This 40A B-curve circuit breaker (MCB) is mainly used to protect supply cables: for example, the cable from the main consumer unit to a sub-board in a garage, workshop or garden shed. Both poles are protected, so it can also be used in a 3×230 V network, where both conductors are phase conductors.
When do you choose a B40?
- a long supply cable to an outbuilding, where the short-circuit current at the far end remains low
- a heavy single-phase load without a high starting current
- an appliance for which the manufacturer specifies a B40
According to the table for homes in AREI (the Belgian electrical installation regulations), 40 A requires at least 6 mm²; over longer distances, electricians often choose 10 mm².
Why a B curve?
A B-curve MCB trips magnetically at 3 to 5 times the rated current, so at 40 A from 120 to 200 A. On a long cable, the short-circuit current at the far end is sometimes too low for a C-curve MCB, which only trips magnetically from 200 to 400 A; a B-curve MCB will still trip quickly in that case. Your electrician will verify this by calculation.
Benefits
- energy limiting class 3: low let-through energy in the event of a short circuit, which spares the cable and the upstream protection
- back-up fuse up to 80 A gG permitted
- twin terminals on both sides, for conductors up to 25 mm²
- IP20, IP40 with cover
Good to know
A sub-board must itself also comply with AREI, with its own MCBs and the required residual current protection. Leave this work to a qualified electrician. If you extend your installation, you must then have it inspected again by an approved inspection body.
| Product code | BM418240 (Schrack BMS4 B 40/2) |
|---|---|
| EAN | 9004840394375 |
| Rated current | 40 A |
| Tripping curve | B |
| Poles | 2P, both poles protected |
| Breaking capacity | 4.5 kA (EN 60898-1), 6 kA (EN 60947-2) |
| Rated voltage | 230/400 V AC, 50/60 Hz |
| Width | 2 modules (approx. 35 mm) |
| Terminal capacity | 1 to 25 mm² |
| Power loss | 7.5 W |
| Max. back-up fuse | 80 A gG |
| Degree of protection | IP20, IP40 with cover |
| Ambient temperature | -5 °C to +40 °C (calibrated at 30 °C) |
| Standards | EN 60898-1, EN 60947-2 |
| Reference | 9004840394375 |
| Category | Circuit breakers and RCDs |
| Merk | Schrack |
| Weight | 0.24 kg |
Shipping with GLS
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