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

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From Table B6 of the OSG, the maximum measured Z s value is1.75 Ω at an ambient temperature of 10 oC.

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.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. 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. However when I look at table 41.1 it is stating that if Uo is 240Vac the permissible disconnection time is only 0.2 seconds. Example of Resi9 and Eazy9 circuit breakers for residential applications Where should IEC 60898-1 certified CBs be used? Manufacturers warn against installing circuit- breakers of one manufacturer as replacements for cbs of another manufacturer, without the necessary verification of performance.

Where manufacturers’ values of Z s for MCBs are used, they will often recommend multiplying the measured value of Z s by a correction factor, to correct for ambient temperature. For example, Schneider, recommend using a factor of 0.8, So a barefoot victim gets exposed to about 120V, and maybe we can have an argument about reduced CPC in twin and earth. In many European countries there is no table, they only have the formula in their national standards. Note that BS7671:2018 clause 411.4.202 does state that the permissible Zs can be calculated and in my opinion it is the best method to ensure that we are not failing Zs values that are still low enough to achieve the required disconnect time. I will give you an example:IEC 60947-2 governs circuit breakers (CBs) for industrial applications. They protect electrical power distribution of up to 1000 volts a.c. and 1500 volts d.c. with an entire spectrum of rated currents from 0,5 to 6300A. Utilities and manufacturing facilities often use air circuit breakers (ACBs), molded case circuit breakers (MCCBs), and miniature circuit breakers (MCBs) No. Consequences can be serious if residential CBs are used instead of industrial ones. An MCB designed for indoor, pollution degree 2 conditions would be inadequate for harsh, outdoor applications that require pollution degree 3. The most suitable solution is for MCBs that are certified by both IEC standards since their performance meets requirements for use in residential installations and is high enough for use in industry and infrastructure applications. Due to the high level of protection performance of these CBs, they should be used at least for the incoming electrical switchboards in buildings applications. Appliance for MCB’s to standards in different applications of use

Table B6 of the OSG and Table A4 of GN 3 contain maximum Z s values for circuit-breakers based on the cross-sectional area (csa) of the protective conductor and at an assumed conductor temperature of 10°C. For example, the BS EN 60898-1 standard describes B, C and D operating curves with ratio to rated current. But the BS EN 60947-2 standard prescribes an instantaneous tripping release which may be provided with a plus or minus 20% tolerance and adjustable as illustrated in Fig. 1. For this reason, manufacturers provide additional curves K, Z and MA to the B, C and D curves. 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).

Where a more frequent switching is required, such as the switching on and off of banks of luminaires, the manufacturer’s instruction should be followed and preferably an alternative device should be selected.

That's quite a large difference and hence the reason why the national standards in other European countries do not include Zs tables, only the formula is provided.IEC 60898-1:2015 applies to a.c. air-break circuit-breakers for operation at 50 Hz, 60 Hz or 50/60 Hz, having a rated voltage not exceeding 440 V (between phases), a rated current not exceeding 125 A and a rated short-circuit capacity not exceeding 25 000 A. This second edition cancels and replaces the first edition published in 2002, Amendment 1:2002 and Amendment 2:2003. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: Or take the tripping characteristics: IEC 60898-1 clearly describes B, C, and D curves with ratio to rated current, while in IEC 60947-2 the instantaneous tripping release may be adjustable according to the need of the user, or pre-defined by the manufacturer, with ±20% tolerance. This is the reason why manufacturers additionally provide a wide scope of different curves: K, Z, MA. If it was a curve of disconnection times versus voltage in the regs and not a table no one would care, as 230V and 240v would have times very similar.