This is the second in the series of npower campaigns to feature the pair as the company looks to promote energy efficiency.
The 30-second TV ad wk during the Home Show on Channel 4 on Thursday and sees the duo attempt to insulate their loft using sheep.
McCann Erickson is handling the PR for npower on the campaign.
Kevin Peake, marketing director for npower, said: "We're hoping their [Wallace & Gromit's] positive appraoch to energy efficiency will help people see how simple it is to make small changes and a big difference to their energy bills."
Below is a special video showing some of the behind the scenes production on the new ad.