Using single flex ad on clamp to measure sum of two same phase conductors?

Can a single Ad On Sensor clamp be used to measure the sum total of two same phase circuits by passing both conductors through the one clamp? I’d prefer not to waste both clamps on this one task. The two circuits are separate 20 amp feeds on the same side of the box (same phase) for two large audiophile amplifiers which are always run together.

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Should work. I’ve done it many times with other CTs. The physics are the same. Just need to really be the same phase and if you are bending conductors makes you keep the orientation the same.


I’ve done this with my Sense, but only with a 220 circuit.

What are you trying to specifically measure?

Assuming that you are in the US, most residential panels are not split by side of panel. The mains lines alternate ever other (or every third for 3 phase) breaker position. So do be sure to check if they really are on the same power leg.

But as others have said, as long as they are on the same leg, and power is flowing in the same direction, yes, the CT will measure both.


I’m trying to monitor the total draw on two 20amp 110v breakers that power two large class A audiophile stereo amplifiers. Not that I’m going to listen to music less but curious how much they really draw (which I’m expecting to be a LOT :open_mouth: ).

Yes, I meant “Logically’ on the same side of the box. Same phase by design. I installed these two 20amp breakers years ago for two large audiophile amplifiers and specifically wanted the entire audio system on the same phase for anti-hum reasons. The two breakers are in fact one breaker apart from one another physically.

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I’d use a smart plug, KP115 or HS300.

I have my variable pool pump, wired into an HS110.

Unless your equipment rating exceeds the smart plug safety rating.

I’m doing this with my indoor and outdoor hvac. I have one ct monitoring the same leg of each circuit. Shouldn’t make a difference if it’s 220 or 110.

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They each draw 1380 watts at idle! I don’t think a little plastic KS115s it going to like that for very long. They are each plugged into a dedicated 20a hospital grade outlet on separate 20a circuits.

Just wanted to report back that the single clamp on multiple, same phase circuits works great. I even decided to triple up. There are two 20amp breakers that each run the large power amplifies and a third 20amp breaker that runs the rest of the component rack. Since all three are on the same phase in in relatively close proximity on the panel, it was easy to neatly route all three conductors through the single clamp.

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Now the fun begins…


@Offthewall Glad the config worked out. I have been debating on what circuits to monitor separately myself. I decided to go with my indoor and outdoor heat pump units on one ct and my hot tub on the other. I may end up moving these around as sense learns the devices. I will probably keep them on the heat pump since I’m not really concerned about individual contributing devices for this unit.

It would be nice to create a “virtual device” and group the individual items like you can on a smart plug or dedicated ct as Sense finds these devices.

Yeah, the left clamp is presently on the furnace. I’m hoping eventually Sense will ID that and I can use that clamp on something else. The triple circuit audio system setup is permanent. There is no way Sense would ever be able to ID that stuff.

I am using this approach to handle my solar which has two inverters. Functional and accurate.

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Does each inverter not run into a single circuit breaker on your main panel? My setup has two inverters. Each runs into its own 40 amp breaker in a sun panel and then the sun panel feeds into the main panel using an 80 amp breaker. The solar CT’s are connected tot he 80 amp breaker.

One in the main panel and one in a sub panel. It’s a somewhat complicated setup due to limited space in the main panel, plus two large solar inverters and a generator ATS.

After my success with using one CT clamp to monitor the sum of three 120v circuits, I got creative on the other CT clamp.

I was using it to monitor the Furnace on a singe 120v breaker. What I really wanted is the total of the Furnace and the outside 240v AC compressor.

I set up the 2nd CT clamp as a 120/240 monitor. Passing the Furnace 120 conductor and the same phase leg of the 240v breaker in the forward direction through the the clamp and then looped the other phase of the 240v breaker backwards through the clamp (see pic).

It seems to work great. The increase in the main leg totals match the increase when either just the furnace is running or when both the furnace and AC compressor are running.


@Offthewall I had to get out my calculator and do some vector math :joy:. It looks like you have all three legs in phase with each other now so they should sum up. Nice job!

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Very clever setup with the reverse loop…