crab tree cu with merlin breaker?

[12345aob]

I friend of mine just phoned me to tell me that his lighting in his shop keeps tripping, after a few qustions i concluded he had a faulty fitting but in my questioning i asked him to look at his cu and he told me that his last breaker in his crabtree unit was a merlin one - i was just wondering if crabtree and merlin are compatible as it sounds a little strange to have two different types of breakers?

 

[tony.towa]

Realistically it's not a case of compatability.
Miniature circuit breakers, as manufactured by reputable companies comply to DIN specifications and BSEN60898, the latter giving the functional requirements.
In order to comply with the DIN spec the front escutchion on the breaker and the rear shaping have to comply to specific sizing, the locations of the connection terminals have to be within specis areas but the exact positioning, within these areas, is down to the manufacturer, hence some mcbs will fit in other manufacturers boards and some will not (sometimes they stick out of the cu slightly more).
Installation of an alternative manufacturers mcb should not generally be done (unless as an immediate and temporary solution or when the original or subsequent mcb is no longer available) as any form of warranty or product guarantee is negated and total liability for any problem becomes the sole responsibility of the person fitting the device.