1. Common Issues in Design and Construction Phases
Common issues in design phase: Insufficient spacing between ELV and LV cable trays—parallel spacing must be ≥300mm and crossing spacing ≥100mm to prevent signal interference; insufficient equipment room area reserved, making later equipment expansion difficult; failure to reserve UPS power capacity, resulting in no redundant power supply for subsequently added equipment; cable tray fill rate exceeding 40%, affecting heat dissipation and future cabling; unreasonable VLAN partitioning leading to broadcast storms. Common issues in construction phase: Cable binding too tight, causing NEXT performance degradation; termination untwisting length greater than 13mm, causing crosstalk to exceed limits.
2. Common Issues in Communication and Control
Common communication issues: BACnet MS/TP bus communication interruption—check whether bus bias resistors and termination resistors are correctly configured, with 2 × 120Ω termination resistors required per segment, and whether the number of bus devices exceeds 32; RS485 communication instability—check whether A/B wires are reversed, whether common-mode voltage exceeds the -7V to +12V range, and whether shielded grounding is missing; TCP/IP communication packet loss—check for network loops, VLAN configuration, STP status, and port speed negotiation.
3. Common Issues in Security and Access Control Systems
Common security system issues: Excessive noise in nighttime images—add fill lights or replace with low-illuminance cameras (0.001Lux); video stream stuttering—check network bandwidth (each 5-megapixel camera stream is approximately 6–8Mbps), NVR decoding capability, and switch backplane bandwidth; insufficient video recording storage duration—adjust encoding parameters (H.265+ encoding can save 50% storage space) or add hard drives. Access control system issues: Short proximity card reading distance—check reader supply voltage, which must be 12VDC ±10%; electric lock failing to engage—check lock power supply wattage.
4. Common Issues in Integration and O&M Phases
Common system integration issues: Incompatible protocols between systems from different vendors—protocol gateways or OPC Server conversion required; data acquisition latency—excessively long polling cycles or too many points causing packet loss; inconsistency between integration platform interface data and subsystem data—refresh mechanism or caching issues; linkage logic failure—incorrect configuration of fire safety and security linkage conditions or interrupted signal transmission. O&M phase issues: Old DDC controller battery depletion causing program loss—replace motherboard battery and check periodically; UPS battery aging causing insufficient backup time—battery life is 3–5 years and requires replacement.