✨ New Arrivals Just Dropped!Explore
Projoy Firefighter Safety Switch 4 Pole 2 Strings with MC4 40A per String incl. FB Function
HomeStore

Projoy Firefighter Safety Switch 4 Pole 2 Strings with MC4 40A per String incl. FB Function

Projoy Firefighter Safety Switch 4 Pole 2 Strings with MC4 40A per String incl. FB Function

The Projoy PEFS-EL Firefighter Safety Switch — 4-Pole, 2-String, 40A with FB Function is a string-level rapid shutdown device for residential rooftop solar PV systems with up to two strings. Mounted close to the panel array, it disconnects the high-voltage DC cable run (up to 1500V DC) between the panels and inverter in the event of fire, emergency or grid loss — the run that remains live as long as sunlight falls on the panels, even with the inverter switched off. Shutdown is triggered automatically by AC grid loss (after 5 seconds), by an internal temperature sensor (≥70°C), or manually via an emergency stop button. Auto-resets when AC power is restored. This variant includes the FB feedback contact (24V DC, 300mA) for inverter shutdown confirmation. Pre-wired with MC4 connectors. Rated IP65, UL 94 V-0. Certified to EN 60947-1&3. Controlled via AC circuit — no Wi-Fi, no RF, no additional networking.

4-pole
2 Strings
40A
Per String
1500V
Max DC
IP65
Rated
FB
Feedback
EN 60947
Certified
⚠ Qualified Installer Required: PV system components must be installed by a suitably qualified and competent person in accordance with BS 7671, IEC 60364-7-712 and MCS installation standards.
Key Features
2-String 40A — Right-Sized for Most UK Residential Arrays
The majority of residential rooftop solar installations in the UK use one or two strings feeding a single-phase string inverter. The 40A per string rating comfortably covers virtually all single-string configurations (most panels have an Isc below 15A, and multi-panel strings rarely exceed 15A). The 2-string, 4-pole variant is the most common configuration for 2–6 kWp systems.
1–2 string systems2–6 kWp40A per string
Three Independent Shutdown Triggers — Any One Alone Is Sufficient
The PEFS-EL responds to three separate events, each capable of triggering automatic shutdown independently: (1) AC grid loss for more than 5 seconds — matches international firefighter procedure of cutting AC supply first before tackling the fire; (2) Internal enclosure temperature reaching 70°C — detected by a built-in sensor that monitors the enclosure interior in real time, triggering shutdown before the enclosure becomes a fire hazard itself; (3) Manual emergency stop button on the enclosure face for immediate on-site override.
AC loss ≥5s70°C temp sensorManual stop button
Automatic Reset — Resumes Generation After Routine Grid Outages
Unlike a one-shot fuse, the PEFS-EL resets automatically when AC power is restored after any automatic shutdown. For routine grid outages, ISP maintenance, load shedding or momentary supply interruptions, the system will re-close and resume generation without any manual intervention. Manual reset is only required after activation of the emergency stop button.
Auto-reset on AC restoreNo manual reset for grid outagesMinimises lost generation
Motor-Driven Energy-Storage Spring — 5ms Arc-Quench
Each pole is opened by a motor-driven energy-storage spring mechanism that releases on trigger, driving the contacts apart in under 5 milliseconds. DC arcs have no zero-crossing point and sustain indefinitely if contacts separate slowly — the 5ms response is specifically designed to stretch and quench the DC arc before it can cause contact damage, tracking or fire. Self-cleaning contacts reduce resistance build-up over the device lifetime.
5ms trip responseEnergy-storage springDC arc-quench mechanismSelf-cleaning contacts
MC4 Connectors — Direct Plug-In to Panel String Cables
DC string inputs are pre-wired with MC4 connectors — the universal standard connector used on virtually all solar panels. No stripping, crimping or ferrule insertion required on the DC side. The AC control cable enters via a standard IP65 cable gland.
MC4 pre-wiredNo DC termination workAC gland entry
