Only 5.3 overs were bowled on Friday, after an initial delay of several hours, following South Africa captain AB de Villiers's decision to field first.
England were 37 for no wicket when fresh rain finished off the match with opener Bell 26 not out off 18 balls, including two sixes and two fours.
Alastair Cook, England's one-day captain, was 10 not out. Fast bowler Morne Morkel's three overs cost 19 runs and left-arm paceman Lonwabo Tsotsobe conceded 18 in 2.3.
Just days after South Africa dethroned England as the world's top-ranked Test side, following a 51-run win at Lord's, they arrived in Cardiff knowing a 2-2 draw or any kind of series victory in this five-match contest would see them replace their hosts at the summit of the one-day standings too.
No sooner had Morkel opened proceedings with a legside wide, then the umpires – in a match already reduced to 23 overs per side – took the players off to a chorus of boos from a frustrated crowd before re-emerging minutes later.
When play resumed, left-hander Cook struck Tsotsobe through the covers for four. Bell then produced a couple of extraordinary shots, going down the pitch to loft Morkel for six over the legside and, three balls later, advancing to drive him for another superb six over mid-off.
In all 16 runs came off the fifth over. There was just time for Bell to flick another boundary, off Tsotsobe, before more rain saw the match, in which South Africa batsman Dean Elgar was making his debut, abandoned. The series continues at Southampton on Tuesday. – AFP