This article explains what standby power is, why some field meters can over-report it, and how to measure it correctly. It also outlines the steps we take to validate results, including an optional paid on-site verification using a calibrated (NATA-traceable) standby power meter.
Applies to
Fujitsu General residential split systems and VRF indoor units operating on mains power
Queries regarding “high standby consumption” when the system is not actively heating or cooling
Key concepts
1) Multiple standby states
Most inverter air conditioners exhibit more than one standby state:
Cooling standby: control electronics powered, system ready to cool.
Heating standby: control electronics powered, system ready to heat.
Pre-heating/low-ambient standby: an elevated standby state that may enable crankcase or electronic pre-heat functions in cold conditions. This state only occurs when ambient temperature is low and will not be present at normal room temperatures.
Actual wattage varies by model, operating mode, and ambient temperature.
2) Why some meters over-report standby
Clamp-style energy meters (current-transformer “CT” clamps at the switchboard) typically report apparent power derived from current, not true active power.
In standby, the air conditioner’s power factor is low and non-linear.
CT-only meters can show 0.5–1.0 A at the main incomer with multiple appliances in standby and convert that to watts, overstating the true standby figure.
These meters are accurate for running loads, but are not reliable for low, reactive/standby loads.
3) Correct way to measure standby
To obtain an accurate figure you must use a calibrated meter capable of measuring active power at low power factor, wired in series with the appliance (socket or circuit). This measures true (effective) power rather than estimating from current alone.
What we need from you
Please confirm:
Meter type you are using (e.g., CT clamp at the board, plug-in inline power meter, utility smart meter).
How you derived watts (direct reading vs. converting amps to watts).
Ambient temperature when the reading was taken (to assess the likelihood of a pre-heating standby state).
Whether the outdoor unit was in a cold environment (e.g., garage, balcony in winter).
With this information we can assess whether your reading reflects a true pre-heat standby condition or a measurement artefact.
Our verification process
Remote check (no charge):
Review your meter type, method, and conditions.
Advise whether the reading is consistent with typical standby behaviour.
On-site verification (optional, fee applies):
We can arrange a technician to test with a NATA-approved standby power meter, connected in series with the appliance.
You will see the true active standby power recorded under controlled conditions.
From this, we can determine whether there is a product issue or a measurement issue.
Note: The on-site verification is not covered by warranty. Our service team will provide a quotation before scheduling.
Compliance note
Standby power contributes to the product efficiency metrics used in MEPS / AS/NZS 3823.2 compliance (e.g., AEER/ACOP calculations). Products are tested against these requirements; field measurements that differ materially are commonly due to metering method or ambient conditions rather than abnormal operation.
Summary — quick checklist
Seeing unexpectedly high “standby” on a clamp meter is usually a measurement artefact.
Pre-heating standby only occurs in low ambient conditions and is higher than normal standby.
For definitive results, use a calibrated, inline meter that measures true active power at low PF.
Share your meter type, method, and conditions with us; if needed, we can arrange a paid on-site verification.