Overload
APC UPS
Severity:What Does This Error Mean?
An APC UPS Overload warning means the total power draw of all connected devices exceeds the VA (volt-ampere) or watt rating of the UPS. The UPS will alarm and may shut off output to protect itself. The immediate fix is to disconnect high-draw devices such as laser printers, heaters, or additional monitors until the alarm clears.
Affected Models
- APC Back-UPS series (BE, BX, BVX)
- APC Back-UPS Pro series (BR, BN)
- APC Smart-UPS series (SUA, SMT)
- APC Easy-UPS series
Common Causes
- Too many devices plugged in — total watt draw exceeds the UPS rated output
- A laser printer or large monitor added to the UPS — laser printers draw very high surge current
- A device with a high startup inrush current (power tools, large motors) briefly overloading the UPS
- UPS capacity chosen too small for the actual equipment load
- Internal UPS fault causing the overload detection to trigger incorrectly
How to Fix It
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Immediately unplug high-draw devices from the UPS. Laser printers are the most common culprit — they draw up to 1,000 watts when heating the fuser roller.
Laser printers should be plugged directly into the wall, not into a UPS. Connect only the computer, monitor, and network equipment to the UPS battery outlets.
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Check the total watt load of all connected devices against the UPS watt rating (printed on the label). The total must stay below 60–70% of the rated output for reliable operation.
A 1,000 VA UPS typically provides around 600 watts of real power. Add up the watt ratings of all connected devices to verify you are within limits.
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If the load is within the UPS rating and the alarm still fires, disconnect all devices and reconnect them one at a time to identify which device triggers the overload.
A faulty device with a shorted power supply can draw far more current than its label suggests. Isolating the fault this way identifies the problem device quickly.
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If no single device causes the overload and the total load is within spec, the UPS may have an internal fault. Contact APC support or replace the unit.
APC offers a warranty replacement program and a trade-in scheme for older units. A UPS that alarms falsely on a light load is no longer reliable.
Frequently Asked Questions
Will an APC UPS shut off automatically during an overload?
Yes — most APC models will shut off the output after a brief warning period if the overload is not resolved. This protects the UPS from overheating and damage. The unit beeps continuously and the overload LED lights before shutdown.