Express each of these ideas as a compound.
1. a board consisting of a number of panels
2. material that does not allow water to get into it
3. material that doesn't allow rain to get into it
4. a board consisting of a number of electrical switches
5. conductors which are perfect, conducting a current without a battery
6. material that will not be damaged in an explosion
7. current which is greater than the load for which the system or mechanism was intended
8. material that does not allow dust to get into it