What is PME earthing failure and why is it dangerous?

PME stands for Protective Multiple Earthing. It is the earthing arrangement used in the majority of homes across the UK. Your electricity supplier's network uses a single conductor that acts as both the neutral and the earth return path. Multiple connections to ground along the network keep voltages balanced under normal conditions. This system is reliable when working correctly, but it has one serious vulnerability: if that combined conductor breaks or loses its connection to ground, something called an open PEN conductor fault occurs. When this happens, the earth in your home is no longer connected to true ground. Instead, it becomes energised at a voltage that can be high enough to kill. Because all the metalwork in your home is bonded together under PME, this means your water pipes, gas pipes, radiators, taps, and any earthed appliance casing could all rise to a dangerous voltage simultaneously. You would not necessarily see any warning signs. The lights might still work. The sockets might still function. But touching a tap and a cooker at the same time, or stepping from a bathroom into a garden while touching a pipe, could complete a circuit through your body. Some signs that might indicate a network neutral problem include: Lights flickering or appearing unusually bright or dim across the street as well as in your home. Neighbours reporting similar electrical problems at the same time. Smell of burning or unusual heat near your meter. RCD tripping for no obvious reason. What you should do: Do not touch any metalwork inside or outside the property until the situation is confirmed safe. Do not use water from taps or touch radiators. Turn off your main switch if you can do so without touching metalwork. Call your Distribution Network Operator straight away. Their emergency number is on your electricity bill and is free to call at any time. Do not attempt any investigation yourself. This is a network fault, not a household wiring problem, and requires specialist equipment to diagnose safely.