Voltage Drop Calculator
Estimate low-voltage DC voltage drop for locks, maglocks, sirens, strobes, cameras and remote equipment.
Where this matters most
| Device | Why voltage drop matters | What to check |
|---|---|---|
| Electric strike | Unlock current may be sensitive on long cable runs. | Voltage at the strike during operation. |
| Maglock | Continuous current can expose poor cabling choices. | Steady-state voltage and release devices. |
| Strobe / beacon | Long DC runs can lose too much voltage. | Load current, cable size and path length. |
Practical warning: If you are close to the limit, design it out early with thicker cable, shorter routes or local power.
How to get the most value from this page
- Use this page with the relevant calculator, template, planning pack or quote brief.
- Save or print any generated output before changing inputs.
- Check all assumptions against actual device manuals and the real site layout.
- Update the as-built documentation after installation or troubleshooting.
Important: This calculator is for early planning only. Check the actual product manuals, cable data, device wattage and site conditions before buying equipment or installing.
Voltage drop inputs
Notes
The calculation uses a two-conductor circuit length, so the conductor path is doubled. Use manufacturer cable data for accurate results.
This is especially useful for electric strikes, maglocks, sirens, strobes and remote DC loads.
Practical use cases
This page is useful for electric strikes, maglocks, sirens, strobes and remote DC-powered equipment.
| Use case | Planning note |
|---|---|
| Electric strike | Check voltage at the strike during unlock |
| Maglock | Continuous current makes voltage drop important |
| Outdoor beacon/strobe | Long low-voltage runs can drop too much voltage |
Important: Treat calculator results as planning estimates. Confirm actual product manuals and site conditions before installation.
Related resources
Calculator FAQs
Is this a final design?
No. It is an estimate for planning and product shortlisting.
Should I allow spare capacity?
Yes. Spare capacity helps with future expansion and real-world variations.