How to Choose the Right Composite CCTV Cable for Long-Distance Security Surveillance Systems

What Makes a Composite CCTV Cable Different

A composite cctv cable bundles a 75 Ω coaxial video line and a parallel pair of DC power conductors inside one jacket. Installers also call it a siamese cctv cable, a CCTV power and video cable or a coaxial power combo cable. All of these names describe the same idea: one pull delivers both picture and power to the camera. On a short run inside a shop, the convenience is obvious. On a perimeter run of 150 m or more, the construction details decide whether the camera shows a crisp picture at night or reboots every time the infrared lamps switch on.

An RG59 composite cable joins one coaxial video core and two power conductors in a single sheath.

Three Building Blocks

• Video core: a copper center conductor surrounded by foam or solid polyethylene dielectric and covered by braid and foil shielding. It carries the analog HD or standard definition signal at 75 Ω characteristic impedance.
• Power pair: two stranded or solid copper conductors, commonly 18 AWG to 22 AWG, feeding 12 V DC or 24 V AC cameras.
• Outer jacket: one PVC, PE or LSZH sheath with a thin web between the cores, so the installer can split the two sides for termination.

Distance Limits: The Specification That Decides Everything

Video attenuation grows with both frequency and length. A 1080p analog HD signal occupies far more bandwidth than a legacy 960H picture, so a cable that once reached 500 m may now deliver a clean image at roughly 300 m. The chart shows indicative planning values for 1080p analog HD over copper conductors. Always confirm them against the attenuation table in the datasheet of the cable you intend to buy.

Power usually fails before video does, which is why the shorter of the two limits always wins. Three numbers anchor most design decisions.

What Eats Into Your Signal

• Thin shielding, which lets interference in and signal out.
• Poor dielectric consistency, which causes impedance dips and ghosting.
• Low conductor purity, which raises attenuation at high frequency.
• Badly crimped connectors, which are responsible for a large share of field faults.
• High ambient temperature, which increases loss along the whole run.

Choosing the Video Core: RG59, RG6 and RG11

An RG59 composite cable remains the default for most commercial projects because it is flexible, easy to terminate and inexpensive per meter. It handles typical building runs without trouble. When the distance stretches, a larger center conductor and thicker dielectric reduce loss, which is the reason RG6 and RG11 versions exist.

When RG59 Is Enough

If every camera sits within 250 m of the recorder, an RG59 core is usually the sensible choice. It leaves a margin of around 15 to 20 percent for connectors, patch points and aging.

When to Step Up

• Runs beyond 300 m for 1080p or higher bandwidth formats.
• Routes that pass through splices or several junction boxes.
• Sites with strong electrical noise, such as substations or workshops.

Keep in mind that larger coax is stiffer. A minimum bend radius of about ten times the cable diameter is a safe rule, and RG11 cables need wider pulling corners and larger junction boxes.

Sizing the Power Pair and Controlling Voltage Drop

Current travels out to the camera and back again, so the electrical loop is twice the cable length. Resistance in that loop turns into lost voltage, and the camera sees whatever remains. Typical copper resistance is about 21 Ω per kilometer for 18 AWG, 33 Ω for 20 AWG and 53 Ω for 22 AWG.

The result is sobering. At 100 m, a 22 AWG pair already loses more than a quarter of a 12 V supply, while an 18 AWG pair stays near 10 percent. Infrared lamps, heaters and motorized lenses raise the current further, so a camera that works at noon can fail at night.

Practical Ways to Stay Inside the Limit

1. Choose a thicker power pair, since each step down in gauge number lowers loss noticeably.
2. Move to 24 V AC or another higher supply voltage, which cuts current for the same power.
3. Place a local power supply near a group of distant cameras instead of powering all from the recorder room.
4. Leave a design margin for connectors, temperature and future camera upgrades.

Conductor Material: Why Copper Purity Matters

Two cables with the same printed gauge can behave very differently. Copper-clad aluminum carries a thin copper skin over an aluminum core, and its direct current resistance is substantially higher than that of solid copper. The chart compares relative resistance for the same diameter.

Higher resistance means more heat and more voltage drop, and the aluminum core is also more brittle. It can crack when bent repeatedly and corrodes faster at terminals. Several project specifications therefore require pure copper power conductors, and reputable suppliers state the material openly on the datasheet.

Simple Field Checks

• Scrape the end of a conductor: a silver-gray core under the copper layer indicates aluminum.
• Compare the measured loop resistance of a 100 m sample against the datasheet value.
• Weigh a one-meter piece, because aluminum is far lighter than copper.

Composite Cable Compared with Other Cabling Approaches

A combined cable is not the answer to every layout. The radar chart rates three common approaches on five practical criteria using a one to five scale. The scores are indicative and reflect typical analog HD projects.

How to Read the Comparison

RG59 composite wins on installation speed because one pull replaces two, and many crews report noticeably shorter pulling time per camera. RG6 composite stretches the distance and signal quality but costs more and bends less easily. Separate cables remain the most flexible, since power and video can be routed independently, but they double the pulling, labeling and termination work.

