So, I just installed an electric water heater and I'm getting a light hum from the water heater and the breaker panel. It's also dimming some lights.. unevenly. It seems to be more noticeable when the hot water is cracked, but it's annoying, because I've checked everything so many times now. I've contacted the power company an an electrician to come out next week, but any other ideas?
200 AMP service.
Murray breaker box.
New Murray breakers (2 x double pole 40 AMP).
8 Guage Stranded Romex (40' run).
Rheem RTEX 18.
All connections good and tight.
Small 600sqft house, 2 people, not much load otherwise.
Cleaned bus bars.
Breakers not hot, not loose.
Set to 110 degrees.
I've tested breakers and power at the WH. Everything appears to be fine.. However, going back to the idea of the problem being apparent with lower water, I checked the heating elements and noticed that when the hot water is on low, one element is on. When it's medium, the second element engages at 120, and at full the second element is at 240. Could the on/off, uneven volts be part of the problem? Is there a way to remedy this?
Any ideas?
Best Answer
18KW is a 75 amp load at 240volts , which is a HUGE addition in draw for a very small house. For comparison, if you replaced a tank type water heater they typically have 2 4,500 watt elements but only one is on at a time for a current draw of just under 20 amps. You say you ran 8 gauge Romex, I assume that's 2 runs one for each 240volt breaker.
LEDs esp. with dimmers can be very sensitive to voltage changes. I have some in my home, on the same dimmer that dim at slightly different rates even though they are on the same circuit/dimmer.
Last, I agree with Mazura, your power drop from the POCO may have been adequate before, but now, with that much larger load, isn't anymore.