Solid ionic compounds do not conduct electricity because the ions are held firmly in place. The ions cannot move to conduct the electric current . But when an ionic compound melts, the charged ions are free to move.

Does a lattice conduct electricity?

In the solid phase the ionic lattice has no mobile ions as all the ions are fixed in place. However when dissolved in a solution or in the molten phase, the ionic lattice breaks down allowing the ions to move and carry charge. This allows the conduction of electricity.

Do ionic lattices conduct electricity when solid?

Ionic substances will not conduct electricity as solids. This is due to the fact that ions are not free to move in a solid as they are arranged in an ionic lattice.