Defects in photovoltaic installations can include defects in connectors and junction boxes. The consequence of poor quality connectors is poor electrical contact, damage during installation or after exposure to the elements. Eventually, parts of the installation may burn out. Another cause of burnout is poor quality junction boxes with incorrectly installed bypass diodes. Junction boxes contain 'by-pass' diodes in their design, whose role is to cause current to flow outside the shaded cell. If they are not working properly they can overheat and then burn out.