This whole fridge affair is getting more confusing to me. How is the RCD catching spikes? Surely this would be a taylormade job for a surge arrestor or MOV device. How is the fridge generating spikes other than the simple switching on and off of a standard induction motor?
I still don't understand why it's accepted practice to hard wire the fridge on a spur circuit with an isolator rather so you can omit earth leakage protection rather than having the low ins fault localised and repaired.
Of course protecting a circuit with an RCD is more desirable because of the added protection but if nuisance RCD tripping can't be avoided because of the way the appliance operates then another solution must be found.
Since I started this thread iv'e done a little research into the problem and had a look in BS7671.
The clients fridge freezer is quite large and has all the extras and i'm assuming either the defrost function or the ice maker function is causing the problem and also there are alot of other electrical items plugged into this ring circuit and as
reg 314.1 states in BS7671, this should be avoided to reduce the possibility of unwanted tripping due to excessive protective conductor currents.
I came across a site that gave me some useful information you might find interesting Marv...
Possible Causes Of RCD Tripping
Faulty appliance – unplug all electrical appliances, does the RCD reset OK? If the RCD resets OK plug the appliances back in one at a time. Reset the RCD as you plug each appliance back in to find the faulty appliance.
Incorrect RCD current rating – RCDs have ‘current ratings’ similar to fuses. The current rating is the current that trips an RCD. The current rating of the RCD could be too low. Seek advice from a qualified electrician.
Poor quality RCD – poor quality RCDs can trip when they shouldn’t. Seek advice from a qualified electrician.
Items with motors or pumps starting – many items with motors or pumps, for instance showers and pond pumps, cause
momentary electrical spikes that are big enough to trip RCDs. Seek advice from a qualified electrician.
Older washing machines – aging washing machine heating elements can cause
momentary electrical spikes that are big enough to trip RCDs.
Certain wash cycle phases – some cycles of the washing machine, for instance the spin cycle, can cause
momentary electrical spikes that are big enough to trip RCDs.
Certain dishwasher cycles – some parts of the dishwasher cycle draw a lot of current, a faulty component, for instance the motor, can trip an RCD.
Overloading a washing machine – too many items in a washing machine can cause certain wash cycles, for instance the spin cycle, to trip an RCD.
Fridges and freezers cooling – the fridge or freezer cooling motor starting.
Turning a sun bed on – a sun bed uses a lot of electrical power, the surge in electrical power can trip an RCD.
Turning an heating element on after a long time of being off – moisture in heating elements can trip an RCD, for instance in a sun bed or electric fire. Try resetting the RCD a few times so that the heating element can cause the moisture to evaporate.
Pond pump faulty – pond pumps sometimes have to ‘work very hard’– for instance when they have ‘digested’ part of a plant from the pond. Check your pond pump for blockages.
Moisture in outside electrical distribution boxes – remove the supply and dry the distribution box. Check the weather seals have not perished.
Moisture in outside electrical sockets – remove the supply and dry the electrical socket. Check the weather seals have not perished.
Ice maker on a fridge – a faulty ice maker on a fridge can cause ‘nuisance’ RCD tripping.
De-frost timer on a fridge or freezer – a faulty defrost element on a fridge or freezer can cause ‘nuisance’ RCD tripping.
Central heating elements – faulty heating elements can cause an RCD to trip when they are turned on by a timer.
Water heating elements – faulty water heating elements can cause nuisance RCD trips when the thermostat tells them to heat the water.
Moisture in wiring – moisture in the electrical wiring is a common cause of RCD trips. Have you just emptied a bath? Taken a shower? Is it raining – rain can get into the electrical wiring under the floors or in the loft.
