Installed a Sense this weekend on a 400a electrical service

I thought others might find this information useful.

I was able to install a Sense unit on this 400a (well technically “class 320” meter whatever that means) this weekend.

Now technically there are a few challenges with this installation:

  1. You need power company cooperation since these CT’s are in the locked side of the meter can
  2. The Sense CT’s are technically only rated for 200a - it is unclear how things will look when current goes over 200a - this will be rare, but on this install it certainly could happen
  3. The Sense unit is probably not technically rated for installation in an outdoor cabinet - we will see how durable it is temperature wise - while this is a nice tight enclosure, it could get hot in the summer and cold/humid in the winter

For those that might find it useful: The Sense CT’s fit just fine over the 350 MCM Aluminum cable that the power company used to feed the meter pan.

Note that we did use a snap in plastic bushing between the two sides of the meter can so as to not abrade the CT wires.

It is working perfectly so far!

I ran a ton of load last night as a test. I could have fired up another 40kw worth of furnace heat strips, but I figured that would be really mean to the power companies 25kVA transformer.

I would love it if Sense made some CT’s that were actually rated for 400a, and perhaps options for larger CT’s as well such that you might be able to get multiple cables through the same set of CT’s in some installation situations.

Also, this installation might be able to be accomplished (without having to get into the power company side of the meter pan) by using two sets of 200a CT’s - perhaps one plugged into the main CT jack on the Sense, and the other plugged into the Solar CT jack on the Sense? Not sure if the two jacks are calibrated differently or anything, but that could be a slick way to support 400a services in some situations.

Oh, and we did clean up the install before we were done, I just wanted to show the part where the meter can was open.


Nothing “bad” should happen if you hit the 200A mark, i.e., nothing dangerous. You’re probably aware of that, but I should make that clear for everyone else. Still, we do not advise it as it’s beyond the CT rating (higher rated CTs are certainly possible in the future). Above 200A, you’ll likely see clipping in the Power Meter and device detection could be negatively affected.

As for outdoor installs, we actually do have guidelines for these at the bottom of our Compatibility page:

Thanks for the clarification on outdoor installs! Glad to see that Sense supports them (within certain limits).

Does the Sense unit have a temperature sensor inside of it somewhere? If not an ambient temp sensor, then perhaps one of the chips or the CPU you are using has something built in?

It would be interesting to see graphs in order to understand how hot/cold the unit is getting.

We do not have a temperature sensor on the monitor. You could utilize something like an Elgato Eve Degree or other connected temperature sensor though. There’s some pretty cheap ones out there.

I know you are looking for an on-chip or on-board monitor, but I have started using an Ecobee remote temperature probe for watching the ambient temperature in my service closet, where my Sense is located, so that I can have a time history of temperature.

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It would be really nice if they just had multiple units that could display on one page… Right now I have two sense accounts one on each 200amp panel.

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Here’s current results of my experiment with using an Ecobee sensor for monitoring temperature in my service closet where my Sense is located. The only issue is that the sensor is far enough away, and the service closet generates enough EM noise, that the sensor burns through a battery each week, instead of every 6 months to a year for the rest. Just replaced the battery a third time, but it is worth it to get a view of ambient conditions in my service closet. Right now the temperature varies between 50 degrees and 80 degrees.

For those looking for temperature sensing and logging, take a look at the LaCrosse Alert hardware.

It’s inexpensive, they offer a variety of hardware for different tasks including secondary probe capabilities on many of their sensors, and there is a subscription service that offers enhanced functionality so far as alerts.

However even the free service does provide logging down to a 15 minute scale if desired.

I use 3 of their sensors to monitor various things including our pool and hot tub temps, outdoors, indoors, etc.

Thanks for the recommendation - for now, I’m just going to keep on going with the Ecobee sensor, mainly because it works OK (as long as I keep it fed with a steady stream of button batteries), plus the data comes alongside the outside temperature in the Ecobee reports. Once I get enough data, I’m going to try to fit a simple outside temperature / sunshine vs internal temp model.

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