Why did I get a shock from an appliance?

Electric shock from appliance: what it means

A tingle or a sharper jolt means some current has left its circuit and found a path through something you touched, such as the metal case of an appliance or a tap.

The Energy Market Authority (EMA) says a residual current circuit breaker (RCCB) or earth leakage circuit breaker (ELCB) cuts off electricity when it detects a current leakage that may lead to an electric shock. EMA lists the causes of leakage as ageing or exposed wires, faulty electrical appliances and damaged insulation.

In an HDB flat, the RCCB sits in the consumer unit (CU) with the main switch and the miniature circuit breakers (MCBs). HDB says the RCCB cuts off electricity in the flat when it detects an earth current leakage, while an MCB trips to cut supply to its own circuit on an overload or short circuit. HDB also advises replacing wiring when its lifespan is over or it has deteriorated, and says a Licensed Electrical Worker (LEW) can check the wiring and advise whether it needs replacing.

Earthing faults

Many appliances have a metal case, and taps, pipes and metal sinks are metal too. If insulation in an appliance or its cord is damaged, a small leakage current can reach that metal, and you can feel it as a tingle when you touch it. This is an earth leakage shock.

Do not take comfort from an RCCB that did not trip. A breaker that stayed on does not prove that the appliance, the earthing or the breaker itself is working properly, so have it tested.

EMA says all residential premises must have an RCCB or ELCB with a rated residual operating current not exceeding 30mA, and to test it once a month. It is usually in the distribution board (DB box), as a switch with a "Test" button.

If your breaker keeps switching off by itself, see our guide on what to do when your ELCB keeps tripping.

Stop using and isolate

The Consumer Product Safety Office (CPSO) says to switch an appliance off before unplugging it, to hold the plug, not the cord, and to keep liquids away from appliances and sockets.

1. Stop and keep others away. Do not touch the appliance or tap again, and keep other people away from it.
2. Switch off only if dry. If your hands and the floor are dry and the socket is away from water, switch off at the socket, then unplug by holding the plug, not the cord.
3. Do not use it again. Leave it unplugged and out of use, even if it seems to work, until it has been tested.
4. Leave wet areas alone. If you felt the shock from a tap or in a wet area, do not touch the switches there. Keep away and call a Licensed Electrician.

If you notice tingling from tap fittings, a metal sink or a water heater, do not touch nearby switches, sockets or the DB box, and do not try to trace the cause yourself.

Testing by an LEW

EMA says electrical work in an HDB flat needs a Licensed Electrician, the class of LEW approved for loads of up to 45kVA. EMA's guide to engaging Licensed Electrical Workers lists repair or replacement of consumer control units or circuit breakers among the work an LEW should carry out or supervise.

EMA's electrical safety guidance says any repair or replacement to the electrical installation must be carried out by an LEW, who also inspects and certifies that it is safe before supply is turned on.

Tell the electrician which appliance or tap gave the shock and whether the RCCB tripped, and ask them to test the appliance circuit, the earthing and the RCCB. You can compare licensed electricians in the directory.

FROM THE HOMEZYPRO DIRECTORY

Published call-out rates

For the most common unit (per visit), the lowest published call-out rates from 4 companies run from S$40 to S$300 per visit, per visit, before any repair. Each figure is one company's own advertised rate with its conditions, not a quote.

See 4 published call-out rates and sources

Lowest matching advertised rate per company, in SGD as published. "From" marks a starting price and ranges are shown in full. Check the source for minimums, GST and inclusions.

Company	Service as listed	Rate	Source
Fix My Heater	Transport & inspection fee (waived when repair proceeds)	S$40 per visit	fixmyheater.sg
Sin & Goh Electrical Engineering	Basic attendance / call-out fee	S$40 to S$80 per visit	wireman.com.sg
Yeobuild HomeRepair	Call-Out Charges	S$70.85 per visit	yeobuild.com.sg
Mirza M&E Engineering Pte.Ltd.	Call-out	S$300 per visit	mirzaengineering.com.sg

4 companies publish a call-out rate, all per visit and before any repair. Their lowest published rates run from S$40 to S$300 per visit, and the two middle rates are S$40 and S$70.85 including GST per visit. As printed, one company's basic attendance fee runs from S$40 to S$80 per visit, and another says its S$40 per visit transport and inspection fee is waived when the repair proceeds. See our electrician call-out fee guide for what to ask.

When to stop and call a professional

Call a Licensed Electrician if you notice any of these:

• any shock from an appliance, socket or switch, even a mild one
• a tingle from a tap, a metal sink or a water heater
• the RCCB does not switch off when you press its test button
• scorch or burn marks on a plug, socket or cord

Outside office hours, look for 24-hour electricians. Otherwise, compare electrical companies in the directory.

Questions