Does anyone have any experience migrating from a Curb Energy system to IoTaWatt? Mainly I’d be interested in reusing the 18 CT clamps that I already have installed in my breaker panel. The Curb CT clamps are two bare wires, but perhaps I could simply wire each clamp to a TS to 2 wire terminal adapter like this: Amazon.com
Also, any idea on which clamp model I would choose during setup? The Curb kit I have has 100A, 50A and 30A clamps.
Thanks!
All I can say is send me a couple and I’ll see if they can be used. Would probably require soldering 3.5mm jacks. Those screw terminal adapters are great, but they are too fat to insert side by side in the inputs that are 11mm on center.
Search for something like this:
3.5mm audio cable extension short
I use those and/or the splitter version with some CTs that I have from a prior system. That provides enough room to use the screw adapters. I was unable to find 3.5mm plugs that worked well. I know how to solder and have a good iron with small tip, but found it too difficult to solder the wires on. I also bought some cables with the intent of using the ends, but those had wires that had very little copper in them, so not really possible to make a good connection.
Really, the CTs that you can get with the Iotawatt are not expensive and probably the easiest solution. How much is your time worth?
Hi, I’d love to hear about this too. Curb has abandoned their old users to focus on Commercial (or at least not residential customers). And with between Curb and SmartThings being mean, I can’t get to that data any more.
I have the CTs in my box and would love to get extensions and plug into the IoTaWatt.
I still need to work on how to power the base unit but using the Curb CTs and extenders will greatly simplify the effort. Maybe even just a wire than can double into the Curb box and extend down to the IoTaWatt base unit would work too… like a cable with jack on one end and bare wires on the other.
PS. Agree the CTs here are very reasonable, just trying to be less wasteful as the Curb CTs would go into the trash.
The Curb CTs might or might not be very good and might or might not be easy to adapt to use with Iotawatt. Curb provides zero information on the specs or type of the CTs that they provide. If they have a built-in burden resistor, something would need to be done about that. Even if they don’t, there would be some need to characterize them so they could be used by Iotawatt. I did that with some CTs from a prior system of mine to get a close enough answer for many things. But, I did eventually send a couple of samples in for a better characterization. I think I got a decent number for the turns ratio, but it was a wild guess on the phase offset.
I would suggest getting new well-known ones for the mains and then send in the smaller ones to see if they are usable. Sometimes old technology is best sent to be responsibly recycled.
Pictures might also help as some at reasonably recognizable.
Hi, finally got around to unlocking my panel and taking these shots. This is probably more of a historical record as these CTs and hub will likely be put in the trash once I get IoTaWatt ordered and installed.
I have the CT clamps from an old Curb system that I would like to repurpose for a few circuits. Did anyone ever figure out if this is possible, or is there a way that I can do testing on the clamps I have to determine the correct settings to use in the IoTaWatt? Thanks.
CTs are pretty straightforward. They either put out a voltage (typically 0-333mV) or a current. If it’s a current, just connect an Ammeter across the output, install the CT on a primary circuit with a known load and read the amps (probably mA) produced. The “turns” ratio is the primary Amps / Secondary Amps. IoTaWatt with 20Ohm burden resistors needs 50mA output.
Looks like it. The voltage, from 0-333mV, should be proportional to the primary current vs the rated capacity of the CT.
Got it. Thank you for the guidance. If a normal CT input has a limit of 50mA, is there a voltage limit for a voltage type CT?
It’s 3.3 V P-P (1.16 VRMS).
So, 333mV should be no sweat then. Good to know. Thank you so much.
As built in the schematic, IoTaWatt requires a current type CT. You would need to remove the burden resistors to use voltage type. You should search the forum for old posts about that. It’s not a very good solution. You would be using only 1/3 of the ADC range.
Yeah, I had read that I would need to remove the burden resistors for these CTs. I was only thinking of re-using my Curb clamps for measuring whole house consumption, as I have Current Type CTs for all the individual circuits. But, I am also going to be monitoring every circuit anyway, so I don’t know that I will even use the voltage type CTs, as they would simply be redundant in this scenario. Lots to think about still. Thank you for your input.
