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No Power in Half the House? Common Causes + Emergency Help London

If half the house has no power but the other half works fine, the usual cause is a tripped RCD or MCB at the consumer unit taking out one bank of circuits — or, less often, a fault on one circuit or a problem with your supply. Check the consumer unit first: look for any switch that’s down or sitting in a halfway position, switch it fully off, then firmly back on. If it won’t stay on, or nothing at the board looks tripped, the fault needs proper diagnosis.

Check the consumer unit first — MCB vs RCD

Your consumer unit (fuse box) is usually in the hallway, under the stairs, in a cupboard or near the front door. Everything below happens on the front of the unit — never remove the cover or touch any wiring inside.

  1. Look for a switch that’s down or in the middle. Tripped devices often rest in a deceptive halfway position that looks almost normal at a glance. Check every switch carefully, with a torch if the light there is out.
  2. Small switch down = an MCB. One circuit is off — for example, downstairs sockets or upstairs lights. Switch it fully off, then firmly on.
  3. Larger switch down = an RCD. On most modern boards, one RCD protects a whole bank of circuits — which is exactly why half the house goes off at once. Push it fully down to off, then firmly up.
  4. If it trips straight back off, unplug everything on the dead circuits — including fridge-freezers, washing machines and boiler plugs — and try again. If it now holds, plug things back in one at a time to find the faulty appliance.
  5. If nothing is tripped at all, check whether your neighbours have power and whether your prepayment meter (if you have one) has credit. Half-house losses with nothing tripped can also point to a supply or main-fuse problem — see below.

Stop and call a professional if: a switch won’t stay on with everything unplugged, nothing at the board is tripped but circuits are still dead, you smell burning or hear buzzing anywhere, or the board is an old type with rewirable fuses. Never open the consumer unit, pull fuses, or touch the meter or main cut-out — the main fuse belongs to your network operator and it’s illegal and dangerous to interfere with it.

Lights work but sockets don’t — what that means

Lighting and sockets run on separate circuits, so it’s completely normal for one to fail while the other works — and it usefully narrows the fault. Dead sockets with working lights usually means a tripped or faulty ring-main circuit, most often caused by an appliance. Dead lights with working sockets points at the lighting circuit — commonly a failed lamp that trips the MCB at the moment it blows. Either way, the MCB-and-unplug routine above is the right first step, and a plug-in lamp carried from room to room is a quick, safe way to map exactly which sockets are dead.

Likely causes, ranked

  1. A tripped RCD taking out one bank of circuits. The classic “half the house” pattern on modern split-load boards — one faulty appliance and everything on that RCD’s side goes dark.
  2. A faulty appliance or blown lamp. The trigger behind most of those trips: heating elements, chargers, extension leads and bulbs that trip the circuit as they fail.
  3. A broken ring circuit or loose connection. If some sockets on a circuit work and others don’t with nothing tripped, a connection has failed somewhere along the ring — often at the back of one socket. Loose connections generate heat, so this one shouldn’t be left.
  4. A failed MCB or RCD. Protective devices wear out; an MCB can fail internally so the circuit is dead even though the switch sits happily in the on position.
  5. A supply problem — one phase down or a failing main fuse. Some London properties, especially converted houses and flats, have supplies where a fault at the cut-out or in the street can kill part of the installation. If neighbours have problems too, or nothing at your board explains it, call your electricity network operator on 105 (free, 24/7) as well.

Renting? Whose job is it — tenant or landlord

If you rent, electrical repairs to the fixed installation — the wiring, consumer unit, sockets and switches — are your landlord’s responsibility, and every private rented home in England must have a satisfactory EICR (electrical safety report) renewed at least every five years. Your own appliances are your responsibility. In practice: do the safe checks above first, because a tripped switch caused by your kettle isn’t a landlord issue. If the fault is in the installation, report it to your landlord or agent in writing straight away. For genuine emergencies — no power at all, burning smells, shocks — landlords are expected to act urgently, and many across Haringey, Hackney and the surrounding boroughs call us directly to attend their tenants’ properties same-day.

When to call an emergency electrician

Our 24-hour emergency electrician service covers London around the clock, with fast response across north and east London. If the dead circuits are non-essential and everything is cold and quiet at the board, waiting for a daytime visit is often the sensible, cheaper call — we’ll tell you which situation you’re in when you phone.

What our electrician will do

As a NICEIC Approved Contractor, all repairs are tested and certified to BS 7671, and we’ll flag honestly if what we find suggests the board itself is at end of life — our fuse board replacement cost guide explains what an upgrade involves.

What it costs

Our minimum charge for any visit is £108 including VAT (£90 + VAT), which covers the call-out and fault-finding — and most half-house power losses are diagnosed and fixed within that first visit. Prices are labour-only; if parts or further work are needed, you get a fixed price quoted before any work starts, so you approve the cost up front rather than discovering it on the invoice.

Frequently asked questions

Why is half my house without power but nothing has tripped?

Usually a failed protective device, a broken connection on a circuit, or a supply-side problem such as one phase down. All three need an electrician — and if neighbours are affected too, ring 105 for your network operator as well.

Will my fridge and freezer be okay?

An unopened fridge keeps food safe for around 4 hours and a full freezer for 24–48 hours. Keep the doors shut, and mention frozen food when you call — it’s one of the things that moves a job up our emergency list.

Could this be a power cut rather than my wiring?

Possibly — check whether neighbours or street lights are affected and call 105 to check for outages. But a fault affecting exactly half your house with the other half working normally is far more often inside your own installation.

Which areas do you cover?

We’re based in Tottenham N15 and cover north, east and central London 24/7 — see our London service areas page for the full postcode list.

No power in half the house? Call F & A Electrical

Rated 9.69/10 from 237 Checkatrade reviews, we find and fix partial power losses across London every week. Call 07407 627542 or 07500 721453 now — we’ll run through the quick checks with you on the phone and get an electrician moving if it needs one.

Common electrical faults — more guides

Fuse box keeps tripping · Burning smell from a socket · RCD won’t reset · Lights flickering