Power and voltage reference for two IoTaWatts using splitters?

I’m thinking of bringing online a second IoTaWatt to measure more circuits.

Is it possible to power both and provide the voltage reference for both with splitters? E.g.:

Voltage reference:
3 Ways Daisy Chain Power Cable DC…
Arduino Power Supply Splitter…

microUSB splitter:
MicroUSB female to 2 MicroUSB male splitter…

You can split one but not both. My recommendation would be to split the AC ref with a CCTV DC splitter cable and use separate USB power supplies for the two units.

Not the OP, but out of curiosity, why can’t you split both? Just want to understand the technical limitation for my potential use case(s).

Creates a ground loop


Is the ground loop relative the USB V- or USB shield? Some devices bond V- and shield, does the IoTaWatt?

I ask because I’m trying to fit this into a recessed enclosure using a USB receptacle since I’m not sure I can fit the USB adapters. The receptacles generally have a pair of ports with isolated V+/V-, but usually bond USB shield to earth ground.

I don’t know. Schematic for ESP8266 is open so you can look it up. USB plugs are for chargers. I recommend actual power supplies. They are pretty small.

Just closing the loop on this one. The ESP8266 has a few design variants, but USB shield does get tied to system GND in some of them. Therefore, I agree with you that using a USB receptacle (with USB shield bonded to earth ground) is unwise.

I have switched to a larger enclosure and will be using USB power supplies (though probably will need to get ones with cords exiting vertically, but that shouldn’t be difficult). Thanks for the tips!