Articles and whitepapers

Trade talk: Connectors for Custom Installation - a practical approach (2/9/2009)

By Dave Chester, Custom Controls

The delivery of a successful custom installation can, to a large extent, depend on the connections at the end of your cables. Bad connections can cost huge amounts of time, and can seriously affect the reliability of the finished system.

Cables with connectors already fitted may be convenient for applications such as patching, but for long runs they can be awkward to pull, and can be easily damaged during installation. As a custom installation company, it is rare for us to buy cables off the shelf. It is much easier to pull the exact length of cable required to a room than to try and make a premade cable fit. Indeed any installer worth their salt should be able to make cables to the right length, and should have the correct tools for the job. Termination tools, cable strippers, and the right variety of cables and connectors are all essentials in the engineer's toolbox.

To solder or compress?

Soldering is the traditional way of ensuring a good, solid connection, but while many installers solder on site, there are issues of heat and smoke generation which, particularly in commercial environments, can be problematic - one way to get a bad reputation is to set the fire alarm off in an office where a 1000+ staff are working!

Coax

We favour compression connectors for most types of application that use coax cable, as they tend to be quick and easy to install whilst providing reliability and a very solid connection. Compression connectors work by using a compression tool with a shaping die that compresses a connector with equal force around the entire neck of the connector. Internal sealing rings ensure a nice, tight connection.

Example of a compression connector. The ICM radial connector allows a connector to be compressed with the equal force around the entire neck of the connector. This increases its pullout strength, reduces ingress or egress, prevents moisture migration and maintains the integrity of the dielectric, jacket and centre conductor.

To prepare the cable, a good cable stripper ensures that the compression connector fits snugly and helps remove the guesswork or practice required for a good termination.

Example of a cable stripper, the Kramer coax cable stripper works for 26/28 gauge mini coaxes, as well as RG-6 and RG-59.

Cat5e

For Cat5e, we use the EZ-RJ45 terminator which allows you to pull the inner wires through the connector, to check for the correct order, before crimping your final connection.

Example of a crimp tool, the EZ-RJ45, available through Asheridge, is part of the EZ terminate system that has been designed to speed up the termination of Cat5 and Cat6 cables. EZ RJ45 connectors pass the conductors through the body of the connector and the EZ tool will quickly crimp and cut the wires of the in one simple operation.

HDMI

HDMI continues to be a challenge for our industry, and among the issues is how to install the cable. Although buying readymade cables flies in the face of a custom installation, there aren't many people who would attempt to make a custom HDMI cable up on site. For those who find that they absolutely need to do so, products are emerging that allow an HDMI connector to be terminated in the field. This will never be as simple as using a compression connector, but it does mean that an HDMI cable can be pulled through a tight portal, and the cable can be made to exactly the right length.

The AudioQuest field-terminated HDMI connector incorporates bayonet connections to manage the 19 conductors in an HDMI cable.

We tend to use readymade HDMI cables for single-room solutions, but for multiroom audio/video systems, we rely on fibre or Cat5e/6. There are faceplates that accept the fibre or copper connection and provide a neat HDMI socket ready for a short connection to the display. Some products, such as the Crestron DigitalMedia solution, even allow display control options and networking from the same faceplate.

The Crestron DM-RMC-100 wall plate range is designed to be installed discreetly behind a flat panel display. It connects to a Crestron DigitalMedia switcher or transmitter via a proprietary Cat5 cable or fibre, and provides a single HDMI output along with a variety of control ports.

Fibre optics

Most installers are familiar with terminating cables such as Cat5e and coax, but we are seeing an increasing requirement for fibre optic in domestic properties. Installing and terminating fibre optic can be challenging. The easiest thing to do is to purchase readymade cables of a specific length, but then any excess must be housed at one end or the other, risking damage to the fibre core and potentially compromising the final look of the installation if coiled cable is visible.

We prefer to provide a cable of exactly the right length, so our technique is to pull the fibre optic sheath around the home, which can then be trimmed to length. This doesn't contain the glass fibre, so it can be installed easily, without any specialist skills. We then have trained specialists who 'blow' the fibre optic cable through the sheath to the far end and terminate it. This technique can also be useful if the relatively brittle fibre becomes damaged post-installation, because the fibre can be blown out again and replaced.

Finding the right source

Regardless of whether we use fibre or copper cable, we nearly always source the connectors from the same manufacturer as the cable, since minute variances in specification can make a huge difference to the quality of the connection. Saving a few pence on a connector pales into insignificance when compared to the cost of an average project, but can make a big difference to the end result.

Conclusion

Planning can make the difference between a successful installation and a nightmare on site. Ensuring that you have the right numbers of connectors, plus an extra to allow for inevitable wastage, and the correct tools, can make installs relatively stress-free. Running out of connectors or trying to perfect the amount of sheath to trim from a coax can be frustrating, but the latter can be made easy with the right tool.

With fast-moving developments in our industry, particularly with the high bandwidth required for HDMI distribution, keeping up with the connectors and installation techniques is imperative. Whilst fibre may seem a bridge too far for some, it is the future, and I would advise either subcontracting to a trained installer, or getting the skills required in-house, now.

Dave Chester is the Managing Director of Custom Controls, bespoke home cinema installers and multiroom AV specialists.

www.CustomControls.co.uk