Time Delayed RCD 125A Metal Fuse Switch with 3 × Fuses (WFMSRT00-3F)
18th Ed. Compliant
2-Year Warranty
UK Stock
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The WFMSRT00-3F is a 125 A metal fuse switch assembly that integrates a 4-pole time-delayed RCD and three 22 × 58 mm cartridge fuses, offering complete fused isolation, residual current protection, and discrimination for sub-main circuits. Built for demanding environments, it ensures selective fault clearance and surge resilience in accordance...
The WFMSRT00-3F is a 125 A metal fuse switch assembly that integrates a 4-pole time-delayed RCD and three 22 × 58 mm cartridge fuses, offering complete fused isolation, residual current protection, and discrimination for sub-main circuits. Built for demanding environments, it ensures selective fault clearance and surge resilience in accordance with BS 7671 Regulation 536.4.1.4.
Installer Tip: Use the WFMSRT00-3F on sub-mains feeding distribution boards or critical equipment. The time-delayed (S-type) RCD prevents nuisance tripping by ensuring selectivity with downstream RCBOs — essential in tiered RCD setups under Reg 536.3.3.
- 125 A 4-pole fused isolator with integrated time-delayed RCD
- Supplied with 3 cartridge fuses (63 A / 80 A / 100 A) for load-specific selection
- S-type (selective) RCD – designed to trip after a set delay to maintain discrimination
- Heavy-duty metal enclosure with secure locking lid and pre-fitted knockouts
- Complies with BS EN 60947-3 & BS EN 61008-1
- Ideal for three-phase boards, heat pump circuits, or EV infrastructure
| Model | Main Switch | Fuses | Extras | Common Use |
|---|---|---|---|---|
| WFMS100 | 100 A 2 Pole | 1 × Fuseholder | – | Domestic isolation |
| WFMS100/3F | 100 A 2 Pole | 3 × Fuses | – | Domestic incomer |
| WFMS100/3FSP | 100 A 2 Pole | 3 × Fuses | Type 2 SPD | Surge-protected incomer |
| WFMS/3P | 125 A 4 Pole | 3 × Fuses | – | Three-phase isolation |
| WFMSRT00-3F | 125 A 4 Pole | 3 × Fuses | Time-Delayed RCD | Sub-main or critical load protection |
Combining high fault withstand capability with time-delayed residual protection, the WFMSRT00-3F is engineered for electricians who need a single, compliant enclosure to handle both isolation and selective RCD control at the distribution level.
What does “time-delayed” mean?
Time-delayed (S-type) RCDs introduce a short delay before tripping, ensuring they operate selectively — disconnecting only when a fault is not cleared by downstream protection devices.
Where should the WFMSRT00-3F be installed?
Typically used on sub-main circuits between the main incomer and distribution boards, or for critical systems where nuisance tripping must be avoided.
Can I use it in an EV installation?
Yes – it’s ideal for EV distribution panels where discrimination with 30 mA RCBOs is required.
Is the RCD adjustable?
No – the delay time and sensitivity are fixed to provide standard selectivity performance in line with BS 7671 Reg 536.4.1.4.
Are replacement RCD modules available?
Yes – replacement S-type 4-pole RCDs can be supplied separately. Contact our sales team for part compatibility.
- Model: WFMSRT00-3F
- Main Switch Rating: 125 A 4 Pole (AC-22 A duty)
- Fuse Holder Type: 3 × 22 × 58 cartridge holders
- Fuses Supplied: 63 A, 80 A & 100 A
- RCD Type: S-type (time-delayed) – 100 mA or 300 mA
- Trip Delay: 130 – 500 ms (selective operation)
- Enclosure: Metal-clad, surface mount, powder-coated steel
- Dimensions (W × H × D): 130 × 238 × 87 mm
- Ingress Protection: IP40 (indoor use)
- Voltage Rating: 400 V AC / 50 Hz
- Compliance: BS EN 60947-3 / BS EN 61008-1 / BS 7671 Amd 2
Supplied pre-wired and fitted with an S-type (time-delayed) RCD. Always test the RCD and confirm tripping times before energising. Ensure fuse ratings are matched to downstream cable size and fault current calculations.
- Mount securely to a non-combustible surface
- Verify RCD operation using ramp and trip-time tests (BS EN 61008-1)
- Maintain earth and neutral continuity through the 4-pole switch
- Keep SPD or RCD earth leads short and direct
- Label enclosure clearly with RCD delay time and fuse ratings
