Calculator · Access control
Access control door power supply calculator
Enter the locks, readers and controllers on the supply and the current each one draws, from its data sheet. You get the total load, the supply rating to choose, and how long a battery of a given size will last.
Result
Enter at least one group to see the result.
Working
supply rating = total load × (1 + headroom)
- Total load is the sum of (number × current) for every group, in amps.
- Supply rating is the total load plus headroom. The headroom is your choice.
- Standby time on a battery is the battery amp hours divided by the total load in amps.
Source: the Paxton application note AN1043 for the supply and standby rules. Paxton adds 10%, which is the smallest allowance found. SDC says to add 30%, and a UK installer's guide keeps the load to 70 to 80% of the supply's rating instead. Paxton's standby formula ignores battery ageing. Use the figures on the supply's data sheet.
To check the voltage at the lock at the end of its cable, use the lock cable calculator.
For guidance only. Always check against the current edition of the standard and the manufacturer's data.
Built by the engineer behind Kerova, certificate software for fire and security firms.