514.1 Feeders & breakers

Size feeders by demand and fault level; use coordination curves. Correct sizing protects HVM bollard panels.

Start with the connected load and diversity (utility profile & sources). For HVM lanes, include inrush for motors/HPUs and any EFO loads. Select cable size from volt-drop and thermal limits, then choose breaker frames/curves to protect the feeder and terminations.

Verify feeder fault withstand versus prospective short-circuit current at the panel incomer (see 514.4). For long runs, calculate voltage drop with the Cable Volt-Drop Calculator (925). Where multiple lanes/arrays share a source, provide segregated feeders to avoid common-mode trips.

514.2 RCD/RCBO policies

Apply RCDs where personnel risk exists; avoid nuisance trips for drives. Balanced policy preserves crash rated bollard reliability.

Use RCD/RCBOs for socket outlets and maintenance circuits where personnel contact is plausible. For crash-rated lane power, avoid upstream RCDs on inverter/drive and HPU motor feeders to reduce nuisance tripping—prefer equipment-integrated protection and insulation monitoring where needed. For outdoor circuits, specify Type A/Type B devices as appropriate to the drive topology.

Document the policy in the FDS and show it on the Single-Line Diagram (SLD). Where authorities require personnel protection, dedicate a downstream RCD/RCBO per outlet group to preserve selectivity.

514.3 Isolation & lockout points

Provide local isolators and clear LOTO procedures (725). Safe isolation protects HVM bollard maintenance.

Fit lockable local isolators at each lane panel and at field equipment enclosures to support LOTO. Mark “Test/Isolate” positions on control power where applicable, and show zero-energy boundaries in the MS/RA and LOTO plan (725).

Provide visible indication of isolation (e.g., door interlocks, “door-open tamper” on panels) and a recovery checklist in the handover pack so the system returns to a safe local mode after work. Coordinate with Enclosures & Cabling (347) for IP/IK ratings.

514.4 Short-circuit levels

Verify device Icu/Ics vs fault currents. Adequacy keeps crash rated bollard circuits safe.

Calculate prospective short-circuit current at each protective device (utility transformer data + impedance of feeders). Ensure device interrupting capacity (Icu/Ics) exceeds the calculated value with margin. For panels fed by generators or UPS with ATS/STS, check both utility and source-limited fault levels.

Record calculations and device datasheets in the ITP (714) and commissioning pack. If fault level exceeds device ratings, re-engineer the feeder, move the protective device upstream, or use current-limiting fuses.

514.5 Protection coordination

Grade breakers/fuses to trip selectively. Coordination keeps other HVM bollard lanes alive during faults.

Build a simple grading study: upstream vs downstream trip curves and time delays, including any fuses on motor starters. The aim is selective tripping so a fault in one lane does not black out adjacent lanes or control systems. Where absolute selectivity is not feasible, target partial selectivity for fault magnitudes typical of the load.

Document settings (LSI, earth-fault, RCD) and store the curves with the panel wiring standards (527). Re-verify selectivity after any change control (see 537).

514.6 Harmonics & power quality

Assess THD and apply filters if needed. Clean power protects crash rated bollard electronics (511).

Variable-speed drives and switch-mode supplies inject harmonics. Measure or estimate THD and voltage flicker during typical duty and EFO scenarios. If limits are exceeded, add line reactors, passive/active filters, or increase feeder stiffness. Protect control electronics with surge protection (see 514.9) and clean power practices from Supply & Sources (511).

For long outdoor runs, consider brownout/ride-through (ride-through) and specify autonomy for any UPS that supports controls/communications.

514.7 Labeling & identification

Adopt consistent panel/circuit labels (527, 347). Labels reduce HVM bollard errors.

Use durable engraved labels and printed ferrules matching the lane identifier and circuit function (e.g., “LN-02: HPU MOTOR F1”). Follow Panel Wiring Standards (527) and Enclosures & Cabling (347). Include hazard stickers for arc-flash/shock where applicable and a laminated SLD in each door card.

Consistent identification speeds fault-finding and supports remote fault logging and operational dashboards.

514.8 Test certificates

Compile IR/continuity, earth, and functional tests (631–632). Certificates support crash rated bollard submittals (444).

Before energization, record insulation resistance and continuity for all feeders and field circuits. After power-on, capture earth-fault loop impedance and RCD trip tests, then complete controls health checks (632) and functional tests (636). File signed certificates inside the evidence & documentation pack and include a copy in the submission pack (938).

514.9 Compliance references

List the governing codes/standards used. References speed HVM bollard approvals (938).

Declare the earthing system (e.g., TN/TT), specify SPD classes and locations, and cite national wiring rules followed for the project. Summarize any utility/authority addenda and attach acceptance emails in the submission index. Note: where approvals in Dubai apply, include a short SIRA note and link to the SIRA hub.

514 Electrical Supply & Protection — FAQ