Single phase vs three phase basics
What is the difference between the two supplies?
Voltage and capacity. The SP Group handbook on applying for an electricity connection describes low tension supply as 230V single-phase or 400V three-phase. Single-phase covers the needs of most flats and many houses. Three-phase is the route SP gives for loads larger than a single-phase supply can carry.
How much can a single-phase supply carry?
Up to 23kVA, 100A. SP lists that ceiling for 230V single-phase supply in its connection handbook, with larger loads supplied at 400V three-phase. For a household, the number becomes relevant when you add up everything that may run at once: aircon compressors, an oven, a heater and a charger.
How can I tell which supply my home has?
Ask a Licensed Electrical Worker (LEW), or start with the labels on the outside of your distribution board (DB box). Our guide on how to read your DB box explains what the markings and switches mean. Look only: do not open the cover or touch any wiring.
Who needs three-phase power
Which homes usually look at an upgrade?
Landed homes with heavy combined loads. Questions about a three phase landed house setup tend to surface during a rebuild, when more bedrooms each get their own aircon and a porch charger or pool pump joins the list. What matters is the total load at peak moments, not any single appliance.
How do I know if my load is close to the limit?
Your LEW is the person to work that out. Before the visit, list every large appliance you own or plan to add, with the power figure from its nameplate or manual, and note which ones run together on a hot evening. That list helps the LEW judge whether single-phase still fits.
Why is this mostly a landed-home topic?
Because HDB flats take their supply through the block. Flat owners cannot apply to SP for three-phase themselves, and load upgrades for flats are an HDB programme matter. Our article on HDB electrical load upgrading covers that route, so a flat owner in Tampines or Toa Payoh should start there.
How a 3 phase power upgrade in Singapore is applied for
The Energy Market Authority (EMA) says home electrical work, including installing, repairing or modifying wiring, should be carried out or supervised by a Licensed Electrical Worker. EMA says electrical work in an HDB flat needs a Licensed Electrician, the class of LEW approved for loads of up to 45kVA. Our guide to what work needs an LEW covers more.
What does the LEW send to SP?
An application on the SP eBusiness Portal, with a letter of consent. The SP handbook says customers must apply through their LEW. Ask your LEW early what the letter needs and who signs it, so it is ready on time.
Can I check feasibility while plans are still changing?
Yes. SP's handbook says that when an upgrade is still at the planning stage, the LEW may first submit a consultation. That suits owners mid-way through designing a rebuild who want a clearer picture before the electrical layout is fixed. Raise it early.
How long does it take, and what happens to old connections?
It varies. SP's handbook says lead time depends on network availability and any reinforcement needed. Each premises is limited to one intake connection point, so when an existing home's load is upgraded, all existing service connections must be amalgamated into one intake. Flag any second supply point.
Meters, the gate pillar and the DB box
Where does the meter compartment go?
At the gate pillar or perimeter wall. SP's handbook says meters and service cables for landed properties sit in a weatherproof compartment there, never inside the house. If your gate or front wall is being rebuilt at the same time, tell the builder and the LEW so the compartment is planned in.
Will my DB box need changing?
It may. Moving from single-phase to three-phase changes the supply reaching the board, and the DB box inside the house may need replacing to suit. Your LEW will say whether yours can stay. Our DB box replacement page lists companies offering the job; quotes depend on the job.
NEXT STEP
See electrical companies in the directory with their published prices, the areas they say they cover and their sources.
Compare electriciansCar chargers, solar and big appliances
What should I sort out before adding a charger?
The rest of your load list. An electric vehicle (EV) charger is one more large load that can overlap with evening aircon use, so your LEW should weigh it with everything else in the house. For the charger itself, read our guide to an EV charger for a landed home.
Where does solar fit in?
In the same planning conversation as the supply upgrade. If solar panels are on your list, read our guide to solar panels for landed homes before the LEW settles the load plan. Raising both at once means the meter area, the DB box and any new cabling can be discussed together.
Where to go next
Three-phase is usually one item in a larger landed project. Our landed homes FAQ gathers the other questions that come with a house. For the supply, the order is short: list your heavy loads, speak to a Licensed Electrical Worker, consider a consultation with SP while plans are still moving, then settle the meter position and DB box before finishes go in.
Questions
Can an HDB flat get three-phase power?
No, not through an application of your own. HDB flats take their supply through the block, so owners cannot apply to SP for three-phase themselves. Load improvements for flats are an HDB programme matter, covered in the HDB load upgrading article linked above.
Do I need three-phase power for a home EV charger?
Not necessarily. Whether a charger tips the balance depends on what else your home draws at the same time. Your Licensed Electrical Worker can assess the full load, and the EV charger guide above covers the charger itself.
Will three-phase power lower my electricity bill?
No. Three-phase changes how power is delivered to your home, not the tariff you pay. Your bill follows how much electricity you use, so the lever is usage: fewer hours of aircon in empty rooms and switching off what is not needed.
Do I need a new account with SP after the upgrade?
No, as long as the supply stays at low voltage. SP's handbook says an account holder does not need to open a new account in that case, and it lists 400V three-phase as low tension supply. Ask your LEW if your plans go beyond that.
Can my electrician apply for the upgrade for me?
Yes, if they are a Licensed Electrical Worker. SP's handbook says customers must apply through their LEW, who submits on the SP eBusiness Portal with a letter of consent. EMA's page on engaging licensed workers explains how licensed workers are classed, so check the licence before work starts.
Does the meter move during a three-phase upgrade?
Your LEW will tell you, since it depends on where the meter sits now. SP's handbook says landed properties keep meters and service cables in a weatherproof compartment at the gate pillar or perimeter wall, never inside the house. Ask whether yours needs rework.
Practical guidance for planning a home job in Singapore. Company prices come from the HomezyPro directory, each linked to its source; rules and safety points link to the agency or manufacturer that sets them. This is not a site inspection, a quote or professional advice for your home.
How HomezyPro worksYOUR NEXT STEP
Find the right team for your home.
Compare services, published prices and sourced reviews. Contact the company directly to confirm your job and availability.
Explore electrician companies