ECN Forum Forums General Topics of the Trade General Discussion Area Industrial 56" ceiling fan troubleshoot

The speed control works by chopping up the AC waveform, such that it is no longer a nice clean sine wave. Unless you use a "True RMS" multimeter, non-sinusoidal waveforms cause very screwy AC voltage readings in most cases.

Recheck the reading using a good quality TRMS meter, such as a Fluke 87.