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POWER LOSS & SUPPLY FAULT GUIDE

Half the House Has No Power

When roughly half the property loses power, one side of a split-load consumer unit, one RCD group, several RCBOs or a shared supply connection may have failed.

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Stop if there is heat, burning, arcing, exposed parts or damaged supply equipment

Do not remove consumer-unit covers, open electricity meters, disturb sealed cut-outs or touch exposed conductors. Leave affected equipment off and contact a registered electrician, supplier or network operator as appropriate.

MOST LIKELY CAUSES

Start with these

One RCD group tripped Split-load boards often divide the property into two groups.
Several circuits share one fault One appliance or circuit may trip a device serving multiple areas.
Loose supply connection A failed link or neutral can affect a section of the board.
Multiple RCBO or supply issue Less common, but several circuits can be lost together.
◫ Symptom variations Match the exact pattern before testing. ⌄
  • Some sockets and lights work while others do not
  • One side of the consumer unit appears off
  • Upstairs works but downstairs does not
  • Power returns after resetting one RCD
  • The same half trips repeatedly
✓ Quick checks Safe checks using front-panel controls and visible information only. ⌄
  1. Check whether the whole property or only certain rooms are affected.
  2. Look for a wider local outage.
  3. Inspect the consumer unit for a tripped breaker, RCBO, RCD or main device.
  4. Check the electricity meter display and prepayment status where applicable.
  5. Attempt one controlled reset only if there are no danger signs.
If power returns: reconnect or restore loads gradually and monitor the supply.
If the fault remains: leave affected circuits off and arrange the correct professional response.
1 Fix 1 — Identify the dead areas Follow this check without opening live or sealed electrical equipment. ⌄

Process

List which rooms, lights and sockets are affected.

Success looks like: The pattern matches one consumer-unit group.
Failure means: An irregular pattern may indicate a wiring or supply issue.
2 Fix 2 — Check the RCD group Follow this check without opening live or sealed electrical equipment. ⌄

Process

Move the affected RCD fully to OFF, then reset once.

Success looks like: The group remains on.
Failure means: If it trips again, isolate connected circuits and appliances.
3 Fix 3 — Unplug appliances on the dead side Follow this check without opening live or sealed electrical equipment. ⌄

Process

Remove portable loads before another controlled reset.

Success looks like: The RCD stays on after one appliance is removed.
Failure means: If not, fixed wiring or equipment needs testing.
⌁ Common causes explained Why the power or supply may fail. ⌄

When roughly half the property loses power, one side of a split-load consumer unit, one RCD group, several RCBOs or a shared supply connection may have failed.

Power loss can originate inside the property, at the meter, or on the electricity network. Identifying which protective device operated and how much of the property is affected is the quickest way to narrow it down.

⌘ Advanced diagnostics Technician-level testing for a competent electrician. ⌄
  • Map circuits to the affected RCD or RCBO group.
  • Test leakage current and insulation resistance.
  • Check neutral bars and shared neutrals.
  • Inspect busbar and supply links for heat damage.
  • Test permanently connected loads individually.
▣ Parts that may need replacing Components commonly linked to this fault. ⌄
  • RCD or RCBO after testing
  • Neutral-bar connection
  • Busbar or supply link
  • Faulty appliance
  • Damaged circuit cable
! When to call an electrician or supply provider Conditions that should end DIY troubleshooting. ⌄
  • The fault remains after one controlled reset.
  • There is burning, heat, buzzing, crackling or visible damage.
  • The main switch, RCD or breaker will not stay on.
  • The meter or sealed supply equipment appears damaged.
  • Lights become unusually bright or voltage appears unstable.
  • Only your property is affected and no internal protective device has operated.
? Frequently asked questions Common questions about supply faults. ⌄

Who should I call for a complete power outage?

Check whether neighbours are affected. A wider outage belongs to the electricity network operator; a fault limited to your installation may need an electrician.

Can a faulty appliance cut power to several rooms?

Yes. One appliance can trip an RCD that protects several circuits.

Should I repeatedly reset the main switch or RCD?

No. One controlled reset is enough to establish whether the fault remains.