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What type of cable should I run for my new projector, and are there any other wiring considerations that I need to make?
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Wiring to a projector, while very similar to wiring for a television, is also quite different because the wiring is more often buried behind walls and ceilings, which limits access. This means that while a basic answer to this question is often given, especially by builders and installers who just want to get in and out with whatever solution may work today, in the long run the wrong choice could cost you more money and time than is necessary.

Consider your installation. Where is your projector going? Is it going at the back of the room with source equipment directly below the projector? Is it going a few feet from the back wall with equipment on the other side of the room or hidden away in a closet? If you're doing a ceiling mount, do you have an attic space above where the projector will be located? What type of access do you have to either add or remove a cable that needs to be replaced or upgraded in the future? What type of access do you have now vs. later—will walls need to be cut into to run a new cable, or are you dealing with new construction with open access? If you do have access to replace a cable in the future, how difficult will it be to do so, and are there options to avail yourself of now to make that process easier later?

That’s quite the list of questions to ask, but those are the right ones to ask yourself before any cabling is run to the projector location. That’s because the current standard for video to a display has already been announced as obsolete. That’s right, the 4K standard is going to be upgraded. The current 4K standard for HDMI, called HDMI 2.0, is rated to carry up to 18 Gbps of information. That’s about twice the capacity of the previous generation of HDMI cables, and less than half of the 48 Gbps capacity that the next generation of HDMI 2.1 cables will be carrying. The key is the speed rating of the cables and that they are certified for that speed.

At CES earlier this month, the HDMI Forum finally announced its Ultra High Speed HDMI Cable Certification Program for full 48 Gbps, HDMI 2.1 cables. Those certified cables (as opposed to those which claim this capability but do not carry certification) should be available soon. But, if you decide to install a certified 18 Gbps HDMI cable today because it's either less expensive or all you need for now, it’s important to understand that while it may work just fine for a few years, it likely will need to be replaced at some point with a 48 Gbps HDMI cable—or something even more advanced—to get the best possible image quality with the newest generation of video sources and projectors on the market. Even with HDMI 2.1 coming into the market now, the continued evolution of the HDMI standard, as well as an increase in the data rates for future video and audio formats, are virtually guaranteed.

So, the key is to not just think about which cables you should run today, but also how you will replace the cables in the future if you need to and what steps you can take today to make that process easier. We will consider three potential situations. The first setup is if you have fairly easy access to add or remove cabling at the projector location now and in the future. The second situation is if you are doing new construction and have no drywall in place, making access simple now but more difficult later. And the last scenario is when you know you will not have access to replace cabling in the future after the cables are run without cutting holes in drywall. These last two situations may sound very similar, but one key aspect of dealing with new construction can make all the difference in the world.

While it may seem obvious, the term "future-proof" applies most easily to those who can just swap out their cabling anytime they want to. Those with a projector located near their equipment who just need to run cabling up a wall or into an attic space, and who will always have access to do so, will have the most future-proof options available to them.

If you're in that situation, all you need to do today while the technology is evolving to HDMI 2.1 is run an HDMI Certified Premium cable of sufficient length, which will be rated to 18 Gbps speed. These cables do not need to cost a lot of money, but the certification at the length used is very important. 4K HDR content that runs right up against the 18 Gbps rating is a top cause of complaints of owners of cables and simply causes a lot of problems when cables don’t work properly. So, getting certified cables does help, but still isn’t a guarantee, especially at longer distances. Nontheless, since the cable can be easily replaced in this scenario, if you just make sure to buy from a retailer with a good return policy and warranty, you'll be well covered. Just the single HDMI cable should be enough to get video to your projector, with no need for back-up cabling or other additional work.

The next scenario is new construction. A single word is often repeated by those who care about future-proofing installations, and that word is conduit! Flexible conduit is usually easy to install during new construction. It should provide at least 1.25-inch of inside diameter to allow for easy addition or removal of cabling. HDMI cables are larger than the more common 0.75-inch conduit can easily accommodate. Conduit should be flexible and in-wall rated—similar to what you may find as the hose for a vacuum cleaner, but designed specifically for in-wall use and cabling. Builders often refer to this as "Smurf Tube" as there are versions which are blue in color. The typical color for low-voltage in-wall use is actually orange and is readily available for purchase online in fifty-foot lengths. It may cost $100 or more to get that conduit, and some additional cost to have it installed during construction, but once it is in place (with a pull string inside of it!) new cables can be run inside the conduit at any time now or in the future. You can now run a Certified Premium HDMI cable, or more advanced Certified Ultra High Speed HDMI cable, inside the conduit during construction or after as it pleases you. If you choose to not run conduit when you have the chance, be aware that you end up in the last category discussed below, which is not where anyone really wants to be.

