A lightning event does not automatically mean that every surge protective device must be replaced. It does mean that the affected protection points should be inspected and the result documented. The replacement decision depends on the status indicator, remote alarm, physical condition, backup protection and the consequence of leaving an uncertain SPD in service.
This page is an event-aftercare and replacement decision guide. It is not a live-circuit testing procedure. Cabinet inspection, isolation and replacement should be carried out by qualified personnel under the site's electrical safety rules.
Daftar Isi
Quick Answer: Should the SPD Be Replaced?
Not automatically. Replace the SPD immediately when its failure indicator has changed state, the remote alarm reports a fault, the housing or terminals show damage, or the manufacturer's permitted inspection method confirms an abnormal condition.
If the visual indication remains normal and the wider post-event inspection finds no abnormal condition, the SPD may remain in service. However, a conventional green window is a status indication, not a measurement of exact remaining surge capacity. [1] [2]
Use Three Decisions, Not Only “Green or Red”
Failure or damage is confirmed
Replace the affected cartridge or complete SPD before the protection point is returned to normal service.
An abnormal event is unresolved
Keep the point under investigation when backup protection operated, equipment was damaged or the event path is uncertain.
No abnormal condition is found
Keep the SPD in service after visual status, alarm, wiring, earthing and backup protection have been checked and recorded.
When Must an SPD Be Replaced After Lightning?
| Condition after the event | What it means for the decision | Required action |
|---|---|---|
| Indicator shows the manufacturer's failure or end-of-life state | The monitored protective module is no longer in its normal service state. | Replace the affected module or device. |
| Remote fault contact has changed state | One or more monitored modules may have disconnected after an overload or failure. | Locate the affected SPD and inspect it physically. Do not only clear the BMS or PLC alarm. |
| Cracks, melting, burn marks, deformation, soot, damaged terminals or a burnt smell | Thermal, electrical or mechanical damage may have occurred. | Keep isolated and replace the damaged component or complete SPD. |
| SPD backup fuse, MCB or other specified backup protection operated | The cause may involve the SPD, wiring, system voltage or protective-device coordination. | Investigate before replacing the fuse or resetting the breaker. |
| Indicator and remote contact are normal, with no visible or system abnormality | No monitored end-of-life state has been identified. | Complete the inspection, record the result and continue monitoring. |
| SPD appears normal, but inverters, PLCs, power supplies or communication equipment were damaged | The surge may have entered through another line or bypassed part of the protection concept. | Inspect all relevant power, signal, data and earthing paths. |
| Confirmed direct strike at a critical, remote or difficult-to-access site | The uncertainty and cost of another event may be more important than the price of planned replacement. | Apply the manufacturer and site risk policy; consider preventive replacement. |
Do not simply reset the backup breaker
Re-energising without checking the SPD, circuit and system voltage can restore power while leaving a protection mode unavailable—or expose a new replacement module to the same unresolved fault.
What Should Be Checked Before the Replacement Decision?
This is a decision checklist, not a detailed SPD test method. For electrical testing and failure diagnosis procedures, use the separate SPD failure inspection guide. Regular SPD inspection and documented lightning-protection maintenance are part of a complete protection programme. [1]
Isolate safely
Follow the site's lockout, verification and electrical safety procedure before opening the cabinet.
Record every indicator
Check each phase, DC pole and N-PE module rather than recording only the overall assembly.
Review remote alarms
Confirm the alarm time, cabinet, contact state and affected protection point.
Inspect the device and wiring
Look for damage, discoloration, loose terminals, damaged insulation and abnormal heating.
Check backup protection
Record whether the specified fuse, breaker or surge backup protector operated.
Check earthing and bonding
Inspect the SPD earth conductor, equipotential connection and visible earthing-system damage.
Check other entry paths
Include AC, PV DC, sensors, RS485, Ethernet, PoE, coaxial and other external lines.
Photograph before removal
Capture the indicator, nameplate, cartridge, base, wiring, backup protection and cabinet position.
Page boundary: this page answers what to replace after the checks. The separate failure page explains how to test and diagnose the SPD in more detail.
The SPD Indicator Is Still Green. Can It Stay in Service?
On a conventional SPD, a normal visual indicator generally shows that the monitored disconnector has not reported the device's defined failure state. Status indication and remote signalling are used to identify overloaded or disconnected protective modules so that they can be replaced. [1] [3]
What a normal indicator supports
- No monitored end-of-life state is currently displayed.
- The module may remain available for protection.
- Lightning alone is not sufficient evidence that this module has failed.
- The device can remain in service when the wider inspection is also normal.
