Distribution utilities lose a large fraction of the energy they buy between the substation and the bill, and a good part of that loss is theft rather than technical loss. This project detects the three common methods: a direct tap upstream of the meter, a bypass around it, and a magnet placed on the case. It does so by measuring current at two points and comparing them, by comparing phase current against neutral current, and by watching a magnetic sensor and an enclosure switch — then reporting each event with a timestamp. The engineering that matters is the threshold, because a detector that cries wolf is worse than no detector at all.
Not just the parts. Teams budget from a component list, then run out in week six on wire, connectors and the driver board they destroyed. These are the lines that catch them.
| Line | Cost |
|---|---|
Components and materials From the bill of materials | Rs 4,080 to Rs 10,160 |
Spares and replacements 15 % — you will destroy something | Rs 612 to Rs 1,524 |
Consumables and hardware Wire, connectors, headers, screws, heatshrink | Rs 490 to Rs 1,219 |
Perfboard and assembly | Rs 150 to Rs 400 |
Report, printing and binding Two or three bound copies, plots and the plagiarism check | Rs 400 to Rs 1,200 |
| Total | Rs 5,732 to Rs 14,503 |
| Each, split 3 ways | Rs 1,911 to Rs 4,834 |
Indicative bands last checked in August 2026 — a guide, not a quotation. Prices move and vary by seller, and anything you can borrow from the lab comes straight off the total. The 3.9 week figure assumes 9 person-weeks of work shared between 3; students past 4 add coordination rather than output, so the estimate stops improving there.
The same chain in words
In a healthy installation, everything that passes the feeder-side CT also passes the consumer-side CT. A tap between the two shows up as a persistent difference between the readings.
A direct tap between phase and neutral downstream of the meter shows up differently: the phase current and the neutral current no longer match, because part of the return path bypasses the measurement.
A magnet placed against a meter influences some meter mechanisms directly. Detecting the field itself, rather than its effect, is both simpler and much harder to defeat.
Every detection is confirmed over a sustained window rather than acted on instantly, and each is logged with the time and the measured values before an alert is sent.
The log lives in non-volatile memory, so cutting the power to hide the evidence does not erase it.
This is the chapter that separates an engineering project from an assembly job. Every value below carries the formula that produced it and the assumptions it rests on — check them against your own ratings before you use them, because your motor is not this motor.
threshold must exceed the combined worst-case error of both CTs
Two class 1 CTs can each read 1 percent out, in opposite directions, and their errors grow at low current. A threshold below the combined error produces constant false alarms; this is the single most important number in the project.
the difference must persist, not merely appear
Motor inrush, switching transients and the two CTs' differing response all produce brief mismatches. Requiring persistence removes almost all false positives at the cost of a delay that does not matter for this application.
any difference between phase and neutral current has another return path
This is the same principle as an earth leakage circuit breaker. It catches a tap that returns through earth rather than through the meter's neutral, and it doubles as a genuine safety function.
R = desired peak voltage / peak secondary current
Both CTs must have identical burden resistors and identical signal chains, because the whole method depends on comparing them. Matching the two channels matters more than the absolute accuracy of either.
records x bytes per record, against the memory available
Write on an event, not continuously, or the memory's write endurance is consumed in weeks. A circular buffer that overwrites the oldest entries keeps the most recent history without ever filling up.
| Item | Qty | Unit cost |
|---|---|---|
Current transformers SCT-013-000 split core, matched pair plus one for neutral | 3 | Rs 400 to Rs 900 |
Voltage sensor module ZMPT101B, 250 V AC input | 1 | Rs 120 to Rs 260 |
Microcontroller board ESP32 with WiFi, or with a GSM module | 1 | Rs 350 to Rs 900 |
GSM module SIM800L with a 2 A supply, only if there is no WiFi Skip if you use WiFi and a web dashboard. | 1 | Rs 450 to Rs 1,100 |
Magnetic sensor Hall effect sensor or a reed switch | 1 | Rs 40 to Rs 150 |
Tamper switch Microswitch on the enclosure lid | 1 | Rs 30 to Rs 120 |
External EEPROM AT24C256 on I2C, for the event log | 1 | Rs 60 to Rs 220 |
Real-time clock DS3231 with a backup cell | 1 | Rs 120 to Rs 350 |
Burden and signal components Matched 68 ohm 1 % resistors, bias network, filtering | 1 | Rs 40 to Rs 140 |
Reference meter PZEM-004T, for calibration | 1 | Rs 600 to Rs 1,400 |
Display 16x2 LCD with I2C backpack | 1 | Rs 140 to Rs 320 |
SMPS power supply 5 V, 2 A, enclosed | 1 | Rs 180 to Rs 400 |
Enclosure and wiring Sealed ABS box, glands, terminal blocks, ferrules | 1 | Rs 350 to Rs 900 |
Test load and tap Lamp bank plus a switchable tap point for the demonstration | 1 | Rs 400 to Rs 1,200 |
Specifications are written as ratings rather than brands, so any equivalent part works. Where a line says to borrow from the lab, do — it is usually the largest number on the page, and the total drops to Rs 5,732 at the low end without them.
