> It contains a formula:

=IF(G12="","",IF(G12="FIXED POWER",SUM(((T12*C12*K12)/1000)+U12),IF(G12="LIGHTING",SUM(((T12*C12*K12)/1000)+U12),IF(G12="RING MAIN",SUM(((T12*C12*K12)/4000)+U12),"Cct Type!"))))

Although unrelated to your question, how about using this shorter formula instead:

=IF(G12="","",IF(OR(G12={"FIXED POWER","LIGHTING"}),((T12*C12*K12)/1000)+U12,IF(G12="RING MAIN",((T12*C12*K12)/4000)+U12,"Cct Type!")))

Aladin