What a green window cannot prove
- It does not show how much surge energy was absorbed.
- It does not calculate exact remaining service life.
- It does not verify every wiring and earthing connection.
- It does not confirm the condition of other SPDs or surge entry paths.
- It does not replace a site-specific risk assessment after a severe event.
For replacement confirmation, the indicator colour alone is not enough
To confirm a LEEYEE replacement cartridge or equivalent SPD, provide the complete nameplate, every indicator window, the cartridge and base model, system voltage, wiring configuration, backup protection and a full cabinet photo.
This allows the replacement decision to be separated into three possibilities: an exact cartridge replacement, a complete SPD replacement or a specification correction before the same problem is repeated.
A standard multimeter is not a remaining-life tester
A basic resistance or continuity check may identify some severe open- or short-circuit conditions, but it cannot reproduce the impulse tests used to verify an SPD's published performance. IEC product standards define performance and test requirements for SPDs. [4]
What Does an SPD Remote Alarm Mean After Lightning?
A conventional remote contact normally reports the monitored operating or failure state of the SPD. It should not automatically be treated as a lightning counter or a measurement of the energy discharged. Remote signalling allows a failed or disconnected module to be detected from a control room, which is especially useful at large or difficult-to-access installations. [1] [2]
Check after an alarm
- Whether the contact is normally open or normally closed.
- Which cabinet and SPD generated the alarm.
- Whether one module or several poles changed state.
- Whether the contact returns to normal after correct replacement.
- Whether the monitoring wiring and PLC or BMS input are operating correctly.
Avoid these mistakes
- Do not only acknowledge the software alarm.
- Do not assume every alarm proves one specific lightning strike caused the fault.
- Do not replace the module without checking the system condition.
- Do not ignore a repeated alarm after fitting the same specification.
For PLC terminal logic and contact wiring, see the SPD remote alarm and PLC connection guide.
Should Every SPD in the Same Cabinet Be Replaced?
No—not automatically. But every relevant module should be checked. A single failed cartridge does not prove that every other module is damaged. Likewise, one normal indicator does not prove that the entire cabinet or protection chain is unaffected.
| Situation | Minimum scope | When wider replacement may be justified |
|---|---|---|
| One failed cartridge | Check all poles, the N-PE module, base, terminals and backup protection. | Other cartridges have the same long service and surge history, or another outage is costly. |
| One affected distribution board | Check upstream and downstream SPDs in the coordinated protection arrangement. | Several loads or multiple protection stages were affected. |
| Solar PV plant | Check combiner boxes, inverter DC inputs, AC outputs and communication protection. | Several strings, inverters or monitoring devices were damaged. |
| Telecom or outdoor site | Check AC, DC, antenna, data, PoE and earthing paths. | The site is unmanned, difficult to access or repeatedly exposed. |
| Factory or process plant | Check power distribution, PLC power, signals, sensors and networks. | Controlled replacement costs less than an unexpected production shutdown. |
Replace One Cartridge, the Full Set or the Complete SPD?
Replace one cartridge
Appropriate when only one compatible pluggable module has failed and the base, terminals, remote mechanism and remaining modules are undamaged.
Replace the complete module set
Consider this after a severe common event, when all modules have the same long service history, or when the site's maintenance policy requires matched replacement.
Replace the complete SPD
Required when the device is non-pluggable, the base or terminals are damaged, remote signalling is unreliable or cartridge compatibility cannot be confirmed.
Pluggable products can support faster maintenance, but the replacement cartridge must match the correct product family and base. Product documentation commonly identifies specific replacement modules rather than treating all cartridges as interchangeable. [3]
See the SPD cartridge replacement guide dan pluggable SPD replacement guide for the physical replacement stage.
When Is Preventive Replacement Reasonable?
Preventive replacement means replacing a device even though no defined failure indication is visible. It is not a universal rule after every thunderstorm. It is a risk decision based on event severity, uncertainty, access difficulty and the consequence of another surge.
| Site condition | Typical approach |
|---|---|
| Ordinary indoor panel with no abnormal result | Record the inspection and continue normal monitoring. |
| Outdoor cabinet in a high-lightning area | Increase attention to enclosure condition, earthing, moisture, terminals and spare availability. |
| Large solar plant with repeat events | Maintain event records and stock compatible DC, AC and communication replacement modules. |
| Unmanned telecom station | Use remote alarms and a conservative spare-parts policy because site access may be delayed. |
| Continuous-process factory or critical facility | Compare controlled replacement cost with the potential cost of another unprotected event. |
| Confirmed direct strike with multiple equipment failures | Assess the complete coordinated lightning and surge protection system, not only one SPD. |
IEC application guidance addresses SPD selection, location and coordination for AC and PV systems, supporting a system-level rather than single-device view. [5] [6] [7]
How to Confirm the Correct Replacement SPD
Do not order a replacement only by matching the housing colour, module width or a single value such as “40 kA.” The replacement must match the system, application, SPD type, electrical ratings and base.