That final scenario is zero access, and is perhaps the most common situation that people run into. Builders are usually terrible at audiovisual installation and design and rarely provide conduit for new homes, even when that home has a specific theater space. This means that for any installation not originally planned for, or for situations where cables have to be updated, drywall will need to be cut open, new cabling will be run, then walls will need to be patched and painted. This can cost in excess of a thousand dollars to have others do, and paint and drywall patches may never quite match up with an existing paint job. Spending some more to add conduit at this time may be possible, but often isn’t, so getting the right cabling in place and trying to future proof as much as possible is the goal.

This means that you will want to "over-cable" the installation. Most commonly I have recommended running two Certified 18Gbps HDMI cables as well as two pieces of unterminated Cat6a cable. (As Certified 48 Gbps HDMI cables come into the market, these would obviously be a better choice.) The two HDMI cables will offer redundancy in case one cable fails unexpectedly. The cables, if at all possible, should be tested to ensure they carry their full rated bandwidth prior to installation.

The Cat6a cables are installed as back-up for future functionality. As 4K signals currently can be sent over inexpensive category cabling using technologies like extender kits and HDBaseT transmitters and receivers, it is likely that future formats will leverage category cabling to allow 8K and other 48Gbps or higher signals to be transmitted. Put them in now, and and hopefully the walls will not need to be opened again—that, of course, being the goal.

With these three different scenarios, the one constant is using Certified HDMI cables rated at least Premium (18 Gbps), but there are a few other cables which may need to be installed depending on your specific setup. First, power must be run to all projectors. This is not something that is typically installed by a low-voltage or audiovisual contractor, but by an electrician. Once installed in a location, it is there forever and shouldn’t cause any issues at all. Another option may arise when a projector offers internal smart streaming capabilities for things like Netflix. This smart functionality requires an Internet connection which is best served with a wired network connection to your home router using Cat cable. Of course, you can always provide smart functionality to your projector with a third-party streaming device from Roku, AppleTV, FireTV, Android, or others to provide video to the projector and audio to a surround system or speaker bar for your theater setup.

Yet another possibility is a required cable for a projector's 12-volt trigger connection if there's a plan to have it trigger a motorized screen directly from the projector, which is typically just a two-conductor cable. Finally, though it is rare to use any built-in audio within a projector in a permanent installation, some models do have connections at the projector that can provide audio out to a soundbar or surround sound system. If these audio connections are present on the projector and there's a chance they may be utilized, then the proper wiring, most often an optical audio cable, should be installed. It is worth noting that surround-sound gear or other audio equipment, and the rest of your equipment, also will need some wiring separate from your projector installation wiring. It is best to consider a projector as a video playback device only, and handle your audio by a completely different setup. So, when you wire for your projector, focus almost entirely on getting video to it, then examine your audio needs.

Make sure all cabling you put in place has enough length to reach to the projector once it emerges at the ceiling or wall location and enough length to reach equipment at the other end, including the ability to snake through planned equipment cabinets or up the sides of a rack. Do not use HDMI wall plates. The integrity of high speed 18 Gbps HDMI connections are often compromised by the additional connections and cables introduced by HDMI wall plates. Instead, use bullnose or brush-type low-voltage wall plates to pass all cables through on the way to their final destinations and still keep the installation looking nice.

Paul Vail has been a professional audiovisual engineer since 1999. He works day-to-day for a commercial integrator and runs his own residential installation company, AV Integrated, out of Chantilly, VA, covering the greater Washington D.C. area. He has been the moderator of the ProjectorCentral Big Screen Forums from their inception more than ten years ago and has installed hundreds of projectors over the years, from entry level basement setups to 4K simulation systems using the latest in 3-chip DLP technology. He enjoys helping others learn about how to get the most value for their money, and setting realistic expectations and goals for the setup they are working toward. You can submit your question for Paul and ProjectorCentral Q&A by clicking here.

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