Criticality depends on the consequence of failure, not appliance power. Small controls can matter more than a high-power household appliance.
Safety and comfort
Separate safety needs, essential household functions and deferrable uses. Account for the actual occupants.
Water, air and refrigeration
A well pump needs starting and water-storage assessment; ventilation needs runtime planning; refrigeration has compressor cycles. Do not multiply every nameplate rating by 24 hours without examining use.
Communications, controls and gates
Check dependencies: a router needs upstream connectivity, and gates need an accessible opening method. Low power does not mean continuity requirements are unimportant.
Heating
Identify electrical dependencies of boilers, pumps and heat pumps. Electric backup heating can exceed reserve capacity even when controls remain powered.
Power, energy and starting
Collect running power, duration and starting data. Twelve-, 24- and 72-hour scenarios may require different load lists and restrictions, not just different battery sizes.
Backup circuits and verification
An electrical professional designs critical circuits with protection and transfer arrangements. Acceptance should test actual starts and grid restoration.
| Item | Parameter | Check / result |
|---|---|---|
| Function | Failure consequence | Priority |
| Appliance | Running + starting | Inverter |
| Duration | Energy budget | Battery + recharge |
What this means for your project
Use the calculator after listing essential functions. Retain assumptions and verify them with measurements during commissioning.
Sources and scope of review
Related reading
- Private House Electrical Supply: Basic Regulatory Issues
- Home Autonomy for 12, 24 and 72 Hours
- Solar and Backup Systems: What to Check in Regulations