A replacement surge protective device (SPD) module may look like a small spare part, but a close visual match is not enough to establish that it fits a particular base or meets the original installation’s requirements. For distributors and purchasing teams, the practical challenge is to identify the installed assembly, specify the correct spare and retain the evidence behind the choice.
Start by asking the end customer for the original manufacturer and exact part numbers for both the complete SPD and the removable module, where applicable. Obtain the manufacturer’s documentation before offering a substitute. Some SPDs use a replaceable plug and base; others require a different service approach. The following checks help turn an incomplete spare-parts request into a clear enquiry.
1. Identify the installed assembly, not just the module colour
Ask for clear photographs of the complete device in its installed position and of the accessible nameplate. Record the manufacturer, product family, complete device code and any revision or ordering suffix shown. If the module and base carry separate codes, record both.
Do not infer compatibility from a similar front profile, indicator window or enclosure colour. Schneider Electric explicitly states that spare cartridges from its Acti 9 range are not compatible with its older Multi 9 surge arresters. This is an example from that manufacturer; it does not establish compatibility for other brands or models. Schneider Electric
If a nameplate is unreadable or a suffix is missing, keep the request open for identification. A proposed part number should be checked against the exact manufacturer’s catalogue or written confirmation for the installed assembly.
2. Confirm that a replacement module is actually offered
A photograph of a modular-looking device does not by itself establish that the protective element is a separately orderable spare. Ask for the original manual or a current manufacturer parts listing, and distinguish among:
- the complete SPD assembly;
- a base element;
- a replacement protection module or cartridge; and
- any monitoring or signalling accessories.
For example, Phoenix Contact identifies a particular plug as a replacement part for specified base elements; DEHN describes a named product family with a base and plug-in module. These are manufacturer-specific examples, not proof that another product uses the same construction. Phoenix Contact, DEHN
When discussing the Soltree AC SPD range, ask which exact models, complete assemblies and spare modules are available. Do not assume a module is sold separately until the supplier confirms it.
3. Match the electrical application and documented ratings
Obtain the installation details and original product documents needed by the responsible electrical professional. Useful comparison points include whether the application is AC or DC, the system and earthing arrangement, the declared SPD type or classification, the number of poles, and the ratings specified on the original product documents.
Where stated in the applicable manufacturer documentation, record maximum continuous operating voltage (Uc), protective voltage level (Up), and relevant discharge-current ratings. These labels are not interchangeable. The choice also depends on the application and protective coordination, so do not select a replacement using a single number alone. Schneider Electric’s selection guidance covers SPD type, voltage protection level, discharge-current characteristics and coordination. The Phoenix Contact and DEHN product examples separately list Uc for their stated models. Phoenix Contact, DEHN, Schneider Electric
Compare the candidate’s complete data sheet against the original requirements. An identical-looking voltage marking is not a substitute for a documented match to the base and application. If the existing device’s specification cannot be established, request a review rather than guessing.
4. Check the exact module-to-base compatibility
Ask the manufacturer or authorised source to identify the permitted module for the exact base and series, including revision and suffix where relevant. Keep the compatible part number and supporting document with the quotation.
A manufacturer’s information may list compatible components by family or specific product reference. Never imply interchangeability across manufacturers or across product generations unless that combination is explicitly supported by the relevant manufacturer. If the answer is uncertain, mark the quote “compatibility to be confirmed” and avoid presenting it as a direct replacement.
5. Review indication and monitoring requirements
Ask whether the existing assembly uses a local status indication, remote signalling or a separate monitoring accessory. Record what the site expects to retain and compare the original and proposed parts using the manufacturer’s documentation.
Indicators and contacts differ by product. A visual flag on one device should not be assumed to have the same meaning, colour sequence or behaviour on another. In the DEHNguard SE H … FM example, the manufacturer lists operating-state/fault indication and a remote signalling contact for the stated assembly; those details apply to that named product, not to every SPD. DEHN
6. Define the quantity and delivery scope
Clarify whether the enquiry is for individual modules, complete assemblies or a mixed spare-parts list. Record the requested quantity for each manufacturer part number and note whether bases, signalling accessories, manuals or packaging labels are expected.
Ask the supplier to confirm the available part, ordering unit and documents in writing. Stock, lead time, pricing, minimum order quantity and aftermarket support should be treated as quotation details to confirm for the actual order, not assumptions based on a generic catalogue page.
7. Keep a simple identification and traceability record
A useful record can contain:
| Item | Information to collect |
|---|---|
| Installed device | Manufacturer, product family, assembly model and revision |
| Replaceable part | Module and base part numbers, if separately identified |
| Application | AC or DC, system details and original documented requirements |
| Matching evidence | Manufacturer compatibility listing, manual or written confirmation |
| Monitoring | Required local indication or remote signalling details |
| Order | Correct part number, quantity, scope and destination |
| Outstanding questions | Missing photographs, unreadable markings or unconfirmed compatibility |
Do not include customer site information in a public page without permission. The goal is to make the replacement request traceable and reduce errors between identification, quotation and delivery.
Before placing an order
A good spare-parts enquiry describes the original assembly and the evidence for the proposed replacement. The installation’s responsible electrical professional should determine the appropriate product and service procedure using the applicable manufacturer instructions and local requirements. This purchasing checklist is not a wiring or replacement procedure.
If you are comparing AC surge protection products or need information about a particular Soltree model, contact Soltree with the model, photographs, application, requested quantity and destination. Ask whether a separate replacement module is available and which assembly it is intended for. For a broader enquiry template, see How to Prepare an RFQ for Low-Voltage Electrical Products.
Sources
- Schneider Electric, Are spare cartridges from Acti 9 compatible with older Multi 9 surge arresters? — named product ranges are not interchangeable.
- Phoenix Contact, GDT-US-NG/40-P surge protection replacement plug — a specific replacement plug is identified for use with named base elements.
- DEHN, DEHNguard SE H … FM — manufacturer-specific example of a base/module assembly and stated indication and signalling details.
- Schneider Electric, How to select an SPD for an entire installation — selection characteristics and further coordination resources.
