One lamp or several rooms?
Note whether the flicker affects one fitting, a group controlled by a dimmer or lights in several rooms. Record whether it began after a lamp change or occurs when other equipment starts. Do not keep reproducing a fault if there are any warning signs.
Compatibility is one possibility
A lamp and dimmer may not be suitable together, but flickering can have other causes. Do not assume that a new bulb or switch is the answer before assessment. A buzzing, hot, damaged or unusually smelling accessory should be left unused and checked.
Explain the desired outcome
For a repair, provide the fitting and control details if available without opening anything. For a lighting upgrade, discuss the desired brightness and control options before products are purchased. Ask for the proposed combination and installation to be checked as a system.
Further information
Electrical Safety First: warning signs · E-REDES: faults and network information · Portugal emergency contacts
General safety information, not a diagnosis or a guide to electrical work. UK-specific installation rules are not presented as Portuguese requirements.