Metal Fuse Switch 100A with 3 × Fuses & SPD (WFMS100/3FSP)
18th Ed. Compliant
2-Year Warranty
UK Stock
Free Delivery £30+
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The WFMS100/3FSP is a 100 A metal fuse switch supplied complete with three 22 × 58 mm cartridge fuses (63 A, 80 A & 100 A) and an integrated Type 2 Surge Protection Device (SPD). It delivers mains isolation, over-current protection, and surge suppression in one pre-assembled, regulation-ready enclosure —...
The WFMS100/3FSP is a 100 A metal fuse switch supplied complete with three 22 × 58 mm cartridge fuses (63 A, 80 A & 100 A) and an integrated Type 2 Surge Protection Device (SPD). It delivers mains isolation, over-current protection, and surge suppression in one pre-assembled, regulation-ready enclosure — ideal for domestic and commercial installs requiring 18th Edition Amendment 2 compliance.
Installer Tip: Use the WFMS100/3FSP as the incoming fused isolator for EV or heat-pump boards. The built-in SPD meets BS 7671 Reg 443.4, protecting connected circuits from transient overvoltages without needing a separate surge module in the consumer unit.
- 100 A double-pole switch-fuse assembly with built-in Type 2 SPD
- Supplied with three cartridge fuses (63 A / 80 A / 100 A) for on-site selection
- Compact steel enclosure with pre-drilled knockouts for quick fitting
- SPD status indicator + removable cartridge for simple testing and replacement
- BS EN 60947-3 & BS EN 61643-11 compliant
| Model | Main Switch | Fuses Included | Extras | Typical Use |
|---|---|---|---|---|
| WFMS100 | 100 A 2 Pole | – | – | Basic isolation only |
| WFMS100/3F | 100 A 2 Pole | 63 A / 80 A / 100 A | – | Fused mains protection |
| WFMS100/3FSP | 100 A 2 Pole | 63 A / 80 A / 100 A | Type 2 SPD | Surge-protected incomer |
| WFMS/3P | 125 A 4 Pole | 3 × Fuses | – | Three-phase boards |
Combining isolation, fusing, and surge suppression in one enclosure, this unit streamlines installs and reduces board clutter. It pairs perfectly with EV-ready consumer units or heat-pump distribution boards to deliver full Amendment 2 compliance from supply to final circuit.
What’s the benefit of the built-in SPD?
It provides immediate protection against transient overvoltages from lightning or switching surges, safeguarding sensitive electronics downstream without needing a separate surge module.
Can I replace the SPD cartridge?
Yes – the SPD module is removable and replaceable. The front window changes from green to red when replacement is required.
Is this unit 18th Edition compliant?
Yes – the integrated Type 2 SPD ensures compliance with BS 7671 Amendment 2 (Reg 443.4) for surge protection on new installations.
Can I fit this before an EV charger board?
Yes – it’s commonly installed as the fused incomer for EV-ready consumer units, giving both fault and surge protection upstream of the charger.
Do I still need a separate isolator?
No – the 100 A main switch provides full double-pole isolation. A separate isolator is optional, not essential.
- Model: WFMS100/3FSP
- Main Switch Rating: 100 A Double Pole (AC-22 A duty)
- Fuse Holder Type: 22 × 58 cartridge holder
- Fuses Supplied: 63 A, 80 A & 100 A (1 set per phase)
- SPD Type: Type 2, 40 kA 8/20 µs discharge current
- Response Time: < 25 ns
- Enclosure: Metal-clad surface mount, powder-coated steel
- Dimensions (W × H × D): 160 × 240 × 112 mm
- Ingress Protection: IP40 (indoor use)
- Voltage Rating: 230 V AC / 50 Hz
- Standards: BS EN 60947-3 / BS EN 61643-11 / BS 7671 Amd 2
Supplied pre-assembled with fuses and SPD fitted. Confirm correct fuse size before energising and verify the SPD status indicator after connection. Ensure the earth path to the SPD is as short as possible (< 0.5 m) for optimal protection.
- Mount on a non-combustible surface close to the meter or CU
- Bond enclosure and lid — check continuity < 0.05 Ω
- Keep SPD earth conductor direct to main earth bar
- Test SPD discharge and fuse continuity on commissioning
- Replace SPD cartridge if status window shows red
