Lights flickering or dimming when using the Brother machine can be explained by the following information:
The operating current for the Brother machine while printing is approximately 6.1 amps. When the machine is warming up it may peak at approximately 9.0 amps. This peak enables the machine to print the first page quicker. Sometimes this warm-up peaking will cause lights to flicker as the power is drawn. You may experience similar light flickering if you plugged in a hair dryer or similar appliance into the same electrical outlet.
Most household circuits are rated at either 15 or 20 amps. If you have a question about the maximum amperage that your electrical circuit can handle you should consult a qualified electrician. The Brother machine has been approved by Underwriter's Laboratory (UL).