I want to monitor (log and display on dashboard) the total power consumption of the panel in my shop building.
I do not have a smart meter
Do not want to monitor individual circuits
My meter is over 200’ away from the shop
Solution that installs in the panel
Preferred communication technology (in order):
Z-wave
Zigbee
Hardwired
WiFi
Prefer to avoid battery powered devices
Prefer to avoid ESPHome/DIY based solutions - nothing against, I just don’t have the time to get into this ecosystem right now
I realize RF solutions in a metal can (load center) may have issues. I can install a plastic enclosure adjacent to the panel and locate the module there for better RF performance - if needed
IP6x rated enclosure (no dust ingress, non-wet location)
OK paying more for robust/well built device I can hopefully not touch for 10 years (or ever) after installation
What I’m imaging is 2 current clamps that I would position around each leg of 240v feeders, pre-main breaker.
I did search and didn’t find anything meeting my requirements. So I thought I’d ask here. Are such posts inappropriate in this community? I read the category description and didn’t see anything prohibiting such requests.
No, it’s fine.
The links I gave you might help, though. I’ve had a lot more practice at searching and I did see a bunch of stuff in that first search string if you don’t get enough answers here.
searched “zwave 240v current monitor” and found this as the first link:
its up to 200A but it’s only 120v. But I think since each phase in a 240v system is 120v to ground then I think it should work. The installation drawings seem to suggest as much.
here is another from the same search:
it’s wifi or ethernet and will do 240v but it’s only rated for 50A
The Shelly looked promising and I’ve reach out to them in the past to ask about split-phase monitoring but they haven’t responded. Their wiring diagrams are Line to Neutral, at least the ones I’ve seen. There is one that shows a 3-phase setup for supplying power to the Shelly, but it’s measuring current phase to neutral. I may be imagining that this is an issue, it may work perfectly fine but for the cost I’d like to be sure before I pull the trigger.
The 50A would be a problem as I’m on 200A service (I should have included that detail in my requirements).
Thanks for the assistance and I’ll post back if I hear from Shelly.
It’s certified european product with certified accuracy <1%. Totally local out of the box( if desired) and has 5y warranty. If you find good alternatives, please update here.
WINNER! I somehow missed your earlier comment suggesting this model. You’re right, this looks like a good fit. I need to read up on electrical code to see if I can run an ethernet line (i.e., low voltage) into the panel.
Thanks for the good suggestion
Update: Just picked up a new, sealed in box unit on Ebay for $80 USD w/ free shipping.
I realize you already purchased a solution but for future interest the Aeotec device would be fine with a 240V split phase installation (from their user manual). Powering the monitoring device itself is 120V but that shouldn’t be a problem.
I assume this means that it will work on the incoming lines of a standard residential split phase 240v electrical installation? So that each clamp is only seeing 120v line to neutral of the incoming 240v line to line voltage?
their reply:
That is correct.
In a standard North American residential setup, you have two “hot” lines (Leg 1 and Leg 2) and a neutral. While the voltage between the two hot lines is 240V, the voltage from either hot line to neutral is 120V.
Individual Monitoring: Each clamp is placed around one of the two main incoming hot wires. Each of those wires carries 120V relative to the ground/neutral.
The Calculation: To calculate power (Watts), the meter needs to know the voltage. Since the meter is plugged into a standard 120V outlet (or wired to a 120V breaker) to get its reference voltage, it multiplies the current sensed by Clamp A by 120V, and the current from Clamp B by 120V.
Total Consumption: By adding those two 120V measurements together, the device accurately reflects the total power entering the home, including 240V appliances (like a dryer or AC), because those appliances draw current from both legs simultaneously.
The difference is negligible from a real world perspective, since they’re both derived from the same center tapped winding. The only way they could be materially different is if the currents are wildly different on the two legs. Which the current sensor would know. This would likely result in protection tripping the circuit. My two cents of course.
I don’t think I’ve ever seen a 240v split-phase circuit with different voltages on each leg.
TBH, I don’t even think that’s possible since the neutral is the 0 reference point between the two legs. It would pretty much have to be nominally equal voltages between the 2 resulting legs or IOW half of the 240v line. I only say nominally because there might be a slight voltage drop on a leg that has a substantially higher load on it or if there is inadequate mechanical connections. But I still think the difference will be minimal even in those situations.
not that the “240v” line is always 240v. it could be typically anywhere between 220v and 240v. but the two legs would always be half of the incoming.
I think…unless you can show how it’s possible otherwise.
Yeah I was referring to it tripping due to the current difference not the voltage. As stated, unless the neutral connection is bad it’s highly unlikely you could see much of a voltage difference between the two legs. If you do, you have a more serious problem. That said, the Aeotec is fine only measuring one voltage and assuming the other is the same. I’m sure the accuracy would be fine for residential purposes. FWIW my ESPHome based CircuitSetup 6 channel unit does the same thing. I believe it has a trace you can cut for an optional voltage sensor on the second leg, but it’s not the default.
