10 March 2012
You will deduct TDS on installation charges as per limit prescribed but so for as WCT TDS it will not come under the purview of works contract. It is a case of purchase and installation is a integral part of purchase. However since he is raising separate bill of installation you have to deduct TDS
11 March 2012
Purchase & installation are two separate contracts- then On purchase of DG set, CST charged will not be eligible for input. Installation is a separate contract which will be purely labor contract, this will not attract WCT TDS. If it is inclusive of material required for installation and gross contract value exceeds limit of Rs. 500000/- and if you are notified dealer then TDS @2% or 4% is to be done under WCT.
TDS under I Tax is to be done if gross contract value for installation exceeds the prescribed limit for TDS.