Aircon · Guide

Aircon Isolator Switch and Power Point Guide

Aircon isolator switch beside a condenser unit

Short answer: a fixed air-conditioner needs an isolator switch, a dedicated, lockable switch near the unit that fully cuts its power for servicing or emergencies. It is sized to the unit (commonly 20A or 32A), and in HDB flats a new 15A power point may need a permit if your flat’s loading was not upgraded for it.

What an isolator is, and why aircon needs one

An isolator switch is a disconnection point built for a fixed appliance. Mounted near the aircon, usually by the outdoor condenser, it lets a technician cut all power to the unit and safely lock it off before working on it, without switching off circuits at the main DB box. An ordinary wall switch is not designed for that duty. This is why every proper aircon installation includes an isolator, and why servicing firms ask for one.

Sizing: 15A, 20A or 32A

The rating is matched to how much current the aircon draws. Small units may sit on a 15A supply; larger and multi-split systems commonly need a 20A or 32A isolator on a dedicated circuit. Getting this right is an electrician’s call, undersizing trips the circuit, oversizing wastes capacity, and it ties directly to whether your flat’s loading can carry the unit at all.

The HDB 15A permit rule

In HDB flats, adding a 15A power point can require a permit when the flat’s electrical loading has not been upgraded to support it, the extra load affects the flat’s overall capacity. A licensed electrician checks your loading first; if an upgrade is needed, that becomes part of the plan. Our HDB electrical loading guide explains how to tell whether your flat is already upgraded.

What it costs

As market guide ranges: a 20A isolator around S$160, a 32A around S$300, and a new 15A power point around S$115, installed, with the final figure driven by cable run and whether a new circuit is required. See the full table on our price guide.

Before your aircon install: a quick checklist

Confirm there is a suitable isolator near the condenser; confirm the circuit and isolator are sized to the unit; and confirm your flat’s loading supports it, sorting any permit before work starts. Getting the power point and isolator right first means the aircon installer just connects and goes.

Aircon isolator and power point questions

Do aircons need an isolation switch?

Yes, an isolator is standard and expected for a fixed air-conditioner. It provides a local, lockable way to cut all power to the unit for servicing or in an emergency, without having to switch off circuits at the main DB box. Installers and servicing technicians rely on it, and a proper aircon installation includes one.

What is an aircon isolator switch?

It is a dedicated switch mounted near the aircon (typically the outdoor condenser) that isolates the unit’s power completely. Unlike an ordinary wall switch, an isolator is designed to safely disconnect a fixed appliance so it can be worked on with no live parts, which is why servicing technicians insist on one.

Why use an isolator instead of a normal switch?

An isolator is rated and built to fully disconnect a fixed load and stay safely off during work, often with a lock-off feature. A normal light switch is not designed for that duty. For a fixed appliance like an aircon or water heater, the isolator is the safe, correct disconnection point.

What size isolator does an aircon need?

It depends on the unit’s current draw, common domestic isolators are 20A or 32A, sized by the electrician to the aircon’s rating. A larger system, or a multi-split serving several rooms, may need the higher rating. The electrician matches the isolator and its circuit to the specific unit.

How much does an isolator switch cost in Singapore?

As a market guide, a 20A isolator is around S$160 and a 32A around S$300, installed. A new 15A power point is around S$115. The final figure depends on cable run and whether a new circuit is needed. Our price guide has the wider ranges; these are benchmarks, not fixed prices.

Do I need an HDB permit for a 15A power point?

You can, if the flat’s electrical loading has not been upgraded to support it. HDB requires a permit for adding 15A power points in flats that were not wired for that load, because it affects the flat’s electrical capacity. A licensed electrician will check your loading and advise before installing.