Volt-drop estimates by length and load.
Keep controls reliable by sizing feeders correctly. Enter cable type, length, and current to check volt-drop limits for panels, HPUs, and field devices (514–515, 347). Adjust for grouping and temperature, then export a table for drawings and ITP evidence (931, 714). This prevents nuisance faults that could compromise automatic HVM bollard performance during SAT (632–636). Include one-sentence context that naturally links upward to the parent hubs (this section and the chapter hub). Add SIRA context with a link to SIRA Bollards (UAE) when relevant. Link installation pages only if helpful: What to Expect and Installation Guide.
Important: This is a general guide. For live projects we develop a tailored
Method Statement & Risk Assessment (MS/RA) and align with authority approvals (e.g., SIRA) where in scope.
925.1 Purpose
Size cables/routes for panels and devices serving HVM bollards (515, 347).
This calculator helps you pick cable sizes and routes that maintain acceptable voltage drop from the supply to the lane’s control panel, HPU, and field devices. It supports both low-voltage control runs and three-phase feeders, keeping automatic lanes within operating tolerances to avoid brownout conditions and nuisance trips.
Use it during concept design and detailed design alongside Electrical Supply & Protection (514) and Cables & Routing (515). For enclosure entry, earthing and segregation choices, see Enclosures & Cabling (347).
| Aspect | What matters | Where to verify |
|---|---|---|
| Performance | Tested system (bollard + footing) | HVM Ratings & Compliance |
| Operations | Duty cycles, fail-state, safety | Installation Guide |
925.2 Inputs
Load, length, material, temperature, grouping, start voltage (515). Crash rated bollard peripherals included.
Enter circuit type (e.g., 3-phase feeder to HPU motor starter; 24 VDC control to photo-eyes or loop detectors), design current, route length, conductor material (Cu/Al), and installation method. Apply ambient temperature and grouping corrections so the current-carrying capacity you rely on matches field conditions.
Specify the supply/start voltage at the origin (e.g., 400/230 V AC or 24 V DC) and your allowable % drop at the load. Where EMC or segregation constraints apply, note the cable family for control vs. power as outlined in Interface Types (531) and Control Architecture (521).
925.3 Method
Applies volt-drop and derating checks; flags EMC/segregation (347, 531). Practical outputs.
The tool multiplies route length by conductor resistance/reactance to compute drop at your design current, then applies corrections for installation, ambient and grouping. It highlights routes that breach your %-drop target or where the selected CSA underperforms after derating. For control runs, it also flags circuits that risk brownout at safety devices & measures.
It surfaces EMC/segregation prompts when power and SELV/PELV controls share containment, echoing guidance in 347 — Enclosures & Cabling and 531 — Interface Types.
925.4 Outputs
Recommended cable sizes, max lengths, warnings for glands/seals (245, 334). Prevents nuisance faults.
Results include recommended CSA per circuit, maximum permissible length for your %-drop limit, and a pass/fail indicator. Where routes cross drainage features or chambers, it reminds you to match Drainage strategy (245) and use the correct cable glands and seals at entries referenced in 334 — Drainage for installations.
For HPUs and electromechanical drives, the calculator notes inrush assumptions so you can sanity-check protection settings in 514 — Electrical Supply & Protection.
925.5 Limits
Doesn’t replace protection coordination (514). Note harmonics where relevant.
The tool focuses on volt-drop suitability, not breaker sizing or discrimination. Always confirm short-circuit ratings and selectivity per 514. Where drives or switch-mode supplies are used, be aware of harmonic distortion (THD) and verify that %-drop stays within device tolerance under worst case.
925.6 Validation
Cross-check against commissioning measurements (632) and as-builts (731). Keeps HVM bollard data honest.
On site, compare predicted values against measurements during Power-On & Controls Health (632). Capture meter readings, feeder IDs and route lengths into your As-Built drawings & models (731) and the CAD/BIM standards (931) so the record set aligns with what was installed.
Use the evidence during ITP (714) checks and later SAT stages (633), (634), (635), and (636).
925.7 Ducting tie-ins
Suggest duct sizes/draw pits if needed (246, 615). Buildable runs.
Where the calculator shows larger CSAs or parallel runs, it prompts duct size and bend-radius checks so you can update Ducting & Pathways (246) and coordinate draw-pit details (615). This keeps cable pulls within allowable sidewall pressure and ensures gland plates and entries are achievable.
925.8 Save/Export
PDF/CSV with routes and IDs (911). Reviewer friendly for crash rated bollard installs.
Export CSV/PDF tables that include circuit IDs, origin/destination, route length, CSA, %-drop, and pass/fail. File names should follow the File Index & Naming Rules (911) so records slot cleanly into the calculations pack and submission sets.
925.9 Related
See enclosure/heat tools and interface types (926, 521, 531). End-to-end.
For temperature-driven drops inside enclosures, run the Enclosure Heat-Load Estimator (926). Revisit Control Architecture (521) and Interface Types (531) to confirm segregation and signaling constraints before you freeze the routes.
Related
External resources
925 Cable Volt-Drop Calculator — FAQ
What % volt-drop should I use for bollard control circuits?
For SELV/PELV control runs to safety devices & measures, many teams aim for a conservative low single-digit % drop to avoid brownout and sensor resets. Set your target based on device datasheets and verify at Power-On (632).
Does the calculator account for motor inrush at the HPU?
It highlights that inrush affects protection but keeps volt-drop based on the design steady current. Use the result with 514 — Electrical Supply & Protection to size breakers and confirm selectivity.
Can I mix power and control in the same duct?
The tool will flag EMC/segregation concerns. Follow the separation guidance in 347 — Enclosures & Cabling and 531 — Interface Types.
How do I file exports in the submission pack?
Export CSV/PDF with route IDs, CSA and %-drop, then name and place files per File Index & Naming Rules (911) and your Submission-Pack Guidance (938).