Advice on using resistors to merge pairs of CTs

Just picked up some 20Ohm resistors for merging 240v CT circuits into single inputs. My plan is to take the 2 50amp CTs on my oven, and connect to a 3 way splitter, with the third jack filled with a 3.5mm plug connected to one of those resistors.

A couple of dumb questions. Once I’ve wired that up, I assume I just set the burden resistor setting for that input to 10ohms, and that I’ll now I’ve set it up correctly if the expected wattage reports as it should. Is there any way I can screw this up that would damage the Iotawatt or the CTs?

-Anything wrong with cutting up some old headphone cables, and just using the existing wires to connect the resistor (as opposed to ordering jacks, and soldering directly to the resistor)?

If the external burden isn’t properly connected, you could overdrive the input and exceed the power rating of the internal burden. I don’t think it will do damage but wouldn’t do it anyway. The CTs have a three conductor jack, but the current is carried on the tip and sleeve.

Connect the external burden between those two.

You can leave the burden set to 20 Ohms and check double, in which case the Amps indicated will be the average amps on the two CTs. If you set the burden to 10 Ohms and leave double unchecked, the Amps indicated will be the sum of the two CTs. In both cases the Watts should be correct.

Electrically no. Sounds like a bit of a mess and you have to be sure to get the correct two wires of the three.


Opted to do some surgery on the cable I had and just go directly onto the jack. Not exactly pretty but it gives me 20ohm between the tip and sleeve on my multimeter.

I like the artistic background. You could call it art.

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Actually it just looks like a piece of OSB.

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