You're right to be cautious. While the idea of using multiple loops of wire to amplify the current sounds like it should work with a CT, it NO, won't work reliably or accurately.

Here's why: CT Calibration and Turns Ratio

CTs are precisely calibrated for a specific turns ratio. They're designed to sense the current flowing through the window once. Adding multiple loops drastically changes this ratio in a way the CT isn't designed to handle. The output of the CT will no longer be linearly proportional to the actual current, and the burden resistor (if present) will not be appropriate.

Magnetic Saturation

As the current through the loops increases, the CT core could saturate, leading to highly non-linear and inaccurate readings, especially at higher current levels. The core is optimized for a relatively small magnetic field from a single pass of the conductor.

Loop Impedance and Induced Voltages

Even if you could theoretically compensate for the turns ratio, the loops themselves will introduce impedance and potentially induce small voltages in the circuit, further corrupting the readings. This is especially true if the loops aren't perfectly uniform.

Safety Concerns

While you're planning to de-energize the circuit during installation, any kind of jury-rigged setup around high-current conductors presents a safety risk. A loose connection or insulation failure in your looped wires could lead to a short circuit or other hazardous condition.*

Accuracy for a "Charity Job"

If this is a charity job and you want to provide any data/insight, relying on inaccurate data from the set-up you propose is probably worse than getting no data at all.

Instead of the multi-loop approach, consider these alternatives (in order of preference)


Borrow/Rent Larger CTs

Contact electrical supply houses or even local electricians. Explain the situation and ask if they have any loaner or rental CTs that would fit the conductors. Sometimes companies are willing to help with charitable projects.2.

Postpone and Rescope

It's better to postpone the project and either find a way to get correctly sized CTs or re-evaluate the scope to see if there's another way to accomplish the goals without current monitoring.3.

Estimate

If the purpose of the CTs is to get a general idea of load, can you estimate the load based on the connected equipment and typical usage patterns? This would be far more accurate than relying on bad data.4.

Use a Clamp Meter Temporarily

While not ideal for long-term monitoring, a clamp meter around the conductors for a representative snapshot of the current might be better than no information at all.

In summary: The multi-loop idea is not a viable solution for accurate current measurement and poses potential safety risks. Prioritize finding correctly sized CTs for the conductors. If that is impossible, re-evaluate the project and decide whether the goals can be achieved without current monitoring. Flag for review