For most multi-camera sites, the practical answer is mixed: use RG59 composite for the many short and medium drops, and reserve RG6 or separate runs for the few remote cameras.

Jacket, Shielding and Environmental Protection

The jacket decides how long the cable survives outdoors. Sunlight, moisture, rodents and temperature swings attack the sheath long before they touch the copper.

Shielding Basics

A foil layer blocks high-frequency noise, while braid gives low-frequency protection and mechanical strength. A braid coverage of 90 percent or more combined with foil is a solid baseline for sites near motors, lifts and radio equipment. For aerial spans, add a steel messenger wire; for wet ground, ask for a water-blocking layer.

A Step-by-Step Selection Workflow

The flowchart turns the earlier sections into a repeatable routine that can be reused for every project.

Worked Example

Consider a perimeter with twelve cameras, the farthest sitting 220 m from the equipment room. Each camera is rated 24 V AC and draws 0.25 A.

• Video: 220 m is inside the 300 m RG59 limit with a margin of about 27 percent, so an RG59 core is acceptable.
• Power on 24 V AC: an 18 AWG copper pair has a loop resistance near 9 Ω, giving a drop of about 2.3 V, or roughly 10 percent.
• Power on 12 V DC: the same load would lose the same 2.3 V, nearly 19 percent of the supply, and the camera would fail.

The sensible specification is an RG59 composite cable with a copper 18 AWG power pair, a UV-stabilized PE jacket, and a 24 V AC supply.

Qualifying a Security Camera Wire Manufacturer

Good paperwork separates a dependable security camera wire manufacturer from a trader who simply relabels reels. The first purchase should be treated as a technical audit, not a price negotiation.

Questions to Ask Before Ordering

• Which conductor material is used in the video core and the power pair, and can a test report prove it?
• What are the measured attenuation values at several frequencies, and over which length?
• What is the direct current resistance per kilometer for each conductor?
• Which jacket compounds are available, and do they carry environmental compliance reports?
• How is reel length tolerance controlled, and how are reels packed for shipping?

A Simple Sample Test Plan

1. Measure the physical diameter of every layer and compare it with the datasheet.
2. Test loop resistance on a 100 m sample at room temperature.
3. Terminate the coax and check return loss with a cable analyzer.
4. Bend the cable repeatedly at its rated radius and inspect for cracks.
5. Run a live 1080p camera on the longest planned length for 24 hours.

Keep the sample results on file. They become your benchmark for incoming batches and a reference if a warranty question appears later.

Installation, Termination and Testing for Long Runs

Even a well specified cable underperforms when the installation is careless. On long runs, small mistakes add up: a kinked section here, a poor crimp there, and the margin you designed is gone before the first camera is powered.

Pulling and Routing Practices

• Respect the pulling tension on the datasheet, because stretching the coax changes the dielectric spacing and permanently alters impedance.
• Keep the cable at least 30 cm from mains wiring, or cross it at a right angle, to limit induced noise.
• Use a lubricant approved for the jacket material when pulling through long conduit.
• Leave a service loop of one to two meters at each camera and at the recorder.
• Label both ends of every run before pulling, not afterwards.

Termination Quality

Connectors are the weakest point of any coaxial link. A compression connector sized for the exact cable outline keeps the shield continuous and holds impedance steady. Twist-on and soldered joints are far more variable, and field surveys often trace the majority of picture faults to the connector rather than the cable itself.

On the power side, avoid wire nuts and loose screw terminals. Use crimped ferrules or sealed connectors, and apply anti-oxidation treatment where the pair meets a terminal block outdoors. A single high-resistance joint can add the same loss as another fifty meters of cable.

Commissioning Checks

1. Verify continuity and polarity of the power pair before connecting any camera.
2. Measure supply voltage at the camera end under full load, with infrared lamps switched on.
3. Confirm the video picture is free from ghosting, rolling bars and color smear at both day and night settings.
4. Record measured values for every run in a simple table, then store it with the as-built drawings.

Protecting the System from Surges

Long outdoor cables act like antennas for lightning and switching surges. Install video and power surge protectors at both ends of any run that leaves the building, and bond the shield to a clean earth point at a single location to prevent ground loops. In exposed areas, keep the cable inside metallic conduit or buried below the frost line, and separate it from any lightning down conductors.

Planning for Future Upgrades

Camera resolution tends to rise every few years. A cable that carries 1080p comfortably today may be stretched by a higher bandwidth format tomorrow. When the budget allows, specify one grade above the current requirement, such as RG6 where RG59 would just meet the distance. The extra material cost is small compared with the labor of pulling new cable through finished walls and trenches.

Also leave spare capacity in the power budget. A recorder room supply sized exactly for today's cameras leaves no room for heaters, wipers or additional lamps. A margin of 25 percent on total current is a practical target, and it protects the supply from running hot during summer peaks.

Frequently Asked Questions