Watts Calculation Too High Aeon Labs HEM

Hello! I have been trying to configure this darn thing for three days now. I managed to get the reporting working properly, but I have never been able to get the Watts calculation to work. The only way I seem to be able to bring it even remotely in range is by setting Config Variable 1 (Volts) to the value of 1. Yes, just 1. I believe I’m supposed to be using either 120 or 220 (US or EU) but with my value (120 for US) I get a Watts reading sometimes up to 400,000 combined (Clamp 1 and 2 combined). So I’m missing something, but can’t figure out what it is.

Tonight I tried an experiment by putting a single lamp on a split lamp cord. I put one clamp around the hot side of the cord to measure current. At the normal variable 1 setting of 120, my watts read over 17,000 on the clamp. When I set variable 1 to just 1, I still get 153 watts (it’s a 75 watt bulb).

Here is my config:
Firmware: 3.67 (updated today)

1: 1 (Should be 120 but 1 gets me closest to actual watts)
3: 0
101: 6924
103: 1B00 (6912)
111: 10
113: 10

Thanks for the help


First of all, I learned from other forum topics that I was using the wrong settings. I am now using the following:
3 = 0 (turn off the delta function)
101 = 770 (report watts for clamps 1&2 and multi sensor watts (total watts))
103 = 6152 (report kWh for clamps 1&2 and total kWh)
111 = 10 (report at 10 second interval for the watts data in 101)
113 = 60 (report at 60 second interval for the kWh data in 103)

Then I set variable 1 back to 120. Sure enough, Watts spiked back up to over 400k per clamp, and at one point over 1 million for the total.

Then I added variable 255 (reset HEM to default configuration), 4 byte dec, value “0”. I had to configure the node twice, and it always returned an error. But low and behold, the watts magically started showing reasonable figures. After 24 hours, I am now confident that my power data is reading/reporting properly.

Other notes:
Variable 255 is a reset to factory default configuration (not a recalibration of the HEM), but it did not wipe out my other configurations in 101-103. Once the meter was reading properly, I deleted variable 255.

Thanks for the tip, setting 255 to 0 fixed mine, also required 2 configs for it to start sending the right watts.

However I’m still stuck with the ludicrous KWH reading of like 130k, is there a way to reset this counters for the 3 devices?

Oh, also, is there a reason you disabled the delta function? seems like a pretty cool feature or did you notice it transmitting too much junk?


Do a search on the forum to reset the hem. I made a scene when activated resets the hem. Works nice.

Just create a new scene and paste this into the LUUP tab. Then whenever you want to reset the KWH just run this scene:
Change 77 to your HEM’s device number below

local meterID = 77
local kwh = luup.variable_get(“urn:micasaverde-com:serviceId:EnergyMetering1”, “KWH”, meterID)

luup.call_action(“urn:micasaverde-com:serviceId:EnergyMetering1”, “ResetKWH”, {}, meterID)

Can the HEM be used for watts info for 2 branch circuits? I have a couple of sump pumps for my swimming pool that I would like to monitor. They are hard wired, so I cannot use the Smart Switch and was hoping the HEM could work. I only will need watts reporting to verify the pumps are working correctly and will use PLEG for notification if it has been several days since the pump has run (ie. no wattage reporting)

Should be no problem, as long as you can get the two current transformers clamped around the two hot wires feeding the pumps. I do something similar monitoring two DC to AC power inverter outputs with a HEM gen 1.

Yes it will work fine for this, actually it’s exactly why I bought a 2nd HEM unit. I’m using it for my Furnace and Fridge during the winter for testing.

I got the HEM installed and the clamps are working great. Also using PLEG to do some logic with the wattage reported from the clamps. I picked up the GEN 1 on Amazon for $29.99

Sorry to bring up an old post, but I wanted to share what I found out.

I too had the problem with very high wattage readings. I believe I figured out why it was happening. I installed my HEM at the main box on the other side of the house. When it came time to pair, I brought the box back to my desk and connected it to a power adapter. I successfully paired the box and it started reading wattage readings, I thought it was weird but when I put the box back at the panel, the readings were out of range. After enlisting a fiend to hit the pair button at the panel when the clamps were connected everything started working.

I believe that when the device is paired, it is reset and the values for the watt readings are set. I tried the 255 parameter mentioned above but kept having issues.

I hope this helps someone.