I was at a job today and the customer complained of their LED lights flickering when the dishwasher was running. After running the washer for a few min there was a drastic drop in all of the LED's in the house as well as some flickering. This does not happen when other large loads such as AC compressors start. I checked the connections all the way back to the main and the main service itself everything appeared to be ok. Anyone have any thoughts on this?
1. Did you try measuring the voltages at the boxes feeding the LEDs?
2. Are the LEDs on dimmers? They could be sensitive to transients on the power lines.
3. Is the dishwasher fed from an electric hot water heater? The voltage drop you are seeing could result from the heavy draw of an electric water heater rather than the dishwasher itself.
4. Some dishwashers have an electric hot water heating element which could also be a heavy power draw.
5. Does the dimming and flickering stop the moment you turn the dishwasher off?
6. Did you check neutral connections as well as hot wires?
7. Is the dishwasher hard wired or plugged into an outlet under the sink? If the latter, you can put a clamp-on ammeter on it (using a splitter adapter) or run it temporarily on an extension cord from another source.