Clamp Location Moved, Devices not recognized; Reset or Wait it out?


I’m looking for advise/experience on anyone who moved their CT clamps and whether you reset your Sense or waited for it to re-recognize devices?

I recently had consumption monitors installed as an upgrade to my solar system. During the installation process, the Sense CT clamps had to be moved. As a result, Sense no longer recognizes previously identified devices. Overall production and consumption readings are correct but many, many devices are now bundled under “Other”.

Sense support said I could do a full reset on the Sense or wait it out while it detects devices again. I prefer not to lose historical data (~6 months), though I can certainly export it. I thought waiting for the Sense to re-recognize devices would eventually re-recognize devices. But I’m doubting this approach now as it has re-detected nothing.

I would be great to do a reset w/o losing historical data but that’s a first world problem…

Moving the CT clamps shouldn’t have invalidated your device signatures, UNLESS, in moving them they got hooked on different phases. That would have the effect you describe and I’d bet that was what happened.

Most power monitoring systems wouldn’t care, so most electricians wouldn’t know to keep track and put them back exactly as they were to start with.

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I can only go by what Sense support and documentation says. Electricity is not my area of expertise.

I am going to agree with @andy.

When you moved your SENSE CT clamps, they may not have been placed back on the same LEG or phase as they were originally installed. (Try moving them.)

Also they need to be placed back in the same position. It helps if the CT Clamps are centered on the service wire and at a 90-degree angle to the service wire. Just the smallest amount of change in the angle will affect the readings.

Take your camera and record the setup (before and after) the changes are made.

Learn something every day. I did not realize that the physical position of the clamps on the wires would matter, although I was certain the phase they were clamped on would seriously affect stored signatures. Thanks for the additional info.

One implication of this is that that installations are VERY fragile. The reason is that almost any change in the breaker panel (for example installing another circuit or two) would almost certainly jiggle things around. And, electricians wouldn’t have any idea that their standard practice of “straightening up the wiring” would cause problems.

I’m a EE, but worked for a number of years as an electrician, and we ALWAYS messed around with the wiring in the panels…always to make it better organized and safer. If jiggling the clamps affects Sense’s abilities to detect, that would likely happen whenever the box gets touched.

In July I did some work in my breaker panel. I accidently ‘bumped’ my main CT clamp and did not realize the position was changed. Weeks later I did some more work in the panel and saw the CT clamp position had changed from the original placement.

I restraighten the clamp, then looked at my SENSE APP very closely. During the time period (when the clamp position was altered) SENSE stopped registering my refrigerator readings. After I re-positioned the clamps, then my refrigerator data began to be logged again. Basically I have 3-weeks of missing data on my refrigerator because of a single clamp position being modified. My guess is that the refrig is on that LEG (or phase). The other clamp was not disturbed.

Of all the readings that SENSE takes, it has always correctly identified the refrig circuit. The refrig device was one of the first appliances found and in 3 years I have never had SENSE fail to find it.

Lesson: Be careful when you move your CT Clamps. Small changes can alter the signal pattern.


That’s some key data right there!

Is the fridge the only device not detected during that period?

@JustinAtSense This may be interesting for the team to pursue as far as Sense Labs: Failures (?) may be concerned. i.e. Whether it’s a phantom fridge failure or a “real” one (unplugged/dead) doesn’t matter because it all seems to indicate potential failure of some variety.

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To: @ixu

The only other device that is used often enough to detect an issue and was affected is my TV.

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