Question: Why does my breaker trip when the water heater and oven run together?
Answer: Because they are almost certainly sharing a circuit that was never designed for both. An instant water heater draws well over 3 kW on its own; an oven or built-in hob pulls a similar load. Two such appliances on one general circuit overload the cable and breaker — the breaker trips by design, but the cable running hot behind your walls is the real risk. The fix is not a bigger breaker; it is giving each high-load appliance its own dedicated point: a separate cable run from the distribution board, with cable sized to the load, its own protective device, and an isolator within reach of the appliance.
This article covers the aircond, water heater & oven point sub-service under electrical services, starting from RM 220 per point. Related scopes: new power point & switch installation for general sockets, lighting points, and DB box upgrade & rewiring when your board has no capacity left. If your RCCB already trips, see RCCB keeps tripping and power tripping frequently. For older wiring overall, read safe electrical wiring upgrades for old houses.
Which Appliances Need a Dedicated Point
| Appliance | Why it needs its own circuit |
|---|---|
| Instant water heater | Highest constant draw in most homes; works adjacent to water daily |
| Storage water heater | Sustained heating load; older tanks often share circuits from decades ago |
| Air conditioner | Compressor start current plus continuous run load per unit |
| Built-in oven / induction hob | 2–3 kW sustained during cooking |
| Anything hard-wired | Fixed appliances belong on hard-wired dedicated points, not plug sockets |
The published scope covers heavy-load 20A–32A dedicated points with the correct isolator and cable sizing per appliance — the cable, breaker and isolator are matched to each other and to the load, never mixed.
What a Dedicated Point Installation Includes
- Load calculation — the appliance's rated load determines cable size and breaker rating; the existing DB capacity is checked to confirm it can take another circuit.
- Cable run — a new cable is pulled from the distribution board to the appliance location, concealed where the building allows.
- Protection device — a dedicated MCB of the correct rating goes into the DB for that circuit, under the house's RCCB protection.
- Isolator — a switch installed near the appliance (above the door or beside the unit) so it can be safely cut off for servicing without touching the board.
- Termination — hard-wired connection or a dedicated outlet at the appliance end, per the appliance type.
- Testing — circuit tested, breaker behaviour verified, and the run labelled at the DB.
Electrical work is carried out by wiremen registered with Suruhanjaya Tenaga (ST), as published for the company's electrical service, with a 12-Month Electrical Workmanship Warranty.
Signs Your Home Is Missing Dedicated Points
- The breaker trips when two heat-producing appliances run at once.
- A water heater or aircond was "plugged in" by extending a general socket with an adapter.
- Extension cords or multi-plugs run permanently for a fixed appliance — why this is dangerous is covered in the old-house wiring guide.
- The DB has no spare ways left, or old circuits have unclear labelling.
- New appliances trip the RCCB — see RCCB tripping for how to read that symptom.
Water Heater Points: Extra Care
A water heater is the one high-power appliance that also lives next to water every day, so its point gets extra attention:
- Working RCCB protection on the circuit, verified by test — the ~30 mA household RCCB is the last line of defence against electrocution.
- Correct earthing, actually verified at the point, not assumed.
- Isolator within reach so the heater can be isolated for descaling or element replacement.
- Cable diameter matched to the heater rating — undersized cable is the classic cause of warm socket plates behind showers.
Cost Factors
The published rate starts at RM 220 per point; electrical services start at RM 280 overall. Final cost depends on:
- Cable run length and concealment difficulty.
- Appliance load rating — the heavier the load, the heavier (and costlier) the cable.
- Whether the DB has spare ways, or needs a DB upgrade first.
- Isolator type and termination (hard-wired vs dedicated outlet).
- Patching where cable channels are opened.
The electrical installation cost estimator gives a ballpark before a site check.
Frequently Asked Questions
Can a 13A socket run my instant water heater?
Most instant water heaters sold in Malaysia draw more than a 13A circuit should supply continuously, and warm-up plus variable draw makes shared socket circuits unreliable. Manufacturers specify a dedicated supply for a reason — follow the appliance's stated rating.
My house is old — do I need rewiring or just new points?
It depends on the wiring condition. If the cables and DB are in good shape with spare capacity, adding dedicated points is enough. If the wiring is decades old with rubber or brittle insulation, see safe electrical wiring upgrades for old houses — rewiring may be the safer answer. A DB inspection settles the question.
Does a new point include a new breaker at the DB?
Yes — each dedicated circuit gets its own protective device in the board, sized to the appliance and cable. Nothing is tapped off an existing circuit's breaker.
Give Heavy Appliances Their Own Circuit
One appliance, one circuit, one breaker — that is the rule that stops nuisance trips and silent overheating. KL Servis Rumah installs dedicated appliance points across Kuala Lumpur and Selangor.
Send photos of your DB, the appliance location and its rating label — WhatsApp the electrical team.