my $to_split = 'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z';

my @ra = split m{ (?: \',\' [^\',\']+){50} \K \',\' }xms, $to_split ;  

foreach my $piece(@ra){
print "\n\n" . $piece . "\n\n";
}