Alternating electric current flow through a lamp fixture (L) of a maximum power rating is reduced without being terminated should a lamp be used in the fixture of a power rating that exceeds the fixture's maximum power rating. This is done using a thermally responsive switch (B) connected in series with a resistor (S) of relatively low resistance and in parallel with a resistor (P) of relatively high resistance, the switch and resistors being thermally connected, and by simultaneously passing alternating current to the fixture through an auxiliary line which has a diode (D1) that substantially halves current flow through the auxiliary line.