Your Boiler Trips Your RCD Or Circuit Breaker

Have you checked the fusebox and discovered that it's the water heater that's causing the power to trip in your house? This troubleshooting guide will show you which things you need to look at to find the source of this malfunction.

THE POTENTIAL CAUSES FOR THIS FAULT:

• The electric wall socket is faulty

• One or more heating elements are faulty

• Water is leaking somewhere

• Wires or connectors have melted

WARNING
Before you do anything to your appliance, make sure you disconnect it from the power supply.
There is a risk of electric shock.

The electric wall socket is faulty

One of the first things to check is the condition of the electric socket dedicated to your hot water tank: is it broken or melted? If it is, you'll probably need to replace the socket and, if necessary, the water heater cable.

One or more heating elements are faulty

Unscrew the safety cover on your hot water tank (it's normally located underneath) using a cross-head screwdriver. This will expose the heating elements for you to see. These come in two kinds: the immersed type (which therefore sits inside the tank) and the type covered with a sheath (which therefore does not come into contact with the water).

• Immersion type elements (which come into direct contact with the water) are more likely to develop faults due to the fact that limescale builds up on them. This ends up damaging the element's insulation, causing the water to come into contact with the element's internal filament and trip the fusebox.
• The other type of element is fitted inside a sheath (which resembles a spinal column) and held in place by a central screw. It therefore does not come into contact with the water. When this kind of element comes on, it heats the sheath via the process of radiation, and the sheath, in turn, heats the water. Due to the expansion and contraction involved, the screw that holds the element in place can corrode and break, resulting in it no longer maintaining the element firmly in position. This will cause it to lean (like the Tower of Pisa) and come into contact with the metallic sheath. This contact will then cause the fusebox to trip. To find out if there is a fault with this kind of element, you can try disconnecting it then switching the power back on. If the power no longer trips, it's highly likely that it's a fault with this kind of element.

You can also use a multimeter in mega-ohm mode to check the condition of the elements (and determine whether any are faulty). After first turning off the electricity to your water heater, disconnect all the element's connectors and place one of the multimeter's probes on one of the element's terminals and the other on a grounded metal part of the hot water cylinder or something else metal and grounded in the room. If a value is displayed, this means the element has a leak (to ground). If this is the case, the element will need to be replaced.

Buy a water heater heating element

Water is leaking somewhere

If the elements on your water heater are in good working order, you will need to check whether water is leaking anywhere: any water escaping could be reaching electrical components on the cylinder, such as the thermostat or the element, and this will cause the power to trip. Check the watertight seal to ensure it isn't leaking. If it is, replace it. It could also be a hole in the tank that's causing a leak. If this is the case, you will unfortunately have to replace your entire hot water cylinder.

Buy a water heater spare part

Wires or connectors have melted

Check the condition of the various connectors behind the safety cover on your hot water cylinder: are there traces of burning on the thermostat terminals or any other components? Have the wires melted anywhere? If any of these things has happened, you will need to replace the affected part and/or redo the wiring to prevent the problem occurring again.