Opponents of proposals for more than 100 electricity pylons across mid Wales have pledged to hold “large and noisy” protests at meetings on the issue.
National Grid says the pylons in a corridor along the Vyrnwy Valley and parts of Shropshire are needed along with an electricity substation.
It is holding a series of information days, with the next at Cefn Coch, Powys, near the proposed substation.
Montgomeryshire Against Pylons says people should “ask awkward questions”.
An email from the campaign group tells supporters: “This week is incredibly busy for all of us.
“National Grid has booked a number of information days in community halls in our area and we are planning noisy and large protests outside the community halls.”
Cefn Coch is the energy giant’s preferred site for the proposed substation, which would cover 19 acres (7.6ha).
The firm has said it is trying to strike a “difficult balance” with its plans and said it “completely understood” opposition to the proposals.
But, National Grid has said, it was obliged to link up wind farms in mid Wales so the energy they produce can be put on to the grid in Shropshire.
It says the current infrastructure in mid Wales is not up to the job.
Opponents say the “hub” site and the pylons will disfigure the countryside.
The planning application for the substation will be submitted next year, and 2015 is the earliest start of any construction work, if permission is granted.