Metal Fuse Switch 100A with 3 × Fuses & SPD (WFMS100/3FSP)
18th Ed. Compliant
2-Year Warranty
UK Stock
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The WFMS100/3FSP is a 100A metal switch fuse isolator with SPD, supplied complete with a Type 2 Surge Protection Device and 63A, 80A and 100A cartridge fuse options. It provides fused isolation and surge protection in one compact metal enclosure for installers building compliant EV, heat pump and distribution board...
The WFMS100/3FSP is a 100A metal switch fuse isolator with SPD, supplied complete with a Type 2 Surge Protection Device and 63A, 80A and 100A cartridge fuse options. It provides fused isolation and surge protection in one compact metal enclosure for installers building compliant EV, heat pump and distribution board supplies.
Designed for use as an upstream 100 amp fused isolator switch, this unit helps protect downstream equipment against overcurrent and transient overvoltage events while reducing the need for separate switch fuse and SPD assemblies. The pre-assembled format keeps the install cleaner and gives electricians a practical all-in-one incomer option.
Installer note: This unit is best positioned as a surge-protected fused incomer where the selected fuse rating, supply arrangement and downstream board specification have been checked against the installation design.
- 100A metal switch fuse isolator – suitable for upstream fused isolation
- Type 2 SPD included – provides surge protection for downstream circuits
- 63A, 80A and 100A cartridge fuses supplied – allows on-site fuse selection to suit the design
- Metal-clad enclosure – compact surface-mounted format for indoor installs
- Integrated isolation, fusing and surge protection – reduces separate components and board clutter
- Useful for EV, heat pump and distribution board supplies – where the specification calls for fused isolation with SPD protection
Switch Fuse with SPD for Protected Board Supplies
A switch fuse with SPD can be useful where an installer needs fused isolation and surge protection before a dedicated board or downstream consumer unit. This is common on installations where EV chargers, heat pumps, outbuildings or local distribution boards require a clearly protected supply arrangement.
The WFMS100/3FSP combines those functions in one enclosure, helping reduce the number of separate parts needed while keeping isolation, fusing and SPD status checking accessible in one place.
Compare Metal Fuse Switch Options
| Product | Includes | Best For |
|---|---|---|
| WFMS100 | 100A metal fuse switch | Basic fused isolation |
| WFMS100/3F | 100A switch fuse with 63A, 80A and 100A fuses | Fused isolation with selectable fuse rating |
| WFMS100/3FSP | 100A switch fuse, cartridge fuses and Type 2 SPD | Fused isolation with integrated surge protection |
| WFMS/3P | 125A 4 pole metal fuse switch | Three-phase board supplies |
The WFMS100/3FSP is a practical choice where a 100A fused isolator with surge protection is required before an EV-ready consumer unit, heat pump board or local distribution board.
What is this 100A switch fuse isolator used for?
It is used to provide fused isolation and surge protection before a suitable downstream board, such as an EV-ready consumer unit, heat pump board or local distribution board.
Does this unit include surge protection?
Yes. The WFMS100/3FSP includes an integrated Type 2 SPD to help protect downstream circuits from transient overvoltages.
What fuses are supplied with this switch fuse?
The unit is supplied with 63A, 80A and 100A cartridge fuse options, allowing the correct fuse rating to be selected for the installation design.
Is this a 3 phase fused isolator?
No. This product should not be treated as a 3 phase fused isolator unless the manufacturer specification confirms that use. For three-phase board supplies, see the WFMS/3P metal fuse switch.
Can this be used before an EV charger board?
Yes, where the circuit design requires a fused upstream isolator with surge protection and the selected fuse rating is suitable for the EV board supply.
Do I need a separate SPD if this unit is installed?
This unit includes a Type 2 SPD. Whether further SPD protection is needed depends on the wider installation design, board layout and circuit requirements.
- Model: WFMS100/3FSP
- Product Type: Metal Switch Fuse Isolator with SPD
- Main Switch Rating: 100A
- Isolation: Double pole
- Fuse Holder Type: 22 × 58mm cartridge fuse holder
- Fuses Supplied: 63A, 80A and 100A cartridge fuses
- Surge Protection: Type 2 SPD
- Enclosure: Metal-clad surface mount
- Dimensions (W × H × D): 160 × 240 × 112mm
- Ingress Protection: IP40
- Application: Fused isolation and surge protection for suitable EV, heat pump and distribution board supplies
- Standards: BS EN 60947-3 / BS EN 61643-11
This unit is supplied pre-assembled with the switch fuse, cartridge fuse options and SPD fitted. Final installation, fuse selection and commissioning must be carried out by a qualified electrician in accordance with the installation design and current BS 7671 requirements.
- Select the appropriate fuse rating before energising the circuit
- Confirm conductor sizing and downstream board rating before installation
- Verify the supply arrangement and prospective fault current are suitable for the device
- Keep SPD earth connections short and direct where possible
- Check SPD status indication during commissioning and future inspection
- Install indoors in a suitable accessible position for isolation and maintenance
Specification note: Do not select this unit on current rating alone. Fuse size, cable size, fault level, earthing arrangement and downstream equipment must all be checked before installation.