IP65 Polycarbonate Enclosure — V-0 Flame Retardant
The enclosure is IP65-rated polycarbonate — fully dustproof and protected against water jets from any direction. The body material carries a UL 94 V-0 flame-retardant rating, meaning it will not propagate flame even if exposed to a direct ignition source. Suitable for rooftop, loft or external wall mounting.
IP65UL 94 V-0 flame retardantOutdoor-rated
AC-Circuit Controlled — No Wi-Fi, No RF, No Pairing Required
The PEFS-EL is controlled entirely by the existing AC supply circuit. When AC is present, the switch is closed. When AC drops for 5 seconds, the switch opens. No wireless communication module, no pairing sequence, no signal cable to run from the roof. The control logic is deterministic and immune to network failure — critical for a life-safety device.
AC-circuit logicNo Wi-Fi / RFDeterministic failsafeNo configuration
Technical Specifications
PEFS-EL — 4-Pole 2-String 40A
Number of Poles 4 (2 per string, 2 strings)
Number of Strings 2
Rated Current per String 40A
Max Loop Voltage (DC) 1500V DC
String Voltage Range 300–1500V DC
AC Control Voltage 100–270V AC
AC Nominal Voltage 230V AC
Feedback (FB) Contact Yes — 24V DC, 300mA max
DC Connector Type MC4 (pre-wired)
Triggers and Behaviour
Auto Shutdown: AC Loss Opens after AC loss ≥5 seconds
Auto Shutdown: Temperature Opens when internal temp ≥70°C
Manual Shutdown Emergency stop button on enclosure
Auto Reset Yes — auto-closes when AC power restored
Switching Speed <5ms (energy-storage spring mechanism)
Physical and Environmental
Protection Rating IP65
Flame Retardant Rating UL 94 V-0 (enclosure body)
Operating Temperature −20°C to +50°C
Auto-Trip Temperature +70°C (internal enclosure)
Storage Temperature −40°C to +85°C
Protection Class Class II
Standards and Certifications
Test Standard EN 60947-1 & 3
Certifications CE, ISO 9001, ISO 14001
DC Switch Standard IEC 60947-3 (ed.3.2):2015, UL508i, GB14048.3
Utilisation Category DC-PV0 / DC-PV1
Mechanical Life
Operations (total) 10,000
Operations under load (PV1) >1,500
Manufacturer
Manufacturer Projoy Electric Co., Ltd.
Frequently Asked Questions
Where in the PV system is this installed?
The PEFS-EL is mounted close to the panel array, between the string cables and the inverter input. The AC control cable is connected to a permanent live feed from the distribution board or inverter AC output. MC4 connectors on the DC inputs plug directly into the panel string cables. Position it so the emergency stop button is accessible, typically in the loft or near the array.
What is the FB feedback function and do I need it?
The FB (feedback) contact is a dry-contact auxiliary output that signals the switch open/closed state to the inverter or monitoring system, allowing the inverter to confirm that the shutdown device has physically operated. Some inverter manufacturers require this for compliance; check your inverter installation manual. If your inverter does not require feedback confirmation, the non-FB variant is sufficient. This variant includes the FB contact (24V DC, 300mA max).
Will a routine power cut reset the system automatically?
Yes. The PEFS-EL resets automatically when the AC supply is restored. After a normal grid outage, the switch re-closes and PV generation resumes without manual action. Only activation of the emergency stop button requires a manual reset.
Does this meet UK Building Regulations or MCS requirements?
The PEFS-EL is certified to EN 60947-1 and 60947-3 and CE-marked. BS 7671 requires DC isolation on PV installations. For specific regulatory compliance, consult the current MCS standards and your DNO requirements. Always verify with your qualified installer.
Is a separate AC isolator also required?
Yes. The PEFS-EL handles DC-side string isolation only. A separate AC isolator at the inverter output remains required by BS 7671 and MCS. Projoy’s PEAS series AC isolators (also available here) are designed for this purpose.
Related Products
Projoy Battery Isolator with Enclosure (PEBS-L)
DC MCB for battery-inverter circuits
Projoy DC Surge Protector (PESP)
SPD for DC PV string protection
$94.48

