—Wiring and circuits
Single-phase and three-phase supplies
Most apartments have single-phase supplies. Many villas have three-phase supplies. The difference matters when adding heavy loads.
A single-phase supply provides one live conductor and is common in smaller homes and apartments. A three-phase supply provides three live conductors, allowing more power to be distributed and some equipment to use all three. Larger villas with multiple AC units, pumps and heavy appliances often have three-phase supplies.
Wiring guides explain how circuits are put together and changed, so a quotation or a recommendation is easier to follow.
In a three-phase installation, circuits are spread across the phases to balance the load. Adding new heavy loads — such as EV chargers or large AC units — involves checking which phase they go on and whether the supply has capacity.
01In short
The points that matter most
Single phase
Common in apartments and smaller homes.
Three phase
Common in larger villas.
Balance matters
Loads are spread across phases.
02Detail
Practical implications
Adding loads
Choosing the phase for new circuits.
Equipment
Some equipment requires three-phase supply.
Supply capacity
The total available supply limits additions.
How to tell from the board
Three-phase boards often have a main switch spanning three or four poles and groups of devices marked by phase; an electrician can confirm it.
Imbalance symptoms
Heavy loads concentrated on one phase can make that phase run near its limit while others are lightly loaded.
03Checklist
Find out
Your supply type
From the board or meter.
Major loads
AC, pumps, heaters, chargers.
Future plans
EV charging or extensions.
04Questions
Questions people ask
- Do I need three phase for an EV charger?
- Not necessarily; many chargers run on single phase. Capacity is the key.
- Can single phase be upgraded?
- Supply changes involve the supply authority and are assessed case by case.
- Why do some lights dim when AC starts?
- Load on one phase can affect circuits on it; balance helps.
- Is three phase more dangerous?
- It carries higher voltage between phases, which is one reason board work is for qualified people only.
05Related
Related guides
- Wiring for an extension, annex or garden roomMore on the circuits behind the same problem.
- Signs that wiring may need replacingMore on the circuits behind the same problem.
- MCB or RCBOA related choice for the same kind of work.
- Surface or concealed wiringA related choice for the same kind of work.
This guide sits under electrical wiring. All topics are on the guides page.
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