After metering the voltage, we found that the current entering the house is about 184 and not 220V. The reason why our voltage stabiliser is popping is we are using a 250W 24V bulb and this would require a much more powerful unit. We grounded the connection but this made no difference as far as the humming. We also replaced the suspicious cable. No improvement.

My question is: what is the minimum bulb that can be used with this enlarger? 50 / 100W? The idea is, by lowering the wattage of the bulb, we can make it work with the voltage stabiliser (600W) -- anyone handy with calculations and can tell me the max lamp power for use with this stabiliser.

Any input is greatly appreciated.