Real time and Historical Amperage Draw (Generator Use Case)


I wish Sense could display in real time (at least) and record (best case) amperage draw.

This would be helpful to those of us who use Sense to help size our generator needs in advance of making that major purchase. It would also help monitor our loads after a generator is installed. Sense device detection may also help inform better decisions on how to configure load shedding. Measurements in amperage would be typical in this case.

From a business perspective, generator users spend thousands of dollars on their solution. In many cases, a $300 investment in Sense is worth it just to size their generator correctly before making such a significant purchase. Users with an ATS installed at the service entrance will automatically benefit from Sense with no extra effort. Users with a transfer switch installed via a back fed breaker may be able to benefit from the solar CTs when on generator power.

I think this type of feature and some marketing would help expand the Sense community.


Hi Bill,

What am I missing here? If you know Watts, which Sense displays real time, and you know volts, which they also display on the Settings->Sense Monitor, one can easily calculate amperage. In the snip below, the total amperage draw is 5.9 amps. I agree it would be nice to be able to have the data stored or exported to a csv type file.


What is “best case” ? The high water mark (max instantaneous power/current) for all time ? Or for some fixed period, like the typically worst case month/week/day (the time your, washer, dryer, dishwasher, pumps, jacuzzi, toaster, instant hot water, power tools are all going) ? Do you want to capture the max, max peak of a millisecond spike that is 3x higher than any other current or have Sense do some smoothing ?

I ask all this, because you have a pretty good proxy in looking at the highest hourly usage over whatever period you want to consider, then dividing by 120V to get amps, then multiplying by some safety factor to take into account your ratio between steady state power and instantaneous peaks.



For that screen, you are correct. It should be simple for the user interface to do the calculation and display it automatically.

For information displayed on other screens, I don’t think the voltage is immediately apparent. Some devices might be using one leg and others using both legs of the service. In my view, it’s just a cosmetic issue that would be a helpful addition to the UI.



I would say recording the max and average draw in amps would be useful.

It’s not easy to get historical data out of Sense mostly because there’s no search/filter option. I imagine if Sense released a “Reporting” module, it would be an entirely different situation.


Ah @bill1, I understand better now. Thanks for the clarification. I agree it would be helpful, especially since only we know what devices are on what circuit breaker, it may help determine if we are pushing the breaker load limit.



One more question. What would you search for if you had a spreadsheet of minute by minute power samples (or would you prefer second by second power samples) for your entire history ?

And what window/granularity would you like your averages at ? Sense essentially gives us hourly/daily/weekly/monthly averages in the Usage panel. Sure, you need to divide the energy used in that period by the number of hours in that period to get power, then by 120 to get amps, But again, I’m more interested in how you would select the sample period for the average calculation.


Minute by minute is more than enough. The only exception is (especially for generator users/dealers) recording peak info at the smallest time interval possible is desirable. This only matters for devices that are motors like an HVAC compressor.

Putting aside capturing peak starting amperages, hourly/daily/weekly/monthly averages are fine. For generator sizing I basically want to know: what’s my worst case scenario when a motor starts up and what is the steady state (assuming there is one) once the motor is running.

It helps to know that heat pump X uses 10 A to start and 5 A once running.


Thanks for the explanation. You can kind of get spike and steady state profiles of individual motors, just by turning each one on, when other things in the house are bit quiet. Or by looking at the profiles once each motor is correctly detected. But do you then sum up all the worst case peaks and add them together, presuming that they might all start at the same time, or do you add the biggest spike peak to an average for the typical worst (most usage) hour in your house, to get a reasonable maximum.


Yeah, I get what I need out of it like you describe. I guess my bigger picture point is that a lightweight feature or two might help cater to an additional type of customer.

Support emailed me today. While the solar CTs can provide total current on a back-fed breaker to a generator, device level detail can only come from the main CTs, which would show no current in this scenario. FYI to others searching this later.


Agree - I would like Sense to be useful to as wide a swath of residential customers as possible.


@kevin1 . Yeah - Sense might find that generator dealers can be a channel for the product especially those doing standard service entrance ATS installations where you can use the main Sense CTs regardless of the power source.