MK 6 AMP TYPE 2 M6 MCB CIRCUIT BREAKER 240V LN 5906 BS 3871

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Now for something nifty: the _instantaneous_ voltages between points must always add up. If I measure 5V (DC) from A to B, and 6V (DC) from B to C then I will get 11V from A to B. If I measure 5V from X to Y and 6V from X to Z, then I will measure 1V from Y to Z. Finally , if I measure 5V from A to B, I will measure -5V from B to A. But this is all DC, or instantaneous voltage. When carrying out an earth loop impedance test you are carrying out the test under normal conditions, so to take into account of the rise in cable temperature under fault conditions we need to apply the 0.8 correction factor to the maximum Zs value, therefore 1.37 * 0.8 = 1.096 (rounded to 1.1) which you then compare to your test results.

Make a graph of the difference between A and W, and you will find out that it is a sine wave with low amplitude. In fact, it is a law of mathematics that the sum or difference of two sine waves of the same frequency (but possibly different amplitudes or phases) is another sine wave of the same frequency, again with different frequency or phase.

So the Zs calculation formula for a 0.1s to 5s disconnection time for a BS EN 60898 MCB or BS 3871 to calculate the maximum Zs would be: Step 2 remember that for AC circuits the voltage is a constantly changing value, and when we give a single number, it is a form of average voltage, called the RMS voltage. The RMS voltage of an AC waveform corresponds to the DC voltage which would deliver the same power to a resistive load. If you take AC at 480V RMS and apply it to a 480 ohm resistor, the average power delivered to that resistor would be 480W. If you take DC at 480V and apply it to a 480 ohm resistor, the power delivered to that resistor would be 480W. BS 3871 circuit breakers were also manufactured as Type 4. Generic data cannot be used for Type 4 circuit breakers and the manufacturer’s data must be used to calculate maximum values of earth loop impedance. The more common forms of Type 4 are listed in the following tables, together with their maximum values of Z s, for 0.4s and 5s disconnection times. FEDERAL If you are looking for reason to keep the existing despite the mains upgrade, then you will need more data, but don't be surprised if it doesn't help much - do you know for example if it was compliant before the upgrade took place (ie at the previous fault level) - have you tried a random MCB is say Amtech (or data from a different supplier)

is the old British standard for MCB's so BS 3871 does not tell anyone what type of MCB it is. I looked at http://www.beamainstallation.org.uk/assets/pdfs/CircuitBreaker.pdf which explains how the standards evolved. WHY used square root 3 in calculation –> this is the answer,please read discussion on this forum : http://www.electrical-contractor.net/forums/ubbthreads.php/topics/129279/1_732_square_root_of_3_where_d.html Additionally, any commercial, industrial, or public building that is supplied by overhead lines requires surge protection – so the majority of buildings will require surge protection. Residential properties will depend on use and occupancy levels. Knowing the right type of device to install is essential to protect equipment in all types of buildings, as is reflected in the evolving guidance.

Types of Surge Protection

The 100% values should be recorded as the maximum permitted Zs value on the electrical test certificate and the temperature adjusted 80% values are used to compare against the actual readings obtained when testing the circuit. 60947-2 Max Zs Values

The Dorman Smith Loadmaster was very common years ago and because not a din rail mount very hard to replace without whole enclosure replacement but I seem to remember there was only a thermal trip in them and not a magnetic type as well so they would not have a number or letter just a current rating. A Type 1 SPD is designed to provide protection against surges caused by direct lightning strikes. These often feature spark gap technology, which can handle very high voltages by creating a short to ground when a level of current is reached. Type 2so that implies with that breaker 2.5mm is not OK, but you are comfortably OK with all cables of 4mmsq up and larger. The person introducing a modification/alteration becomes the original manufacturer with the corresponding obligations for that assembly.

A Type 2 device offers protection against over-voltages from switching and indirect lightning strikes. This type more commonly uses a metal oxide varistor (MOV) to divert the current away. Type 3The Cmin factor is applied to the voltage to earth (Uo), so if the voltage is 230 the calculation would be 230×0.95 = 218.5 volts. The last bit is to ask ‘how do I calculate the voltage difference between two phases with some other phase angle?’ Clearly this is some function of the amplitude of the phases, and also a function of the phase angle between them. Simplify the question by stating that both phase A and phase W have the same phase to neutral RMS voltage V. Call the phase angle between these two phases T. The voltage between the phases is then given by V * 2 * sin(T/2). So for the 180 degree phase difference we get V * 2 * sin(180/2) = V *2