Mystery Device (Solved!)


Despite suggestions to not move the Sense to a different 240 breaker, I proceeded with this approach to helping solve the issue. After moving to a new breaker and powering back up I could see that I must have gotten the polarity wrong because I was getting negative wattages. I switched the leads and then all devices were showing properly. I then was able to power off the previous 240 breaker that the Sense was tied to.

Lo and behold I still had the mystery device showing up. This meant to me that the mystery device was not tied to any of the 240 breakers in my box even though it was pulling 240 v. This could only mean that someone , many years ago, decided to use 2 separate 120 breaks to create a 240 supply. Turns out I was right. the picture below shows which 2 120 breakers were being used.

I suspect this is not up to code :slight_smile:

In any case this led me to to the culprit which is pictured below:

This is a heater that is mounted in the wall in a sunroom off the back of my house. There are no switches or thermostat that control the heater that I have ever found so I assumed it wasn’t a working device. This was done over 25 years ago( before I moved in) and the previous owner gave me no information on the system.

Mystery solved … I think :slight_smile:


Great job piecing together the clues. You win the “Best Home Forensics Award” for the month ! Sense, finding devices you didn’t even know you had :wink: and it was right about the Heater Part.


Nice job finding the device. Handle ties are made for your application. Here’s an example (this is not a QO panel like yours, but I think they’re available for QO tandem breakers as well):


I personally don’t like 2-pole loads on tandem breakers, and would encourage you to shuffle circuits around so that your tandem breakers serve only 120v loads, and then purchase proper 2-pole breakers for your 240v loads.


Great work @michael.haws
In your case, Sense led you to find a serious problem in your panel. I can tell you from experience working with insurance companies that had an electrical fire happened and they found this, they would have not paid the claim.
It’s an easy remedy, replacing the two single pole breakers with the appropriate double pole. You got your moneys worth out of Sense for sure.

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Good catch! And, that heater was devouring your KWH.

With the handles tied together, this IS a two pole (e.g 240 v) breaker…it was done this way for decades. When either side trips, the handle moves a bit, causing the other side to release too. They are still very much in use, and you can buy the handles at any big box store or electrical supply shop.

Be cautious though, from what I’ve read, not all manufacturers single pole breakers are rated for such use (depends on how the trip is done). And, a new dual pole breaker for your panel can be bought for under $20, so I’d replace this if I were you, assuming you want to keep using the heater at all.


What you have a SQUARE D brand breakers in the “homeline” model category.
Lowe’s has a double pole 20 amp breaker for $9.25, Lowe’s item number 13317
It does appear that you are out of slots and the bottom breakers you are pointing to are slim breakers for this purpose. To add a double you will probably also have to use a couple more slim breakers to have room.


Wow, awesome work on this!


I didn’t look closely enough. Sorry.

What someone did is to tie together the two inner breakers from a couple of two circuit single pole (often called minis) breakers. That’s not at all the same as tying together two standard size single pole breakers with a proper handle and I sincerely doubt these are rated for using a handle between them. I can’t find anyplace that says doing this is OK, and as an electrical engineer/electrician for decades, I’d not dare to do this.

So, you are now faced with a bit larger project to get rid of this problem. Assuming you do want to keep the space heater, you would need to pull out these two minis, replace them with a dual pole breaker ($10-20 at your big box), separate the two minis from the handle, and then use the minis someplace else in the panel to provide the then missing two additional single pole circuits. All together, being careful, this shouldn’t take more than a half hour or so and $10-20 to fix.

A HUGE problem with older (and some cheaply built new) homes is inadequate panel space for modern consumption patterns. That’s why minis were invented as a workaround. But, they are intended to provide two separate circuits (on the same phase) in what is a single pole slot. This gives you twice as many circuits in the same panel space, helping to resolve the problem. It does (or should do) nothing to resolve the double pole space problem.


I think the breaker was manufactured that way as a triple breaker. If you notice there is 240/50 in the middle and 2 120/20 amp on the outside. By using the breaker it gains a slot.
What I would do is take that bottom breaker and move it to the upper right 2 slots where there is a 50 now. Then take the next 2 20 amp breakers out below the New tip breaker (from slots 3 and 4) and use those wires in the outside 20 amp terminals of the new top breaker. Replace the standard 50 amp to the bottom right slots where the breaker was removed and I assume was for basement stove. Then take the empty slots 3 and 4 on right and install tour new sense double breaker there. This would require the purchase of one breaker at less than $10


If just a case of a mistaken identity, then why move it at all. Just notice (and perhaps a note on the board for the next person) that this is really three breakers, a dual pole and two single poles, with the dual pole driving the heater panel. No time or cost then.


He had stated putting sense on its own breaker but by the picture, he doesn’t appear to have room


@andy, it is the two single poles that are driving 240v heater panel :frowning:


@samwooly1, you are correct there is no room for sense to have it’s own 240 breaker, so I just moved it to a different 240 breaker.


You do have room but will have to purchase a few $7 slim breakers. It will likely completely screw sense up. I think you could do like I plan on doing and that is to twist tie (with wire caps)my sense and water heater wires together with an added wire as a pigtail to insert into the breaker. Doing it this way is still within NEC (National Electrical code).
If you have two wires inserted into a single hole on a breaker, that violates code and is known as double tapping.

split this topic #75

A post was split to a new topic: Mystery Device identified as Water Heater really a Wall Heater