Original: $269.93

-65%
Projoy Firefighter Safety Switch 4 Pole 2 Strings with MC4 40A per String incl. FB Function—

$269.93

$94.48

More Images

Projoy Firefighter Safety Switch 4 Pole 2 Strings with MC4 40A per String incl. FB Function - Image 2

Projoy Firefighter Safety Switch 4 Pole 2 Strings with MC4 40A per String incl. FB Function

The Projoy PEFS-EL Firefighter Safety Switch — 4-Pole, 2-String, 40A with FB Function is a string-level rapid shutdown device for residential rooftop solar PV systems with up to two strings. Mounted close to the panel array, it disconnects the high-voltage DC cable run (up to 1500V DC) between the panels and inverter in the event of fire, emergency or grid loss — the run that remains live as long as sunlight falls on the panels, even with the inverter switched off. Shutdown is triggered automatically by AC grid loss (after 5 seconds), by an internal temperature sensor (≥70°C), or manually via an emergency stop button. Auto-resets when AC power is restored. This variant includes the FB feedback contact (24V DC, 300mA) for inverter shutdown confirmation. Pre-wired with MC4 connectors. Rated IP65, UL 94 V-0. Certified to EN 60947-1&3. Controlled via AC circuit — no Wi-Fi, no RF, no additional networking.

