Meter Reading
Domain 7: Meter Reading
This domain tests accurate reading of mechanical and electronic displays, multipliers, time-of-day registers and rollover.
Core rules
- Record meter number, date, time, display register and multiplier.
- For a direct meter, units consumed = current reading minus previous reading.
- For a CT or PT meter, multiply the register difference by the CT ratio and PT ratio.
- Electronic meters may cycle displays for kWh, kvarh, kVAh, maximum demand and date/time; note the register code.
- Leading zeros count; after rollover, add the full meter capacity.
Worked example
Previous reading 04567 and current reading 05123 give a difference of 556. With a 200/5 CT ratio of 40 and no PT, billed energy = 556 × 40 = 22,240 kWh. If the CT is 100/5, ratio 20, the same difference gives 11,120 kWh. Reasoning: subtract readings on the same register first, then apply the correct multiplier once.
Traps that cost marks
- Subtracting readings from different registers.
- Applying the CT ratio twice.
- Ignoring leading zeros.
- Missing a rollover from 99999 to 00000.
- Treating an estimated reading as actual without marking it.