Posted 20 hours ago

Square D KQ B 32 AMP MCB 240 v BS60898 10B132 A 10Ka CIRCUIT BREAKER

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About this deal

Circuit-breakers are primary circuit protective devices. They are not intended for frequent switching of loads. Infrequent switching of cbs on load is admissible for the purposes of isolation or emergency switching.

Manufacturers warn against installing circuit- breakers of one manufacturer as replacements for cbs of another manufacturer, without the necessary verification of performance. Two requirements that ensure reliability of circuit- breakers are the ultimate breaking capacity (I cu) and service breaking capacity (I cs).Assemblies such as distribution boards are validated with specific circuit-breakers installed and these cbs are usually from the same manufacturer as the distribution board. Where cbs made by a different manufacturer are to be installed, verification will have to be undertaken by the manufacturer of the distribution board to BS EN 61439-2 or BS EN 61439-3. Fitting unverified devices will invalidate any verification and the warranty.

Circuit-breakers to BS EN 60898-1 can also comply with BS EN 60947-2 but the short-circuit breaking capacity of each may be different. Some manufacturers state that their cbs with a short-circuit capacity of say, 10 kA comply with BS EN 60898-1 and the same cb with a short-circuit capacity of 15 kA complies with BS EN 60947-2. The table is based on nominal rather than actual voltage - 230V nominal is usually taken to be anything within the -6% to +10% range - i.e. between 216.2V and 253V. It's very common for DNOs to have far above 230V at their transformers to compensate for voltage drop in the distribution system - typically a 433/250V. So as long as your supply doesn't go above 253V (during times of low load say) I'd say it's acceptable to use the 230V nominal column (e.g. 0.4s for TN small final circuits). It is convenient when the performance of a cb meets the requirements of both standards and is therefore suitable for residential, industrial and commercial installations.

Can IEC 60898-1 be used instead of IEC 60947-2?

Yes. The rated voltage currently required in industrial use CBs is 400 V, 440 V, 690 volts, or higher values up to 1000 V. Compare those numbers to the usual value 230V/400 V for residential MCBs. Reference ambient temperature is 30°C for households. The same goes for impulse withstand voltage (Uimp), IEC 60898-1 requires 4kV, in line with the use for final circuits. Whereas for industrial circuit breakers, the usual values of Uimp are 6 or 8kV, in line with the position of the circuit breaker at the origin of the installation.

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