SENSE on commercial panels. 225A, 240V/3-phase. Is it possible/legal?

A couple very specific questions that I suspect have been answered in some form already on these forums.

Could a SENSE unit monitor a 225A, 240V/3-phase panel?
If not, can anyone recommend an alternative solution that could provide aggregate historical tracking at minimum?

Are there any other legal implications for having SENSE installed in commercial panels? Are they certified regardless of whether its a residential or commercial install?

I’m located in Quebec, Canada for what its worth.


Any idea about this or is it a question better directed at Support?

The location I’m hoping to use SENSE with is a large A/V install that would involved monitoring 6-8 different panels. Not being able to access them under one account isn’t ideal but wouldn’t be a deal breaker. We more so just want eyes on all of it since the aggregate usage is going to result in a power bill that could climb into the 6 digits annually.

I don’t think this would be a great solution. Aside from whether or not the calibration of the unit can handle 240v as its mains voltage, you would need a lot of Sense’s to make this work. In concept, if the Sense can handle 240v single phase, and the software calibration would work with that, then I would think you would use 1 sense per panel. Ordering a set of the Flex CT’s and using one of those in the 400amp split service configuration. One CT would just end up hanging unused. So for instance, main CT’s around Phase X, Y and one of the 2 Flex CT’s on Phase Z.

But that is really just a guess. I would reach out to support and get their point of view.

As for an alternate option. Its not nearly as pretty as Sense, and is significantly more expensive, but Monnit makes a large array of sensors, including three phase monitors.

I have not used their power monitors before, and it may not be a good fit since I think in general, their system is based on a slower interval polling vs live logged data, but it may be worth taking a look.

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You probably want to check with support. Several Sense users are using Sense to monitor their two phases of the commercial three phase supply, including @ixu.

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If this is for monitoring AV equipment, I don’t think Sense is a great match, since you won’t get device level details on switch mode power supplies. You will be able to successfully measure power usage on 2 of your 3 legs, but I don’t think the product is listed for that application, so you may run into issues with your AHJ if this is being inspected.

Depending on your exact confguration, there are a variety of products aimed at the datacenter industry for circuit-level monitoring in 3 phase panels. Also, if you have PDUs in your equipment racks, you can replace them with network-connected metering PDUs, which will measure the consumption of the whole PDU and/or individual plugs, then feed all your data back to a variety of logging softwares.

Or, if you just want panel metering that’s network connected, check out EKM metering.

As mentioned, Sense can be used to monitor 2 of the 3 legs with the caveat that you won’t see consumption from the 3rd leg.

Anything outside of that configuration not been tested widely. @ixu may have some additional wisdom to add here, as @kevin1 mentioned above.

I think this is your only practical option and it could work (AFAIK) but with caveats:

  • Sense is calibrating (to 208V/120deg phases in my case, as @kevin1 quoted ) based on your input voltage across both legs (although only powered from one), right @JustinAtSense?
  • The panels are going to have a mix of use of the three phases, 120V on any given phase for single phase circuits (devices/breakers); 208V for dual-phase. And let’s assume you don’t have any 3-phase motors or gear … or do you? Anyway, detection on any X-Z or Y-Z phase is not going to happen.

If you’re OK with just clocking the watts it could work (inelegantly) but, thinking out loud, there is a way to perhaps do that more efficiently, using Sense, if you can be “upstream” on the panel feed wires, where you can physically clamp multiple wires … current and wire gauge-permitting you could use 4 Senses for a total of 8 “dedicated” (Flex) CTs. Clamp the CT around the 3 (live) wires in each panel. You’d probably want to create a dedicated kind of “passthrough” panel for all that with the Senses in it and so you’re looking at some tricky “local electrical code” issues! I’d go on about using the Main CTs for redundancy or selective detection but you get the idea.

FYI: A Fluke 435 is a nice tool and something an electrician might use to temporarily log and balance phases and whatnot. That’s not something most can afford to leave “dedicated” but at some point in all the fiddle there are situations where a Fluke 1736 or 1738 could interesting.

I agree with @pswired, you have more commercial options.

Monnit, as @ben points out, is a possibility and I use their sensors (very effectively) in a number of building monitoring situations but not for current/energy monitoring due to expense and limited capability. That said, if you care about heat/fire/water they are my go-to: e.g. I’ve got temperature and humidity sensors in racks and panels and water sensors in electrical rooms. Typically these are redundant with sensors that are often built into commercial gear. If you are dealing with a bunch of expensive and/or critical gear and NOT doing redundant monitoring then you are probably doing something wrong. Sensors tend to pay for themselves by saving during a single “event”.