Residential
Residential blocks
Many homes on one incoming supply, so one fault reaches all of them.
In short
What is broken neutral and PEN fault protection?
Broken neutral and PEN fault protection detects a break in the network conductor that carries both neutral and earth on a PME supply, then raises the alarm and switches off chosen circuits. Without it, the IET records that up to 230 volts can appear on earthed metalwork and up to 400 volts on single-phase equipment.
- Detecting a lost neutral or broken PEN at the incoming supply and at each distribution board
- Raising the alarm when earthed or bonded metalwork picks up voltage
- Alerting by text, email and building management system
- Switching off chosen circuits automatically or remotely, and linking to the fire alarm
- Covering the whole building, not a single car charger
- One accountable owner from the first alert to the network operator's repair
The challenge
Why is a broken PEN dangerous?
On a PME supply, one network conductor, the PEN, carries both the neutral and the protective earth. A break loses both at once, which is what lets voltage appear where it should never be.
The IET records that a broken PEN can put up to 230 volts on metalwork connected to the earthing terminal, and, where the break is on a three-phase section, up to 400 volts across single-phase installations built for 230. Pipework and other bonded metalwork can become live, and connected equipment is exposed to a voltage it was never designed for.
In March 2023 a single network neutral fault sent up to 415 volts into around 500 homes across 20 streets in one English town, damaging appliances and boilers.
PEN fault protection is already routine for outdoor car charging, because the Wiring Regulations require it there. Everywhere else in a building, nothing requires it, and a periodic inspection shows the installation only on the day it is tested.
How it works
What does whole-building PEN fault protection do?
It watches the supply at the intake and at each distribution board, so a lost neutral, a broken PEN or live metalwork is known the moment it happens.
When the neutral is lost, the PEN breaks, bonded metalwork picks up voltage or the supply runs out of range, the alarm goes out by text and email and to your building management system. Chosen circuits can be switched off automatically or remotely, and the fire alarm can be linked in.
Which circuits drop and which must stay on is designed with you for your building, not left as a default. We then own the response: answering the alarm, deciding what is safe to leave running, telling the people in the building, and getting the network operator out to repair the conductor.
What you get
Protection that reaches beyond the charger
Risk
The whole building watched
The intake and every distribution board, not one circuit, so a fault anywhere on the supply is seen.
Risk
Chosen loads isolated
Circuits you have chosen switched off on a fault, automatically or remotely, with a fire alarm link if you want one.
Obligation
An event record
Each alert and the response kept on record for your safety file and anyone who inspects you.
Risk
One owner of the response
Alarm, isolation, the people in the building and the network repair, handled by one accountable party.
Evidence
What the evidence shows about the hazard
These figures describe the fault and its effect, from the IET and a network operator. They are not our results.
230 VCan appear on earthed metalwork when the PEN breaks (IET, Wiring Matters, March 2021)
400 VCan reach single-phase equipment when the break is on a three-phase section (IET, same)
500 homesSupplied with up to 415 volts by one network neutral fault, March 2023 (the network operator's own statement)
Where it applies
Where whole-building protection matters most
Compliance
The compliance you carry
The UK environmental and safety duties that commonly reach broken neutral protection. Open any one for what it requires, the deadlines, what is at stake, and how to evidence control. Every entry is sourced.
PRS electricalObligationRiskElectrical safety standards in private rented homes (England Regulations 2020)
What you must doHave the electrical installation inspected and tested by a qualified person at least every five years, and act on what the inspection finds.
Applies toPrivate landlords letting homes in England.
When it bitesThroughout every tenancy, with the installation inspected and tested at least every five years.
DeadlinesIn force 1 June 2020; new tenancies from 1 July 2020; existing tenancies from 1 April 2021
What is at stakeA local authority may impose a financial penalty of up to GBP 30,000 per breach.
How to evidence itA current inspection report for each home and a record of any remedial work completed.
Legal basisElectrical Safety Standards in the Private Rented Sector (England) Regulations 2020 (SI 2020/312). Issued by Ministry of Housing, Communities and Local Government; enforced by local housing authorities.
Keep watch on the supply between inspections, so a fault that arrives after the test is known the day it happens.
Social rented electricalObligationRiskElectrical safety in social rented homes (England, SI 2025/1043)
What you must doInspect and test installations before a tenancy and at regular intervals, check provided electrical equipment at intervals of no more than five years, put unsafe equipment right within 28 days, and keep and supply the records.
Applies toRegistered providers of social housing in England.
When it bitesBefore each tenancy and at regular intervals throughout it.
DeadlinesIn force 1 November 2025; from 1 May 2026 for tenancies granted before 1 December 2025
What is at stakeNo penalty figure for the social rented extension was confirmed in our review; compliance is also assessed against the Regulator of Social Housing consumer standards.
How to evidence itInspection reports, equipment check records and remedial records held for each property.
Legal basisElectrical Safety Standards in the Private Rented Sector (England) (Amendment) (Extension to the Social Rented Sector) Regulations 2025 (SI 2025/1043). Issued by Ministry of Housing, Communities and Local Government.
