Can a faulty neutral wire in my consumer unit cause intermittent RCD tripping?

Your RCD is designed to protect you from electric shock and fire by constantly comparing the current flowing out on the live wire with the current returning on the neutral wire. Under normal conditions these two values match almost perfectly. When they do not match, the RCD concludes that current is leaking somewhere it should not be, and it trips to cut the power. A faulty neutral wire can upset this balance in several ways. A loose connection on the neutral bar inside the consumer unit is the single most common cause. Over time, thermal cycling causes terminals to work loose, and a poor connection creates resistance in the neutral path. This resistance causes the returning neutral current to fluctuate, and the RCD sees that fluctuation as an imbalance. Corrosion on neutral terminals is another frequent culprit, particularly in older consumer units or in properties where damp has been a problem. Corroded connections are unreliable and can cause exactly the kind of intermittent behaviour you are experiencing, where the RCD trips on some occasions but not others. A shared or overlapping neutral, where the neutral from one circuit is accidentally connected to the neutral bar position belonging to another circuit or to a different RCD zone, can also produce confusing intermittent faults. What you can safely do yourself: 1. Note exactly which circuits lose power when the RCD trips, as this helps the electrician narrow down the fault. 2. Note when tripping happens, for example during heavy rain, in the morning when appliances start up, or seemingly at random. 3. Check whether unplugging certain appliances prevents the trip. 4. Look at the consumer unit from a safe distance for obvious signs of burning smell or discolouration around the casing. What you must not do is open the consumer unit cover or touch any terminals inside. Even with the main switch turned off, the terminals connected to the incoming supply cable from the meter remain live and can deliver a fatal electric shock. Call a qualified electrician registered with a competent person scheme such as NICEIC, NAPIT, or SELECT. They can safely open the unit, inspect the neutral bar, re-torque all terminals, and carry out the tests needed to confirm the fault. This is not an expensive job if caught early, but ignoring it risks nuisance tripping, equipment damage, and in the worst case a fire caused by arcing at a loose connection.