Bruce wrote...
In the following formaula i am essentually summing a range if another
range
in the same row = zero

=IF(SUM(CT2:CW2)=0,SUM(CW2:DH2),0)
....
How do I modify the above as an array formula so that it inspect and
total
for rows 2 to 300.
....

You want the row-wise sums of CT:CW and CW:DH. Use MMULT.

=SUMPRODUCT(--(MMULT(CT2:CW300,{1;1;1;1})=0),
MMULT(CW2:DH2,{1;1;1;1;1;1;1;1;1;1;1;1}))