None of these blocks you — they are learnable inside a semester. Each one you do not have costs a couple of weeks, so count them into your plan.
Anything marked required is a blocker, not a difficulty. Arrange the access before you commit to the project, not after.
Use these when your guide says the scope is too small, or when you want something in the results chapter that nobody else in your batch will have.
The structure below is what a project report is marked against, with the mistake that costs marks in each chapter. There is no template to download and there will not be one: the writing is your work, and a site that did it for you would be helping you cheat rather than helping you pass.
A diploma report is typically 40 to 60 pages. The design and results chapters carry the marks; the literature survey can be short. A mini project report runs to about 40 to 50 pages, and the literature survey is usually brief. Guides expect one clear objective, met and measured. A final year report is normally 60 to 90 pages with a substantial literature survey, and many departments expect a paper submission alongside it.
The full report guide — front matter, conventions and page countsOne paragraph covering what the problem is, what you built, and what the result was. Written last, even though it appears first.
Loses marks: Describing the problem and the method but never stating a result. If there is no number in your abstract, it is not finished.
Why the problem matters, the context it sits in, and a clear statement of the objectives your project set out to meet.
Loses marks: Objectives written so vaguely that nobody can tell at the end whether they were met. Write objectives you can tick off in the conclusion.
What has already been done, what each approach achieved, and the specific gap your work addresses.
Loses marks: A list of paper summaries with no comparison and no gap. The survey exists to justify your design choice, so end it by saying what you chose and why.
The system as a whole: the block diagram, what each block does, and the signal or power path between them.
Loses marks: A block diagram copied from a datasheet or another report. Draw yours to match what you actually built, including the parts that are inconvenient.
Every component value and rating, with the formula, the assumptions and the arithmetic that produced it. This is the chapter that distinguishes an engineering project from an assembly job.
Loses marks: Component values with no justification. If a resistor is 10 kOhm, the report must say why it is not 1 kOhm.
The circuit as built, the PCB or wiring, the flowchart, and the parts of the code that carry the actual logic.
Loses marks: Twenty pages of pasted source listing. Include the flowchart and the few functions that matter, and put the full listing in an appendix.
What you measured, in tables and graphs, compared against what you predicted in the design chapter — including where they disagreed.
Loses marks: Photographs of the working model presented as results. A photograph is evidence that it exists, not evidence that it works. Results are measurements.
Whether each objective was met, what the measured performance was, and what the honest next step would be.
Loses marks: Future scope written as a wish list of unrelated features. It should follow from a limitation you actually hit.
Every source in a consistent style, plus datasheets, full code listings and the complete bill of materials.
Loses marks: Citing a blog or a video where a datasheet or a standard exists. Cite the primary source for anything you relied on.
The demonstration is half the assessment. These are the questions this project invites, and the answers are written the way you would give them out loud.
In a healthy circuit, all the current that flows past the upstream CT must also flow past the downstream one, because there is no other path. A tap between them draws current that passes the first CT and not the second, so the two readings diverge by exactly the stolen current. It is a conservation argument, which is why it works regardless of what the load is doing.
The combined worst-case error of the two measurement channels. Each CT has an accuracy class, and that error grows proportionally worse at low currents, so at any moment the two readings can legitimately differ by the sum of their errors. The threshold has to sit above that, or the meter reports theft every time nothing is wrong, and a detector that is ignored is no detector at all.
Because a tap that returns through earth rather than through the meter's neutral would not necessarily show up between two series CTs on the phase. Any difference between phase and neutral current means some current is returning by another route, which is the same principle an earth leakage circuit breaker uses, and it also serves as a genuine safety check.
Because the effect depends on the meter's internal design and may be subtle or absent, while the field itself is unambiguous and easy to sense. Detecting the cause also means the event is logged the moment the magnet is applied, rather than being inferred later from a suspicious drop in recorded consumption.
Because the obvious response to being detected is to cut the power. If the log lives in RAM, the evidence disappears with it. Writing events to EEPROM or FRAM as they happen means the record survives, and it is why the write strategy — on events, in a circular buffer — matters as much as the detection itself.
Anything that does not create a current imbalance between the two measurement points or a magnetic signature. A CT whose secondary has been shorted or shunted, a meter altered in firmware, a connection tapped upstream of both CTs, or an arrangement made with someone who has legitimate access. Stating those limits is part of doing the project honestly.
Normally taken as a Diploma project (C-20, 6th sem) or B.E. mini project (5th/6th sem) or B.E. final year project (7th/8th sem) project. If yours is a different course, the extensions above scope it up and the simpler half of the design scopes it down — the arithmetic does not change. Back to all projects.