As I understand it the overriding issue is one of safety. If the umpires consider the conditions to be unsafe then the come off (and take a reading at that point), if they think it is OK they stay on.Many congratulations to the west indies yesterday.
I am all for allowing a game to continue in poor light, but can,t help thinking that if yesterday had been day 2 of the test they would have abandoned play with an hour to go.
If conditions were suitable for play yesterday then the same conditions on other occasions should also been deemed fit for play no matter what the match situation is at that time.
So has a precedent now been set that bad light is never an issue when the lights are on no matter what coloured ball is being used?
Where floodlights are being used, there seems to be this secondary question - are the floodlights taking over from the natural light. If the answer is yes then the advice seems to be that they come off - regardless of whether there is an overriding safety issue.
My understanding is that that playing conditions were not unsafe but that this odd rule about floodlights could have been invoked but thankfully was not.
Seems sensible to me.