Technical data to confirm
- AC, PV DC, other DC or signal circuit
- Nominal system voltage
- Earthing system or DC topology
- Type 1, Type 1+2, Type 2 or Type 3
- Uc or Ucpv
- Iimp where applicable
- In and Imax
- Up voltage protection level
- Number of poles and protection modes
- 1P+N, 2P, 3+1, 4+0 or other topology
- Cartridge and base model
- Remote contact requirement
- Backup fuse, MCB or SCPD requirement
- Applicable standard and certificate scope
- Temperature and enclosure conditions
- OEM label or private-brand requirement
Photos that prevent a wrong order
- Full front view of the SPD assembly
- Close-up of every indicator window
- Side and top nameplate details
- Cartridge model number
- Base model and coding
- Wiring and earthing connections
- Backup fuse or circuit breaker
- Any burn marks, cracks or damaged terminals
- Full cabinet and application location
What Else Should Be Checked at Different Sites?
Solar PV systems
Check DC combiner boxes, inverter DC inputs, inverter AC outputs, distribution boards, RS485, sensors, monitoring gateways and Ethernet lines.
Factory control systems
Check main and sub-distribution SPDs, PLC power supplies, I/O circuits, field sensors and communication cables that leave the control area.
Telecom stations
Include the AC supply, rectifier, -48 V DC system, antenna and coaxial lines, PoE, Ethernet, alarms and equipotential bonding.
Panel builders and EPC teams
Before supplying the same model, confirm whether incorrect voltage selection, backup coordination, wiring layout or system overvoltage contributed to the event.
Need to Confirm an SPD Replacement Model?
Send LEEYEE the nameplate, indicator status, system voltage, cartridge and base model, backup protection and cabinet photos. We can help determine whether the requirement is a replacement cartridge, a complete SPD or a corrected specification.
SPD Replacement After Lightning: FAQ
Does every SPD need to be replaced after a lightning strike?
No. Replace the SPD when its status indication, remote alarm, physical condition or approved inspection result shows that it is no longer suitable for service. A documented normal result may allow it to remain in operation.
Can an SPD stay in service if its indicator is still green?
Yes, when the complete post-event inspection is normal. The green indication generally means the monitored failure state has not been reached, but it does not calculate exact remaining surge capacity.
Does an SPD remote alarm prove that lightning damaged it?
Not by itself. A conventional remote contact normally reports the device's monitored status. Inspect the SPD locally and investigate the event before deciding the cause.
Can the SPD backup breaker simply be reset?
Not before inspection. The breaker may have operated because of SPD failure, a wiring fault, short circuit, abnormal system voltage or unsuitable coordination.
Should all modules in a three-phase SPD be replaced together?
Not automatically. One compatible cartridge can be replaced when only that module failed and the base and remaining modules are undamaged. Full-set replacement is a maintenance and risk decision.
What is needed to order the correct replacement module?
Confirm the application, system voltage, Uc or Ucpv, SPD type, Iimp, In, Imax, Up, pole configuration, cartridge, base, remote contact and backup protection.
Continue the SPD Troubleshooting Process
Referensi Teknis
- Phoenix Contact, Fundamentals for Surge Protection. Covers SPD maintenance, regular inspection, status indicators, remote signalling and replacement of overloaded protection modules. View source.
- Phoenix Contact, ImpulseCheck: Intelligent Monitoring of Surge Protection. Discusses condition monitoring and the limitations of relying only on a conventional status indication. View source.
- ABB Furse, ESP Type 1 and Type 2 Surge Protection Series Product Guide. Shows defined replacement modules, pluggable protection construction and remote-contact options. View source.
- IEC 61643-11:2025, Low-voltage Surge Protective Devices—Part 11: SPDs Connected to AC Low-Voltage Power Systems—Requirements and Test Methods. View IEC record.
- IEC 61643-12:2020, Selection, Operation, Location and Coordination Principles for AC SPDs. View IEC record.
- IEC 61643-31:2018, Requirements and Test Methods for SPDs for Photovoltaic Installations. View IEC record.
- IEC 61643-32:2017, Selection, Installation and Coordination of SPDs for Photovoltaic Systems. View IEC record.
