Analogue Wiring — Coax, Shotgun & POC

Purpose

This document covers everything you need to know about cabling for analogue HD-TVI CCTV systems. It explains the different cable types, when to use each, how to terminate them correctly, cable run limits, and the most common mistakes made on the job.

Analogue HD systems use coaxial cable to carry the video signal from each camera back to the DVR. Depending on the system type and how it's powered, the cable used varies. Understanding the difference is essential before you start pulling cable on any CCTV job.

The Three Cable Types

1. RG59 Coax

What it is: Standard 75-ohm coaxial cable. The industry-standard cable for analogue CCTV.

Construction:

• Central copper conductor (typically 20 AWG solid copper)
• Foam polyethylene dielectric (insulator)
• Aluminium foil screen
• Braided copper or aluminium outer shield
• PVC outer jacket

When to use it:

• POC systems — all power comes via the coax, so no separate power core is needed
• Any run where power is supplied locally at the camera (via a 12V DC adaptor in the camera housing)
• Where you want the slimmest, lightest cable — easiest to route through conduit and tight spaces

What it carries: Video signal only. On POC systems it also carries 12V DC power, but this is managed by the DVR and camera — the cable itself is just standard RG59.

2. Shotgun Cable

What it is: A twin-core cable where a coax core and a two-core power cable are bonded together side by side.

Construction:

• One RG59 coax core (75 ohm, video signal)
• One 2-core power cable bonded alongside (typically 2 × 0.5mm² or 2 × 0.75mm²)

When to use it:

• Non-POC systems where each camera needs its own 12V DC power feed
• Systems using a central PSU with individual power feeds running to each camera
• Where you prefer to run a single combined cable rather than two separate cables

Colour coding (power cores): Typically red (+12V) and black (0V / ground). Always confirm with a meter before connecting.

Termination at the camera end:

• BNC connector on the coax core → camera video input
• Bare wire or DC jack on the power cores → camera power input (centre positive)

Termination at the DVR end:

• BNC connector on the coax core → DVR video input
• Power cores → PSU output terminals or DC pigtail harness

3. POC-Specific Cable

There is no special "POC cable" — POC systems use standard RG59 coax. The difference is in the DVR and cameras, not the cable.

What matters: Cable quality. POC pushes 12V DC down the coax alongside the HD video signal. Voltage drop over long runs is the primary concern. Always use good quality RG59 with a solid copper centre conductor.

Cable Run Limits

HD-TVI Video Signal

Keep runs under these limits. Signal quality also depends on connectors — a poorly terminated BNC will cause problems regardless of run length.

POC Power

POC has an additional constraint: voltage drop. As current travels down the coax, resistance causes the voltage to drop. If the voltage at the camera drops too low, the camera won't power on or drops in and out.

If you need to run beyond these distances on a POC system:

• Use RG6 cable (lower resistance, larger conductor)
• Or use a local 12V DC supply at the camera and switch to standard HD-TVI (no POC)

BNC Connectors

All analogue CCTV coax is terminated with BNC connectors. BNC is the industry-standard connector for coaxial video cable and is the input/output type on all DVRs and HD-TVI cameras.

Types of BNC Connector

Crimp BNC:

• Requires a crimping tool
• The most common type used on site
• Good quality connection when done correctly
• Must be sized for your cable — RG59 and RG6 use different crimp sizes

Compression BNC:

• Requires a compression tool
• Better weather resistance — suitable for outdoor junction boxes and external connections
• Preferred for any external termination point

Twist-on / Screw-on BNC:

• No tools required
• Acceptable for temporary connections and testing only
• Do not use on a finished install — they work loose over time and cause intermittent faults

How to Terminate RG59 with a Crimp BNC

Tools needed

• BNC crimp connector (sized for RG59)
• Coax stripping tool (two-stage stripper)
• Coax crimping tool (with BNC die)

Steps

1. Strip the outer jacket — use the outer blade of the stripping tool. Remove 15–20mm of outer jacket. Do not nick the braid.

2. Fold back the braid — push the braid back over the jacket so it folds outward. Straighten any stray braid wires.

3. Strip the dielectric — use the inner blade of the stripping tool. Remove 8–10mm of the foam dielectric to expose the centre conductor. Do not nick the centre conductor.

4. Inspect — the centre conductor should be clean and straight. No strands of braid should be touching the centre conductor. This is the most common cause of a short-circuit.

5. Fit the BNC body — slide the crimp ferrule (metal ring) onto the cable first, then push the BNC body onto the cable. The centre conductor should protrude through the pin in the centre of the BNC. Push firmly until the body seats against the dielectric.

6. Crimp the pin — use the pin die on the crimping tool to crimp the centre pin onto the conductor.

7. Crimp the ferrule — slide the ferrule up to meet the BNC body and crimp with the ferrule die. This locks the connector to the cable and makes the outer connection.

8. Test — use a continuity meter to confirm: centre to centre = continuity, centre to outer = open circuit (no short). Any short between centre and outer = faulty termination, redo it.

Power Wiring for Non-POC Systems

On non-POC systems, each camera needs 12V DC. There are two approaches:

Option A — Individual PSU per camera

A 12V DC adaptor is fitted near each camera. Power is taken from a local 230V socket or spur.

• Simple and independent — one camera's power has no effect on others
• More 230V work — each location needs a power source
• More components to fail

Option B — Central multi-output PSU

A multi-output 12V DC PSU (4, 8, or 16 channel) is installed at the DVR head-end. Individual 12V feeds run to each camera via the shotgun cable power cores.

• Cleaner install — all power management in one place
• Easier to fault-find
• If the PSU fails, all cameras on it fail simultaneously
• Voltage drop must be considered on long runs

Voltage drop on power cores

Cameras need a minimum of ~10.5V DC to operate. Use the following as a guide:

Routing & Installation Practice

Planning the run

• Identify the DVR location first — all cables home here
• Walk each camera position and plan the route (loft, cavity, conduit, trunking)
• Avoid routing alongside 230V mains cables — electrical interference can affect image quality
• Leave a service loop at both ends — 0.5–1m at the camera, 1–2m at the DVR end
• Label each cable at the DVR with the camera position as you pull — not after

In the loft

• Cable ties or clips every 500mm on long horizontal runs
• Do not rest coax on top of insulation — it will be compressed over time and degrades the signal

External runs

• Use UV-stabilised (black) outer jacket cable for any external run
• Seal all wall penetrations with mastic to prevent water ingress
• Avoid routing where water can pool — water tracks along cable sheaths into wall voids
• Protect exposed external runs in conduit or trunking

Common Faults and Causes

Summary — Which Cable to Use

Related Documents

• IP Wiring — Cat5/6 & PoE
• HD over Coax with Baluns
• DVRs & NVRs — Understanding the Difference