The answer to 'my lighting installation won't turn on' is that there could be several common causes, such as a tripped circuit breaker, a loose connection, or a problem with the light fixture itself. Symptoms may include the lights not turning on at all or flickering/dimming unexpectedly. Solutions can range from resetting the circuit breaker to checking the wiring or replacing the fixture.
For simple issues, you may be able to troubleshoot and fix the problem yourself. However, for more complex electrical work, it's best to call a licensed electrician to ensure safety and proper installation. Attempting DIY electrical repairs without the right knowledge and tools can be dangerous and may even cause further damage.