A heating element or internal wiring sample of at least 150 mm in length is placed on a grid inclined at 45°. The grid is made up of parallel wires of 0.6 mm diameter spaced 20 mm apart. The sample is placed perpendicular to the horizontal wires and centered between the wires. A second grid of similar size is placed on the sample so that the horizontal wires are offset 10 mm from the horizontal wires of the first grid. The two grids are parallel to the sample and aligned with each other.
A heating element or internal wiring sample of at least 150 mm in length is placed on a grid inclined at 45°. The grid is made up of parallel wires of 0.6 mm diameter spaced 20 mm apart. The sample is placed perpendicular to the horizontal wires and centered between the wires. A second grid of similar size is placed on the sample so that the horizontal wires are offset 10 mm from the horizontal wires of the first grid. The two grids are parallel to the sample and aligned with each other.