Any one  CE marked compliant LED driver at least working properly should not allow more that a fraction of a mA from it's Live/neutral input to come out out through the LED side low voltage terminals,  and that is the maximum that one may expect to get on to the mounting frame.

But a ceiling full of them may well add up to a lethal shock.

Most of us start to feel tingles around about 0;1 to 0,5 mA and it gets very painful and the flinch reflex becomes expected, as we increase the current  up through the whole nos of mA. By 30mA you need to be disconnected pretty pronto to save you - hence RCDs - hoping to be  thrown clear by muscle contractions is not reliable enough....

Exact sensitivities vary quite a bit from person to person, and with other factors such as skin dryness/humidity , area of skin in contact etc,  so treat the figures above as a very rough guide. (in most years there are a few more electrocutions in summer when folk are more likely to have bare arms or even bare feet, and are likely to sweat more.)

As others have said above, the problem is that within the LED driver, there are transformer windings, which as well as being windings are made of metal and spaced by insulation, so also act as the two 'plates' of a rather oddly shaped adventitious capacitor straddling between incoming mains and the ELV secondary side - for a switch mode supply this capacitance  is typically some hundreds of pF to nana-farads, depending on the detail of transformer construction - not enough current will pass to do damage, but certainly enough to be seen on a modern digital meter, and a few such 'capacitors'  in parallel between the supply and metal ceiling grids, so the currents add,  could become  dangerous..

Earthing the ceiling grid will ensure that part at least is held near 0V,  so that the effects of many sensibly spaced lamps cannot add up. but on the other hand this makes the effect of putting yourself  between the grid and  any one light more obvious.

Mike

Any one  CE marked compliant LED driver at least working properly should not allow more that a fraction of a mA from it's Live/neutral input to come out out through the LED side low voltage terminals,  and that is the maximum that one may expect to get on to the mounting frame.

But a ceiling full of them may well add up to a lethal shock.

Most of us start to feel tingles around about 0;1 to 0,5 mA and it gets very painful and the flinch reflex becomes expected, as we increase the current  up through the whole nos of mA. By 30mA you need to be disconnected pretty pronto to save you - hence RCDs - hoping to be  thrown clear by muscle contractions is not reliable enough....

Exact sensitivities vary quite a bit from person to person, and with other factors such as skin dryness/humidity , area of skin in contact etc,  so treat the figures above as a very rough guide. (in most years there are a few more electrocutions in summer when folk are more likely to have bare arms or even bare feet, and are likely to sweat more.)

As others have said above, the problem is that within the LED driver, there are transformer windings, which as well as being windings are made of metal and spaced by insulation, so also act as the two 'plates' of a rather oddly shaped adventitious capacitor straddling between incoming mains and the ELV secondary side - for a switch mode supply this capacitance  is typically some hundreds of pF to nana-farads, depending on the detail of transformer construction - not enough current will pass to do damage, but certainly enough to be seen on a modern digital meter, and a few such 'capacitors'  in parallel between the supply and metal ceiling grids, so the currents add,  could become  dangerous..

Earthing the ceiling grid will ensure that part at least is held near 0V,  so that the effects of many sensibly spaced lamps cannot add up. but on the other hand this makes the effect of putting yourself  between the grid and  any one light more obvious.

Mike