Network solids and many covalent compounds have nonpolar bonds.
A covalent bond is nonpolar if the electronegativity difference between the atoms is less than 0.4. Thus, a C-H bond is nonpolar.
The most common covalent compounds with nonpolar bonds are hydrocarbons. These include methane CH₄, ethane C₂H₅, propane C₃H₈, etc.
The only intermolecular forces between hydrocarbons are weak London dispersion forces.
Hydrocarbons have low melting points and boiling points. Many are gases at room temperature. They do not conduct electricity as solids or liquids or when dissolved. They dissolve in other nonpolar liquids.
In network solids, covalent bonds connect the atoms in a continuous 3-D network. Diamond and graphite are network solids.
In diamond, the carbon atoms joined in a giant form 3-dimensional network. In graphite,the carbon atoms are arranged in layers.
Network solids are usually hard. They have high melting and boiling points and are non-conductors of electricity.