Is there a reason why all conventional domestic electrical wiring fittings use exclusively slotted screw heads, rather than the much more practical Phillips or Pozidrive heads? Don't tell me that electricians can only carry one screwdriver?
I suspect terminal screws standardised on slotted as that was probably the only option available in the beginning (early 1900s?).
A few terminals tried using more "modern" recesses but often made a complete pig's ear of it - e.g. on MCBs where they tried to come up with a recess that would accept both pozi and slotted - but ended up with something that worked properly for neither an ended up selling special (+-) driver.
For normal tunnel terminals taking soft copper, there's no need for the higher torques that the cross recesses can provide - indeed it might even encourage over-tightening and damaged conductors. Similarly with faceplate screws too tight and things will crack or distort.
I suspect terminal screws standardised on slotted as that was probably the only option available in the beginning (early 1900s?).
A few terminals tried using more "modern" recesses but often made a complete pig's ear of it - e.g. on MCBs where they tried to come up with a recess that would accept both pozi and slotted - but ended up with something that worked properly for neither an ended up selling special (+-) driver.
For normal tunnel terminals taking soft copper, there's no need for the higher torques that the cross recesses can provide - indeed it might even encourage over-tightening and damaged conductors. Similarly with faceplate screws too tight and things will crack or distort.
