RG59 Siamese Cable with Power — 300 Metre Reel
The RG59 Siamese Cable with Power (300 metre reel) is a combined coaxial and power cable for analogue and HD-over-coax CCTV camera installations. It integrates an RG59 75-ohm coaxial core for video transmission with a parallel 2-core power conductor in a single bonded jacket — removing the need to pull separate video and power cables to each camera position. The 300-metre reel extends the single-spool coverage of the 200-metre variant, making it better suited to larger installations, campus deployments, and multi-building security projects where longer individual camera runs or higher camera counts are required.
This cable is compatible with analogue CVBS, HD-CVI, HD-TVI, and AHD camera systems, and connects directly to BNC-input DVRs and camera heads without active conversion hardware.
Video Transmission — RG59 Coaxial Core
The RG59 coaxial core maintains a characteristic impedance of 75 ohms — the standard for video signal transmission. This impedance match between cable, camera output, and DVR input minimises signal reflection across the run, preserving video quality from camera head to recorder.
RG59 supports both standard definition analogue video (CVBS) and HD-over-coax formats including HD-CVI, HD-TVI, and AHD at resolutions up to 4K (8MP) on appropriate run lengths. Consequently, installations using this cable are not locked into legacy analogue resolution — camera head replacements can deliver HD or 4K video over the existing RG59 infrastructure without recabling. This forward compatibility is a material cost benefit on large installations where cabling labour represents a significant share of project value.
Recommended maximum transmission distances by format:
- Analogue CVBS — Up to 300 metres
- HD-CVI / HD-TVI / AHD (1080p) — Up to 500 metres (format and DVR dependent)
- HD-CVI / HD-TVI / AHD (4K/8MP) — Up to 150–200 metres (format dependent)
The centre conductor is typically 20 AWG copper-clad steel (CCS) or bare copper. Bare copper provides lower DC resistance per metre — directly relevant on runs approaching the maximum transmission distance or where the power core must supply higher-current camera loads at the far end of the reel.
Power Core
The integrated power core runs two 18 AWG conductors — positive and negative — parallel to the coaxial core within the shared outer jacket. This pair delivers DC or AC power from a centralised CCTV PSU or individual adapters to cameras along each run.
At 300 metres per reel, power core voltage drop calculation is particularly important. Longer individual camera runs increase resistive voltage drop along the 18 AWG conductors. Cameras receiving below their minimum rated input voltage exhibit symptoms including image instability, IR cut-filter failure, and inability to initialise. On runs exceeding 30–40 metres with 12V DC cameras drawing 300–500mA, a higher voltage PSU output or a step-up to 24V AC supply should be considered to compensate for drop.
For the power core specifically, bare copper conductors offer materially lower resistance per metre compared to CCS — making conductor material confirmation a priority before deploying this cable on long camera runs.
Cable Construction
The RG59 Siamese Cable bonds two parallel components within a shared PVC outer jacket:
Coaxial component:
- Centre conductor: 20 AWG (CCS or bare copper)
- Dielectric: Foam or solid polyethylene
- Shield: Aluminium foil with braided copper or aluminium coverage
- Impedance: 75 ohms
Power component:
- Conductors: 2 × 18 AWG (CCS or bare copper)
- Insulation: PVC, colour-coded (typically black and white, or red and black)
The siamese profile allows the installer to split and peel back the coaxial and power sections at each termination point. This separation occurs cleanly along the bond line without cutting into either core, simplifying BNC termination at the camera head and DC connector attachment at the PSU end.
Installation Characteristics
The 300-metre reel covers larger installation volumes than the 200-metre variant — typically 10–15 cameras per reel depending on average run length, or fewer cameras on sites with long individual runs from a centralised head-end to perimeter camera positions. The additional reel length reduces the number of mid-project reel changes on large sites, improving installation efficiency.
At each camera end, the coaxial core terminates with a BNC connector — compression-fit or crimp-type — connecting directly to the camera video input. The power core terminates into a DC barrel connector (typically 5.5mm × 2.1mm) at the camera and connects to the PSU output at the head-end.
On longer runs characteristic of 300-metre reel deployments, cable routing discipline is more critical. Parallel runs alongside mains AC cabling increase electromagnetic interference exposure on the coaxial core. Where crossings with AC cabling are unavoidable, routing at 90 degrees minimises interference coupling — a common cause of hum bars and banding artefacts on analogue and HD-over-coax video feeds.
