Memshield 2 – These are also a commercial breaker and come in types B,C & D. These also will fit into all Memera 2000 range boards. Bill Switchgear was probably one the oldest British electrical brands and was especially known for bigger switching devices like triple pole fuse switches and switch fuses and LV panelboards. The company was aquired by Delta in 1973 who also owned another well known brand, MEM.

Loadcentre – This was a new range introduced by Schneider but using the brand name of Square D. This is more of a commercial range with types B,C & D available (B type only in single pole). They have a breaking capacity of 10kA and. Later versions were branded as Schneider but are identical to the Square D. These will also fit the Qwikline II boards. The Wylex fuse box can be converted to miniature circuit breakers (MCB) it needs power off as to change over it exposes the live bus bars and the units are colour coded white = 6A, Blue = 16A, Yellow = 20A and Red = 32A so it is replace colour for colour. Initially the range was made to BS3871 standards so Types 2 & 3 were available from 6A up to 63A in single and triple pole. RCBO's were also available but they were initially referred to as MCB/RCD units as the term RCBO was not really established as yet. Memera 2000AD – These have a narrow terminal and only fit boards specifically marked Memera 2000AD. They won't fit in older boards. Delta decided to keep the brands MEM and Bill separate until 1998 when they finally phased out the Bill brand. What most people don't realise is that all the products that were manufactured were identical in both brands. Delta manufactured the products and either labelled them MEM or Bill.

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You can also buy MCB's pre-fitted with a pod in both the Memshield 2 and Memera 2000 ranges. These are usually just the 30mA size but field fit versions are availble is the following sizes: MEM first started manufacturing circuit breakers in 1965 and were one of the UK's biggest names in circuit protection. Now they go under the trade name of Eaton but still use the MEM name on some products. The Polestar range of breakers was unique because they had a higher than usual fault rating of 16kA where standard breakers at the time were 6kA and 9kA. What this meant was that Polestar could be used in areas where a high kA was required without having to use Moulded Case Breakers (MCCB's) or HRC fuse carriers. Crabtree Polestar breakers are also unique in that they are much wider (25mm) than a standard mcb (18mm). This extra width was needed for the bigger arc splitter to allow for a higher kA rating. In theroy you should test the loop impedance before changing. A 30A fuse will after many hours blow with 32A and in seconds with 100A and there is a curve linking the two. However with a 32A MCB there are two devices built into one. The thermal part works similar to a fuse but is slower than a fuse at high current so there is also a magnetic part which with the B rated MCB will trip between 3 and 5 times the thermal part so looking at 160A to trip it. To ensure a short circuit will trip the magnetic part we have to measure what the prospective fault current will be. Since ohms law comes in here we can actually measure the impedance (AC resistance) and that for a B32 should be 1.37Ω which allows for the volt drop of 5%.

Memera 2000 – There are several different styles of MCB's in this range but all will fit any Memera 2000 board.

This illustration shows the metal type Wylex consumer unit with the cover/frame in place. Perhaps the visible busbar that I referred to before is the neutral one visible if the frame is removed, near to the main switch.