4-pole
2 Strings
40A
Per String
1500V
Max DC
IP65
Rated
FB
Feedback
EN 60947
Certified
⚠ Qualified Installer Required: PV system components must be installed by a suitably qualified and competent person in accordance with BS 7671, IEC 60364-7-712 and MCS installation standards.
Key Features
2-String 40A — Right-Sized for Most UK Residential Arrays
The majority of residential rooftop solar installations in the UK use one or two strings feeding a single-phase string inverter. The 40A per string rating comfortably covers virtually all single-string configurations (most panels have an Isc below 15A, and multi-panel strings rarely exceed 15A). The 2-string, 4-pole variant is the most common configuration for 2–6 kWp systems.
1–2 string systems2–6 kWp40A per string
Three Independent Shutdown Triggers — Any One Alone Is Sufficient
The PEFS-EL responds to three separate events, each capable of triggering automatic shutdown independently: (1) AC grid loss for more than 5 seconds — matches international firefighter procedure of cutting AC supply first before tackling the fire; (2) Internal enclosure temperature reaching 70°C — detected by a built-in sensor that monitors the enclosure interior in real time, triggering shutdown before the enclosure becomes a fire hazard itself; (3) Manual emergency stop button on the enclosure face for immediate on-site override.
AC loss ≥5s70°C temp sensorManual stop button
Automatic Reset — Resumes Generation After Routine Grid Outages
Unlike a one-shot fuse, the PEFS-EL resets automatically when AC power is restored after any automatic shutdown. For routine grid outages, ISP maintenance, load shedding or momentary supply interruptions, the system will re-close and resume generation without any manual intervention. Manual reset is only required after activation of the emergency stop button.
Auto-reset on AC restoreNo manual reset for grid outagesMinimises lost generation
Motor-Driven Energy-Storage Spring — 5ms Arc-Quench
Each pole is opened by a motor-driven energy-storage spring mechanism that releases on trigger, driving the contacts apart in under 5 milliseconds. DC arcs have no zero-crossing point and sustain indefinitely if contacts separate slowly — the 5ms response is specifically designed to stretch and quench the DC arc before it can cause contact damage, tracking or fire. Self-cleaning contacts reduce resistance build-up over the device lifetime.
5ms trip responseEnergy-storage springDC arc-quench mechanismSelf-cleaning contacts
MC4 Connectors — Direct Plug-In to Panel String Cables
DC string inputs are pre-wired with MC4 connectors — the universal standard connector used on virtually all solar panels. No stripping, crimping or ferrule insertion required on the DC side. The AC control cable enters via a standard IP65 cable gland.
MC4 pre-wiredNo DC termination workAC gland entry
IP65 Polycarbonate Enclosure — V-0 Flame Retardant
The enclosure is IP65-rated polycarbonate — fully dustproof and protected against water jets from any direction. The body material carries a UL 94 V-0 flame-retardant rating, meaning it will not propagate flame even if exposed to a direct ignition source. Suitable for rooftop, loft or external wall mounting.
IP65UL 94 V-0 flame retardantOutdoor-rated
AC-Circuit Controlled — No Wi-Fi, No RF, No Pairing Required
The PEFS-EL is controlled entirely by the existing AC supply circuit. When AC is present, the switch is closed. When AC drops for 5 seconds, the switch opens. No wireless communication module, no pairing sequence, no signal cable to run from the roof. The control logic is deterministic and immune to network failure — critical for a life-safety device.
AC-circuit logicNo Wi-Fi / RFDeterministic failsafeNo configuration
Technical Specifications
PEFS-EL — 4-Pole 2-String 40A
Number of Poles 4 (2 per string, 2 strings)
Number of Strings 2
Rated Current per String 40A
Max Loop Voltage (DC) 1500V DC
String Voltage Range 300–1500V DC
AC Control Voltage 100–270V AC
AC Nominal Voltage 230V AC
Feedback (FB) Contact Yes — 24V DC, 300mA max
DC Connector Type MC4 (pre-wired)
Triggers and Behaviour
Auto Shutdown: AC Loss Opens after AC loss ≥5 seconds
Auto Shutdown: Temperature Opens when internal temp ≥70°C
Manual Shutdown Emergency stop button on enclosure
Auto Reset Yes — auto-closes when AC power restored
Switching Speed <5ms (energy-storage spring mechanism)
Physical and Environmental
Protection Rating IP65
Flame Retardant Rating UL 94 V-0 (enclosure body)
Operating Temperature −20°C to +50°C
Auto-Trip Temperature +70°C (internal enclosure)
Storage Temperature −40°C to +85°C
Protection Class Class II
Standards and Certifications
Test Standard EN 60947-1 & 3
Certifications CE, ISO 9001, ISO 14001
DC Switch Standard IEC 60947-3 (ed.3.2):2015, UL508i, GB14048.3
Utilisation Category DC-PV0 / DC-PV1
Mechanical Life
Operations (total) 10,000
Operations under load (PV1) >1,500
Manufacturer
Manufacturer Projoy Electric Co., Ltd.
Frequently Asked Questions
Where in the PV system is this installed?
The PEFS-EL is mounted close to the panel array, between the string cables and the inverter input. The AC control cable is connected to a permanent live feed from the distribution board or inverter AC output. MC4 connectors on the DC inputs plug directly into the panel string cables. Position it so the emergency stop button is accessible, typically in the loft or near the array.
What is the FB feedback function and do I need it?
The FB (feedback) contact is a dry-contact auxiliary output that signals the switch open/closed state to the inverter or monitoring system, allowing the inverter to confirm that the shutdown device has physically operated. Some inverter manufacturers require this for compliance; check your inverter installation manual. If your inverter does not require feedback confirmation, the non-FB variant is sufficient. This variant includes the FB contact (24V DC, 300mA max).
Will a routine power cut reset the system automatically?
Yes. The PEFS-EL resets automatically when the AC supply is restored. After a normal grid outage, the switch re-closes and PV generation resumes without manual action. Only activation of the emergency stop button requires a manual reset.
Does this meet UK Building Regulations or MCS requirements?
The PEFS-EL is certified to EN 60947-1 and 60947-3 and CE-marked. BS 7671 requires DC isolation on PV installations. For specific regulatory compliance, consult the current MCS standards and your DNO requirements. Always verify with your qualified installer.
Is a separate AC isolator also required?
Yes. The PEFS-EL handles DC-side string isolation only. A separate AC isolator at the inverter output remains required by BS 7671 and MCS. Projoy’s PEAS series AC isolators (also available here) are designed for this purpose.
Related Products
Projoy Battery Isolator with Enclosure (PEBS-L)
DC MCB for battery-inverter circuits
Projoy DC Surge Protector (PESP)
SPD for DC PV string protection