Supported Applications
The RG59 Siamese Cable with Power (300 metre) supports the following installations:
- Analogue CCTV (CVBS) — Standard definition DVR-based systems up to 300m per run
- HD-CVI — Dahua and Hikvision HD-over-coax at 2MP, 4MP, and 8MP
- HD-TVI — Turbo HD over coax at 2MP, 4MP, and 4K
- AHD — Analogue High Definition over coax
- IR Bullet and Dome Cameras — Fixed analogue and HD-over-coax cameras with integrated IR
- PTZ Cameras — 12V DC and 24V AC pan-tilt-zoom installations (voltage drop calculation required)
- Large-Site and Campus DVR Systems — 8, 16, and 32-channel DVR deployments with extended perimeter runs
- Multi-Building Installations — Car parks, warehouses, industrial estates, and education campuses
Ideal Users
- CCTV and Security System Installers on Large Commercial Sites — The 300-metre reel is matched to installations where individual camera runs regularly exceed 20–30 metres and total cabling volume per project makes the 200-metre reel inefficient. Fewer reel changes and joins on long perimeter runs reduce installation time and the number of potential signal integrity failure points.
- Systems Integrators Serving Industrial and Warehouse Clients — Large footprint sites — distribution centres, manufacturing facilities, and logistics yards — require extended cable runs from perimeter and internal camera positions to a centralised DVR head-end. The 300-metre reel provides the per-reel capacity to handle these runs without mid-cable joins.
- Property Developers Pre-Wiring Large Residential and Mixed-Use Schemes — Pre-installing RG59 Siamese during construction across multi-unit residential blocks, car parks, and communal areas provides a ready-to-activate CCTV infrastructure. HD-over-coax compatibility means the pre-installed cable supports future resolution upgrades without infrastructure replacement.
- Legacy Analogue System Upgraders — Where sites have existing RG59 infrastructure from legacy analogue installations, the cable’s HD-CVI, HD-TVI, and AHD compatibility enables camera head replacement to deliver HD resolution over the same cable plant. The 300-metre reel is suited to sites where the original installation used longer runs typical of larger perimeter coverage areas.
- Education, Healthcare, and Local Authority Estate Teams — For multi-building campuses where IP network infrastructure does not extend to all camera locations, RG59 Siamese provides a self-contained video and power solution operating independently of the data network. The 300-metre reel capacity handles the extended runs between buildings and across open grounds typical of these sites.
Coaxial Core Specifications
| Attribute | Detail |
|---|---|
| Cable Type | RG59 |
| Impedance | 75 ohms |
| Centre Conductor | 20 AWG CCS or Bare Copper |
| Dielectric | Foam or Solid Polyethylene |
| Shield | Aluminium Foil + Braided Coverage |
| Connector Type | BNC (compression or crimp) |
Power Core Specifications
| Attribute | Detail |
|---|---|
| Conductors | 2 × 18 AWG |
| Conductor Material | CCS or Bare Copper |
| Insulation | PVC, colour-coded |
| Supported Voltage | 12V DC / 24V AC |
| Connector Type | DC Barrel (5.5mm × 2.1mm) |
Transmission Distance Reference
| Format | Max Recommended Distance |
|---|---|
| Analogue CVBS | Up to 300m |
| HD-CVI / HD-TVI / AHD (1080p) | Up to 500m (format dependent) |
| HD-CVI / HD-TVI / AHD (4K/8MP) | Up to 150–200m (format dependent) |
Physical Specifications
| Attribute | Detail |
|---|---|
| Reel Length | 300 metres |
| Outer Jacket | PVC |
| Jacket Colour | Black or Grey (varies by batch) |
| Outer Diameter (approx.) | 9.0–10.0mm (siamese profile) |
| Operating Temperature | -20°C to +60°C |
| Installation Temperature | 0°C to +50°C |
Installation Parameters
| Attribute | Detail |
|---|---|
| Minimum Bend Radius | 50mm |
| Recommended PSU Output | 12V DC regulated multi-output CCTV PSU |
| Power Run Limit (12V DC, 500mA) | Approx. 30–40m (verify via voltage drop calculation) |
| Long Run Power Recommendation | 24V AC supply for runs exceeding 40m |
| AC Interference Mitigation | Route at 90° to mains cabling where crossings required |
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