Detect an energized wire with a CT or NCVT?

We have a 12kW stand-by generator with ATS (automatic transfer switch). Inside the house I want an LED that indicates when the mains/utility power is on or off, and another LED that indicates when the generator is running or not.

I want to use your CTs with an Arduino Nano inside my ATS box, to detect an energized wire, and sometimes there is no current flow through the wire but it’s still energized. I was looking at these:
ECS24-200 (for the mains/utility power wires)
ECS10-50 (for the generator power wires)

I though about putting a NCVT on a long wire, but I think a CT is more reliable. Is it possible to use a CT to detect an energized wire, even when there is no current flow?

I would call that a paradox. But I think I know what you mean to ask. You can detect whether a wire is carrying an AC current with a CT. Maybe you don’t need anything too fancy. Take a look at this.

Oops, should have asked how to use the CT to detect an AC energized wire without a load. I also forgot to mention the ATS is outdoors near the generator and anything I do should be rated for at least -20F (-29C) temperature, being in Vermont.

Since your CTs output mA current, I would need to convert this to a voltage with a 20 Ohm burden resistor, before connecting to Arduino?

Is the CT sensitive enough to pickup the AC frequency “vibrating” at 60 Hz, even without a load?

The CT senses current. If there is no current… no output. Sounds like you want to check for voltage, which should actually be a lot easier.

Good luck.

Found a possible solution here.
https://www.jameco.com/Jameco/workshop/JamecoFavorites/non-contact-AC-voltage-detector.html

You didn’t indicate what kind of budget you had in mind, nor what kind of accuracy was necessary. One really simple solution is two 5V USB chargers. One is plugged into the main power (before the ATS) and the other is plugged in after the ATS. This is a simple low voltage connection (output of the USB charger) to your Arduino. You probably already have a box full of old chargers. When on main power, both chargers will be outputting power. When on standby, only the standby one will be on. Assuming that your Arduino is powered by the generator, you could eliminate the 2nd charger and just assume the generator is on if the Arduino has power.

I think I can do this without an Arduino. The generator has a 12V battery that I will use to power the two non-contact voltage detectors (NCVT) inside my automatic transfer switch (ATS) and the two status LEDs in the house. Then I can see if the mains power is on or off, and if the generator is running or not. My budget is less than $25.

Here’s a fancy commercial product, for standby generators, that costs $300 plus $25/month subscription.
Briggs & Stratton InfoHub™ Universal Wireless Monitor For Standby Generators
https://www.electricgeneratorsdirect.com/Briggs-&-Stratton-6574/p105145.html