The tourists are currently 172-7 in their second innings, which gives them a lead of 331 runs heading into the final day at Old Trafford.
The decision whether to leave the field for bad light used to be one taken by the batsmen, and captain Michael Clarke - at the crease on 30 - seemed happy to carry on.
However, a change of the rules back in 2010 means that the umpires have to abide by the preference of the fielding team and Alastair Cook, not wanting to bowl spin with the new ball, chose to head back to the pavilion.
"The playing conditions changed a few years ago so it's now our decision," Erasmus told Sky Sports News. "We try and communicate and let everybody know.
"For a while there England's fielders were asking about the light and the possibility when they bat. It was fine by then but it kept dropping, dropping, dropping.
"Eventually we told the captain to bowl spin which eventually he decided not to. That pushed our hand because it's a safety issue."
Clarke will resume tomorrow alongside Mitchell Starc (66).