Add a continuous watch on each block's supply to the inspection programme, with every event recorded against the building.
Awaab's LawObligationRiskAwaab's Law Phase 2: electrical hazards in social homes
What you must doInvestigate and make safe an emergency hazard within 24 hours. Investigate a significant hazard within 10 working days and complete safety work within 5 working days of the investigation concluding. It is a duty to act once aware, not a duty to monitor.
Applies toSocial landlords in England.
When it bitesFrom 30 November 2026, once the landlord is aware of a hazard presenting a significant risk of harm, including electrical hazards and fire and explosions.
DeadlinesIn force 30 November 2026
What is at stakeNo fine figure confirmed in our review; the duties are enforceable by tenants and sit alongside the regulator's consumer standards.
How to evidence itA record of when each hazard became known, the investigation, and the safety work, measured against the statutory timescales.
Legal basisHazards in Social Housing (Prescribed Requirements) (England) (Amendment) Regulations 2026. Issued by Ministry of Housing, Communities and Local Government.
An alarm makes you aware sooner, and we build the out-of-hours response so the hazard is being made safe as soon as the clock starts.
EAWRObligationRiskElectricity at Work Regulations 1989 (duty holders)
What you must doComply with the Regulations in so far as they relate to matters within your control; employees must co-operate. A network fault is outside your control, but its effects inside your building are not.
Applies toEvery employer and self-employed person, for electrical systems within their control, in any workplace from a school or care home to a hotel or office.
When it bitesContinuously, wherever people work with or near an electrical system you control.
DeadlinesOngoing (continuous duty)
What is at stakeEnforced by the HSE under health and safety law.
How to evidence itClear responsibility for each installation, current inspection and maintenance records, and a record of how supply faults are handled.
Legal basisElectricity at Work Regulations 1989 (SI 1989/635), regulation 3. Issued by Health and Safety Executive.
Know the moment the supply to a building you are responsible for turns unsafe, and have one party own the response.
BS 7671 722ObligationRiskPEN fault protection for outdoor EV charging (BS 7671 regulation 722.411.4.1)
What you must doProvide protection against the touch voltage an open PEN conductor can cause, by a device that disconnects the live and protective conductors, or by an earth electrode arrangement.
Applies toElectric vehicle charge points located outdoors, or likely to charge a vehicle outdoors, on a PME (TN-C-S) supply.
When it bitesOn installing a charge point in that situation.
DeadlinesRequired since Amendment 1 (2020) and retained since; Amendment 4 is reported to become the only current version on 15 October 2026
What is at stakeA British Standard rather than a statute; it is the reference used to show an installation meets the statutory duties.
How to evidence itThe installation certificate recording the protective measure used.
Legal basisBS 7671, the IET Wiring Regulations, regulation 722.411.4.1; product standard IET 01:2024 for open-PEN detection devices. Issued by IET and BSI.
The same fault the Wiring Regulations guard against at the car charger can reach every other circuit in the building. We watch the whole supply.
Before you commit
What this is, and what it is not
Here is the position plainly.
This does not repair the network's conductor, which belongs to the network operator. It does not replace your periodic inspection, and on its own it does not make a building compliant with anything. It will not promise that no fault ever causes harm. It watches the supply continuously, raises the alarm, switches off what you have chosen, and puts one party in charge of the response. Where a site takes its supply at high voltage through its own transformer, the exposure is different, and the assessment will say so.
The assessment tells you first whether this fault can reach your building at all.
Questions answered
What is the difference between a lost neutral and a broken PEN?
On a PME supply the network uses one conductor, the PEN, for both neutral and protective earth. A broken PEN therefore loses both at once, which is what lets voltage appear on earthed metalwork. A lost neutral on a three-phase section can also push up to 400 volts onto single-phase equipment, according to the IET.
Is PEN fault protection a legal requirement?
The Wiring Regulations require it for electric vehicle charge points located outdoors on a PME supply. There is no equivalent requirement for a building's general installation. Protecting the rest of the building is part of taking reasonable steps for the people in it, not a legal mandate, and we will not tell you otherwise.
Do the RCDs in our boards protect against a broken neutral?
The Wiring Regulations require a dedicated measure against this fault for outdoor car charging, over and above the RCD protection those circuits already carry. That tells you how the standards body regards the fault. Ask your electrical designer what covers the rest of your building.
We already have PEN protection on our car chargers. Is that enough?
It protects the charging circuit it is fitted to. The same fault on the incoming supply reaches every other circuit in the building, which is what whole-building protection watches.
Who repairs the fault?
The network operator owns the conductor and repairs it. We make sure they are called the moment the fault is detected, and we manage the building's side of the response while they do.
Find out whether this fault can reach your building
Tell us about the building and how it is supplied. We will assess where a broken neutral could reach and what whole-building protection and response would look like, before you commit.
Speak to the Team
Tell us your challenge
Tell us the cost, the risk or the obligation you are facing. A senior member of our team will respond, in confidence, with how we would help.
Every enquiry is handled in strict confidence.