No Electricity in Part of House: Causes and Fixes

You walk into a room and the lights do not come on. Or you notice that the sockets in one part of the house are dead while the rest of the house has power. Losing electricity in part of your house is unsettling, but it is almost always caused by something straightforward and fixable.

Your home's electrical system is divided into separate circuits — typically including separate circuits for upstairs lights, downstairs lights, kitchen sockets, ring final circuits for other sockets, the cooker, the shower, and any other dedicated supplies. Each circuit has its own protective device (MCB, fuse, or RCBO) in the consumer unit. When one circuit loses power, it is usually because the protective device for that circuit has tripped or blown, or there is a fault in the wiring of that specific circuit.

This guide covers every common cause — from the simple (a tripped breaker) to the more involved (shared neutral faults in older properties). It tells you what you can check yourself and when you need a qualified electrician. For electricians, the later sections cover fault finding techniques for partial power loss scenarios.

Before calling an electrician, these checks take less than five minutes and resolve the majority of partial power loss situations:

A tripped MCB is by far the most common reason for losing power in part of your house. The MCB has detected either an overcurrent (too many appliances drawing too much current) or a short circuit (a fault causing a sudden current surge) and has disconnected to protect the circuit.

Remember that an MCB protects a specific circuit. Check the label on the consumer unit to identify which circuit the tripped MCB controls — this tells you which area of the house is affected and helps narrow down the cause.

A loose connection at the consumer unit is more serious than a tripped MCB. If a cable connection to an MCB or busbar becomes loose, the circuit can lose power intermittently or completely. This is also a significant fire risk because loose connections generate heat.

If you notice any of these signs, do not attempt to investigate inside the consumer unit yourself. The busbars inside carry the full supply current and are at mains voltage. Call an electrician to inspect the consumer unit, retorque all connections, and replace any damaged components.

A damaged cable can cause a complete loss of power to part of a circuit or trip the protective device. Cable damage occurs in several ways:

Cable damage inside walls, floors, and ceiling voids is invisible from outside. An electrician uses insulation resistance testing and continuity testing to locate the damaged section, and may need to replace a cable run if the damage is significant.

This is a more complex issue found primarily in older UK properties (pre-1980s). In a shared neutral arrangement, two or more circuits share a common neutral conductor back to the consumer unit. This was a common and acceptable wiring practice at the time, but it creates a specific problem when the shared neutral is interrupted.

If you notice lights getting abnormally bright, switch off the main switch immediately and call an electrician. Overvoltage can damage sensitive electronics and appliances, and is a sign of a neutral fault that needs urgent repair. An electrician will test for shared neutrals, locate the break, and repair or rewire the affected circuits.

Most UK socket circuits are wired as ring final circuits — the cable starts at the consumer unit, loops through every socket on the circuit, and returns to the consumer unit. This means each socket is fed from two directions, and the load is shared between the two legs of the ring.

When the ring breaks (a disconnection at one point in the ring), the circuit effectively becomes a radial circuit supplied from one end. Sockets between the break and the far end of the ring may lose power entirely, or the circuit may continue to work but with the full load concentrated on one leg of the ring — which can cause overheating.

A broken ring is not always obvious because many sockets may continue to work. It is typically discovered during an EICR inspection when the electrician performs a ring continuity test, or when an investigation is triggered by tripping or partial power loss.

If your consumer unit uses fuse carriers instead of MCBs (common in properties built before the 1990s), a blown fuse is the equivalent of a tripped MCB. There are two types:

If you are replacing fuses regularly on the same circuit, the circuit has a recurring fault that needs investigating. Fuse boards also provide no RCD protection, which is a significant safety concern. Consider a consumer unit upgrade to a modern MCB/RCBO board for better protection and convenience.

If resetting the breaker or replacing a fuse restores power and it stays on, you may not need an electrician immediately (but monitor the situation). Here is when you definitely need professional help:

An electrician will perform continuity testing, insulation resistance testing, and load measurements to identify the fault. For recurring issues, a full EICR will identify all defects across the entire installation and prioritise them by severity.

Partial power loss calls require you to quickly narrow down whether the issue is at the consumer unit, in the circuit wiring, or at a specific point:

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