Flex Add-On Sensors

A little confused about them. First of all, from the photos I’ve seen, there appears to be 2 flex sensors; so you get 2 sensors for $50? Also, I understand that the sensors plug into an unused port on the main box, so how can 2 sensors be connected to only 1 port. Finally, I want to monitor 1 240v circuit and 1 110v circuit; is this possible with the flex sensors? Thanks!

Well, here it is:

  1. Yes, 2× sensors and one single connector. However, the connector has 4 wires/pins in it, both sensors connect to the same connector, which then plugs into the unused port of your orange box.

  2. From what I understand thus far, monitoring a 240V will requires either 1 or both CT sensors. It all depends on whether a neutral is used, and on the specific wiring of your electrical panel.

Also, check out this link. It should provide the answers you seek.

2 Likes

One addition to @drjb’s excellent commentary. If your 240V circuit is balanced (no neutral, typical for AC compressors and EV changers), you can do a combination of monitoring one 120V circuit and one 240V circuit. The real trick is that the 240V CT will only be on one of the two hots, so the current flowing through each hot has to be the same (or very nearly the same).

2 Likes

Thanks to both @drjb and @kevin1 for your informative replies. I’ll have to check my panel next to see how the 240 is set up.

1 Like

If you tell us what type of 240v load you’re trying to monitor, we can likely tell you if it’s 240-only (no neutral, only need 1 CT) or 120/240 (neutral in use, requires 2 CTs).

2 Likes

Thanks! Here’ a photo of the connection in my breaker panel. It’s for a GE clothes dryer. Based on the installation instructions for the Flex, and this photo, I’m going to guess that I’ll need both sensors to monitor the dryer. It must use 220 for the heating element and 110 for the motor and light.

1 Like