Product Information

Shipping & Returns

Description

The Projoy PEFS-EL Firefighter Safety Switch — 4-Pole, 2-String, 40A with FB Function is a string-level rapid shutdown device for residential rooftop solar PV systems with up to two strings. Mounted close to the panel array, it disconnects the high-voltage DC cable run (up to 1500V DC) between the panels and inverter in the event of fire, emergency or grid loss — the run that remains live as long as sunlight falls on the panels, even with the inverter switched off. Shutdown is triggered automatically by AC grid loss (after 5 seconds), by an internal temperature sensor (≥70°C), or manually via an emergency stop button. Auto-resets when AC power is restored. This variant includes the FB feedback contact (24V DC, 300mA) for inverter shutdown confirmation. Pre-wired with MC4 connectors. Rated IP65, UL 94 V-0. Certified to EN 60947-1&3. Controlled via AC circuit — no Wi-Fi, no RF, no additional networking.

4-pole
2 Strings
40A
Per String
1500V
Max DC
IP65
Rated
FB
Feedback
EN 60947
Certified
⚠ Qualified Installer Required: PV system components must be installed by a suitably qualified and competent person in accordance with BS 7671, IEC 60364-7-712 and MCS installation standards.
Key Features
2-String 40A — Right-Sized for Most UK Residential Arrays
The majority of residential rooftop solar installations in the UK use one or two strings feeding a single-phase string inverter. The 40A per string rating comfortably covers virtually all single-string configurations (most panels have an Isc below 15A, and multi-panel strings rarely exceed 15A). The 2-string, 4-pole variant is the most common configuration for 2–6 kWp systems.
1–2 string systems2–6 kWp40A per string
Three Independent Shutdown Triggers — Any One Alone Is Sufficient
The PEFS-EL responds to three separate events, each capable of triggering automatic shutdown independently: (1) AC grid loss for more than 5 seconds — matches international firefighter procedure of cutting AC supply first before tackling the fire; (2) Internal enclosure temperature reaching 70°C — detected by a built-in sensor that monitors the enclosure interior in real time, triggering shutdown before the enclosure becomes a fire hazard itself; (3) Manual emergency stop button on the enclosure face for immediate on-site override.
AC loss ≥5s70°C temp sensorManual stop button
Automatic Reset — Resumes Generation After Routine Grid Outages
Unlike a one-shot fuse, the PEFS-EL resets automatically when AC power is restored after any automatic shutdown. For routine grid outages, ISP maintenance, load shedding or momentary supply interruptions, the system will re-close and resume generation without any manual intervention. Manual reset is only required after activation of the emergency stop button.
Auto-reset on AC restoreNo manual reset for grid outagesMinimises lost generation
Motor-Driven Energy-Storage Spring — 5ms Arc-Quench
Each pole is opened by a motor-driven energy-storage spring mechanism that releases on trigger, driving the contacts apart in under 5 milliseconds. DC arcs have no zero-crossing point and sustain indefinitely if contacts separate slowly — the 5ms response is specifically designed to stretch and quench the DC arc before it can cause contact damage, tracking or fire. Self-cleaning contacts reduce resistance build-up over the device lifetime.
5ms trip responseEnergy-storage springDC arc-quench mechanismSelf-cleaning contacts
MC4 Connectors — Direct Plug-In to Panel String Cables
DC string inputs are pre-wired with MC4 connectors — the universal standard connector used on virtually all solar panels. No stripping, crimping or ferrule insertion required on the DC side. The AC control cable enters via a standard IP65 cable gland.
MC4 pre-wiredNo DC termination workAC gland entry
IP65 Polycarbonate Enclosure — V-0 Flame Retardant
