Why does my water heater trip the power?

Why water heater tripping happens

The switch that went off tells you something about the fault. HDB's guide to electrical accessories and wiring says the consumer unit holds a main switch, an RCCB and miniature circuit breakers (MCBs), with each single pole MCB protecting one circuit. An MCB trips on an overcurrent from an overload or short circuit. If the heater's circuit breaker (MCB) trips rather than the RCCB, that points to an overload or short circuit on that circuit.

The RCCB does a different job. EMA's electrical safety page says it cuts off electricity when it detects a current leakage that may lead to an electric shock, and names ageing or exposed wires, faulty electrical appliances and damaged insulation as causes. Some boards label this switch ELCB. If the water heater trips the ELCB or RCCB, treat it as a possible leakage fault.

Element faults and moisture

For its storage heaters, Ariston's customer service FAQ gives two causes when the circuit breaker cuts out as soon as the heater is switched on: an incorrect electrical power setting, or an earthed resistance (the heating element), which should be tested and replaced if necessary. For instant heaters, Ariston says a heating, ELCB or safety indicator that is blinking or not lit means you should call for service.

Water and electricity are the other concern. EMA warns against using electrical appliances near water or with wet hands, and against touching an open outlet or switch with wet hands. If there is water on or around the heater switch or point, do not touch it; see the last section for what to do.

Wiring, switch and connection issues

Not every trip starts inside the heater. The wiring, the heater switch and the point are part of your electrical installation. HDB says overheated plugs and frequently blown plug fuses come from loose connections, overloaded circuits or broken cables, and burnt marks at a socket from a plug not fully inserted or an overloaded circuit.

EMA requires electrical works at your premises, including any repair, modification or replacement of the installation, to be carried out by an LEW, who also certifies that it is safe before supply is turned on. EMA also says to have cracked or broken power points replaced by an LEW. The heater point and switch are LEW work, not DIY.

Stop using it until it is checked

EMA explains that an RCCB trips on a leakage that may lead to an electric shock, so resetting it again and again is not a fix. Until the heater has been checked:

• Switch the heater off at its own switch, with dry hands.
• If the RCCB or circuit breaker keeps tripping, leave that circuit off.
• Do not use the heater, even if it seems to work after a reset.
• Look for burnt marks or water near the switch or point, without touching them.

If you cannot tell what is causing the trips, you can compare companies listed for power trip repair.

Plumber, electrician or manufacturer

Who you call depends on where the fault is. The wiring, the heater switch, the point and the circuit breakers need 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. Check the worker's licence card before work starts, or search for them on EMA's ELISE portal, as EMA's page on engaging Licensed Electrical Workers explains.

For a fault inside the heater, such as an earthed element, contact the manufacturer's service team or the installer, and the manufacturer first if the heater is under warranty. You can compare companies listed for water heater repair.

Prices depend on the job, so see plumbing costs and ask what each quote includes.

When to stop and call a professional

Some signs mean you should act straight away. Switch off at the main switch if you can do so safely, keep away from the heater and call an LEW if you notice:

• a burning smell from the heater, switch or point
• scorch marks on the switch, point or cable
• water leaking near the switch or point
• tingling when you touch the taps

At night, you can look for 24-hour electricians in the directory. For other signs that a heater needs attention, read water heater warning signs.

Questions