Another issue and question

Man I am trying so hard to make this work

From Sense
We've noticed that your Sense power wires are drawing from the same phase, or leg, of your electrical panel. It's possible that the power wires were either installed on a tandem breaker or, if you installed on a 240V breaker, Sense is sitting on two slots that occupy the same phase/leg of the panel.

The Sense breaker is on the last slot.
I am using a QOT1515 Tandem mini circuit breaker. Is the type of breaker OK to use or should I use a different one (Has to be mini)?

The Panel serves for the second AC and Tesla Charger it is also wired so we can plug in a generator if we lose power and is feeds the inside panel for the rest of the house (Transfer Switch)

If I try to use the next breaker further up on the buss bar, how will I know if it is pulling from both legs (or do I inform Sence tech I have made the change and wait for a response)?

If the new location does not work, can I tap the AC breaker or the Tesla Charger Breaker?

Those are my only options as the panel was designed for a “plug in generator” to power certain items if we lose power (Florida Hurricanes) and I don’t have any additional live buss slots.

Only one photo this time :grin:


What you call a double breaker is really called a “tandem breaker”. It occupies a single slot, has two breaker switches, and allows two circuits to be attached (to the same phase), each protected separately. What is above “new circuit” and on “car charger” are what is called double pole breakers. They are meant to supply both phases to a single circuit and protect that single circuit as a whole.

Panels have “slots” for breakers. The slots alternate what supply phase they are connected to. This is what allows a double pole breaker to attach to both phases (as it connects in two adjacent slots). A tandem breaker only connects to a single slot and thus both circuits will use the same phase (the location of the breaker in the panel dictates which of the two phases). Thus the two lines attached to “Current slot” use one phase, the two lines attached to “New Slot” use the other phase.

“Current Slot” provides two wires (to sense) and by virtue of it being on a tandem breaker, they are both on the same phase. This then also explains the error message you are getting… Sense needs to be supplied with 110/120V from each phase as a reference so it can observe what is happening to each phase. This is why they are complaining.

The “car charger” breaker is a double pole, providing two different phases, one to each connection. Thus the car charger sees 240V (as it should). The breaker above "“New Slot” is also a double pole breaker.

So you need to get a new, double pole breaker, like the one for the car charger, 15A capacity should suffice. From the picture it looks like your panel can use Schneider Square D breakers (or compatible). It can go right below “Current slot”, or right below “car charger”. Remove the red/black wires from the breaker in “current slot”, and then connect the red and black wire currently on the “Current Slot” to the two terminals of the newly installed double pole breaker. Finally, if you so desire you can remove the tandem breaker for “current slot”.

It is fairly customary to use one color for one phase, and the other for the other, consistently. Your first two double pole breakers have black/red in the same position. Notice the car charger uses two black wires so no telling which one is which. This is perhaps unfortunate, but it works just fine and you don’t want to call out an electrician to replace a black wire with a red one. It might be consistent, once connecting to the new double pole for sense, the keep black on top, red on bottom. If you re-use the tandem breaker in “current slot”, ideally you should use two red wires for whatever you plug in.


Thank you for that clear explanation.

My issue was I tried to install another tandem breaker (before I knew I needed a double pole) below the Current slot but I don’t think the buss bar extends down any further than the current slot as it would not clip in (I did not try the slot below the car charger).

The current slot was used for another circuit that kicks in if we lose power and plug in the generator and is in the off position (until the generator is used) I just used to try to get the Sense up and running.
So ideally I would prefer not to use that slot.

As a last resort the car charger is a 100amp can I drop that to a 50 amp and piggy back off of it?

Anyway off to the depot to get the correct breaker and hope there is a live buss below the car charger.

Well, that is a very good point. I never looked close enough to see if there would be space. Looks like there might not be! This is an awfully small panel. I am going to guess that the breaker above “car charger” goes to a sub -panel somewhere. Otherwise I cannot see how one would run a house off of this!

The car breaker being 100A seems incorrect. The max car charger current that I know of is 48A, and the rule is that no more than 80% of the rated current for a circuit can be used. That would mean a 60A breaker. It is impossible to see in this picture, but the additional question is whether or not the wires attached are even of a gauge supporting 100A. If not, this would be not according to code.

Piggy backing off another circuit, while technically possible may also not be up to local code. Besides it may confuse sense if it is not on its own, completely separate, circuit.

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And yes it is a sub panel serving one A/C, the Tesla Charger (1st Gen) and the main panel via a generator (when the power goes out)

I installed the car charger back in 2014 when Tesla came out with the P85D back then people said use a 100amp breaker to get the max amps from the charger. I think it maxed out at 80a (but I may be wrong)
Now in 2023…OMG was it that long ago… we get a maximum of 48amps

I have a sparky lives a few door down so I’m gonna enlist his help.

Again thanks for the advice

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Yes, I did not think of the older Tesla models that could go higher! If this is indeed a sub-panel (i.e. not where the main supply comes in), you will want to install sense on the true main panel, not here.

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That’s were I had originally installed it but I miss the second A/C and car charger which are two big power suckers.
I was hoping that this would pull data from the latter and the main panel if not I guess???

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2 posts were split to a new topic: Repeated Notifications - What’s Going On?