Pre-order sanity check

Support
1

I’m in North America with a typical 120V split-phase system. I have two independent 150 amp panels in my home, served from a single meter outside. On average, I use a bit over 70 kWh/day. About 15-20 kWh of that is to charge an electric vehicle. The majority of the remaining 50 kWh is probably for my 8.5 tons of A/C, but still I’d like to verify this.

I plan to order the following to better measure where all this power is going.

  • Two North American bundles, with split-core CTs for the mains.
  • 16 x 50 amp CTs which I will use to measure the following circuits:

Panel A:

  • Oven on a 120/240V 40 amp circuit (2 CTs)
  • 1st floor air handler on a 120V 15 amp circuit (1 CT)
  • Basement fridge/freezer on a 120V 15 amp circuit (1 CT)
  • Basement air handler/emergency electric heat on a 240V 30 amp circuit (1 CT)
  • First floor A/C compressor on a 240V 35 amp circuit (1 CT)
  • Second floor A/C compressor on a 240V 35 amp circuit (1 CT)
  • Basement A/C compressor/heat pump on a 240V 25 amp circuit (1 CT)
  • Kitchen fridge/freezer on a 120V 15 amp circuit (1 CT)

9 CTs for panel A.

Panel B:

  • Electric vehicle L2 charger on a 120/240V 30 amp circuit (2 CTs)
  • Washing machine on a 120V 20 amp circuit (1 CT)
  • Dishwasher on a 120V 15 amp circuit (1 CT)
  • Second floor air handler on a 120V 15 amp circuit (1 CT)
  • Dryer on a 120/240V 30 amp circuit (2 CTs)

7 CTs for panel B.

I know the 120/240V circuits could be monitored with 1 CT each, but I’m pretty sure I’d have to wire nut extra length onto those wires to do so and I’d rather just clip on an extra CT instead.

I’m wondering if I should order a couple spare CTs to move around other circuits as needed since I can get them at a discount now with the bundle.

If I want to monitor multiple circuits (say several lighting circuits) with a single CT, is it correct that I can place the CT around the wires for the several circuits together, reversing the direction through the CT of any wires which are on the opposite phase? (The combined current would not exceed the CT rating.)

There’s plenty of room in my panels. I can upload pictures if requested.

2

That all sounds right.

I get a lot of follow-up orders for a few more CTs.

3

Great, thank you. Will be placing order soonish.

4

Is there a reason you’re only using 1 CT for each of these circuits? Is your plan to simply double the measured value? That will definitely work, assuming the load on both legs of these 240VAC circuits is identical. Some devices tap 1 of the two legs for 120VAC power for electronics on the device. It would not introduce too much of an error if you only used a single CT. There are a few more options - add a second 50A CT to each of these 240VAC circuits OR use 100A CT’s instead of 50A CT’s, and pass both legs of each 20VAC breaker through the same CT (in opposite directions so they don’t cancel each other out.)

Just an idea… :wink:

5

These circuits are straight 240V so I’m just going to double.

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