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What is DC on the powerline?
by Nyal MellorApril 08, 2013
Half wave rectification from devices within the home such as older hair dryers causes DC offset. It can also be caused by industrial devices outside the home that load the power line unevenly.
The typical observed effect is transformer buzzing and 'growling' due to saturation of the magnetic core. Larger transformers, often found in amplifiers, are more susceptible than smaller.