three-phase. A 7.4 kW charger runs on the single-phase supply you already have — so confirm which charger you actually want before committing to a supply upgrade for it.

How BSH does it

Three-phase supply, switchboards and heavy-load design aren't a sideline for us — they're core work. For over 30 years, BSH has designed and installed three-phase distribution boards and main switchboards for commercial and industrial buildings across Singapore, as well as for landed homes. So when it's your house, you're getting a contractor whose everyday work is exactly this class of heavy electrical — not a residential-only outfit sizing a three-phase board for the first time.

What that means in practice: we check whether your existing supply and board can take the new load before we quote, we run the SP Group application end to end as your agent, and where the board needs replacing we build it properly — split-load protection, balanced across the phases, tested and certified. Two things we hold ourselves to, worth asking any contractor about: we never tap a heavy new load off the meter compartment or the gate-pillar supply (new loads come off the board, wired to SS 638), and our proposals show you exactly where every part will sit before any work starts. BSH is EMA-licensed, led by Grade 8 LEWs (with a partner Grade 9 LEW where a larger approved load calls for it), BCA-registered, and has wired Singapore homes and businesses since 1993.