The enclosure is IP65-rated polycarbonate — fully dustproof and protected against water jets from any direction. The body material carries a UL 94 V-0 flame-retardant rating, meaning it will not propagate flame even if exposed to a direct ignition source. Suitable for rooftop, loft or external wall mounting.
IP65UL 94 V-0 flame retardantOutdoor-rated
AC-Circuit Controlled — No Wi-Fi, No RF, No Pairing Required
The PEFS-EL is controlled entirely by the existing AC supply circuit. When AC is present, the switch is closed. When AC drops for 5 seconds, the switch opens. No wireless communication module, no pairing sequence, no signal cable to run from the roof. The control logic is deterministic and immune to network failure — critical for a life-safety device.
AC-circuit logicNo Wi-Fi / RFDeterministic failsafeNo configuration
Technical Specifications
PEFS-EL — 4-Pole 2-String 40A
Number of Poles 4 (2 per string, 2 strings)
Number of Strings 2
Rated Current per String 40A
Max Loop Voltage (DC) 1500V DC
String Voltage Range 300–1500V DC
AC Control Voltage 100–270V AC
AC Nominal Voltage 230V AC
Feedback (FB) Contact Yes — 24V DC, 300mA max
DC Connector Type MC4 (pre-wired)
Triggers and Behaviour
Auto Shutdown: AC Loss Opens after AC loss ≥5 seconds
Auto Shutdown: Temperature Opens when internal temp ≥70°C
Manual Shutdown Emergency stop button on enclosure
Auto Reset Yes — auto-closes when AC power restored
Switching Speed <5ms (energy-storage spring mechanism)
Physical and Environmental
Protection Rating IP65
Flame Retardant Rating UL 94 V-0 (enclosure body)
Operating Temperature −20°C to +50°C
Auto-Trip Temperature +70°C (internal enclosure)
Storage Temperature −40°C to +85°C
Protection Class Class II
Standards and Certifications
Test Standard EN 60947-1 & 3
Certifications CE, ISO 9001, ISO 14001
DC Switch Standard IEC 60947-3 (ed.3.2):2015, UL508i, GB14048.3
Utilisation Category DC-PV0 / DC-PV1
Mechanical Life
Operations (total) 10,000
Operations under load (PV1) >1,500
Manufacturer
Manufacturer Projoy Electric Co., Ltd.
Frequently Asked Questions
Where in the PV system is this installed?
The PEFS-EL is mounted close to the panel array, between the string cables and the inverter input. The AC control cable is connected to a permanent live feed from the distribution board or inverter AC output. MC4 connectors on the DC inputs plug directly into the panel string cables. Position it so the emergency stop button is accessible, typically in the loft or near the array.
What is the FB feedback function and do I need it?
The FB (feedback) contact is a dry-contact auxiliary output that signals the switch open/closed state to the inverter or monitoring system, allowing the inverter to confirm that the shutdown device has physically operated. Some inverter manufacturers require this for compliance; check your inverter installation manual. If your inverter does not require feedback confirmation, the non-FB variant is sufficient. This variant includes the FB contact (24V DC, 300mA max).
Will a routine power cut reset the system automatically?
Yes. The PEFS-EL resets automatically when the AC supply is restored. After a normal grid outage, the switch re-closes and PV generation resumes without manual action. Only activation of the emergency stop button requires a manual reset.
Does this meet UK Building Regulations or MCS requirements?
The PEFS-EL is certified to EN 60947-1 and 60947-3 and CE-marked. BS 7671 requires DC isolation on PV installations. For specific regulatory compliance, consult the current MCS standards and your DNO requirements. Always verify with your qualified installer.
Is a separate AC isolator also required?
Yes. The PEFS-EL handles DC-side string isolation only. A separate AC isolator at the inverter output remains required by BS 7671 and MCS. Projoy’s PEAS series AC isolators (also available here) are designed for this purpose.
Related Products
Projoy Battery Isolator with Enclosure (PEBS-L)
DC MCB for battery-inverter circuits
Projoy DC Surge Protector (PESP)
SPD for DC PV string protection