Can You Get Electric Shock From TV Aerial/ Sat Cable?
It’s common to have questions about how TV aerials function, including wondering whether or not they’re safe to interact with. This is a valid concern considering these products have a number of electronic parts, and most aerial owners are reluctant to call a professional every time they have a need for maintenance. In this article, I’ll discuss different aerial types and what safety concerns you need to have when interacting with them.
Electric Shocks and Aerials
If you want to splice the coax cable attached to your satellite receiver or TV, you might be concerned about the potential for electric shock. This is a valid concern, and I want to make sure that you know that there is no substitute for precaution when dealing with any electronic device.
To that point, it’s always a good idea to shut off the electricity first, just to be sure that any wires in the device are not live. If you’re not comfortable, you need to consult an electrician or an installer that has experience with aerials in Chester, before doing anything. Even if you do read and follow the information below, I can’t accept any responsibility for any injuries that might occur.
Do Television or Radio Aerial Cables Carry Electric Current?
The proper function of these devices requires that they carry an electrical current. They capture radio-waves from the air and transfer them to a coax cable that feeds into your television, radio, etc. That signal they pick up is alternating current electricity. This current is a much higher frequency than those that you’ll find in your outlets, meaning that the voltage is very low by comparison. Indeed, even the strongest signal in a television is only equal to about 1 / 100th of a volt.
Masthead Amps / Line Power / Sky Remote Eyes
There are a variety of television aerial systems that have a DC line delivering power through the coax cable along with the signal. This is the power line to the equipment that supports the device. Examples include masthead amplifiers, Sky Boxes, and remote magic eyes that provide you with remote control of your equipment. These range in voltage, but usually are around 5-12V DC for mastheads and 9-12V DC for remote eye systems.
Is There Current in Satellite Dish Coax Cables?
For the most part, satellite systems work in much the same way as television aerials. Instead of picking up signals from the air, however, they pick up signals that are coming from space – hence the name. The main difference, however, is that the signals coming from space are of such a low frequency that they need to be amplified before being sent to your receiver. This is usually accomplished by way of a Satellite LNB.
To accomplish this process, a continuous DC current is supplied to the receiver in order to power the LNB. This current is usually either 13V DC or 18V DC. While this is much higher than the voltage present in television and radio cables, it is still low enough to avoid doing any harm to humans, though it can certainly be felt.
In fact, it’s common to feel current when connecting cables on a satellite dish as you would typically be standing on a metal ladder or scaffold pole. In the presence of moisture in the air, this current can be much more noticeable, and even surprise you enough to cause you to lose your grip. While the current won’t harm you, the fall might! This is why you should always wear a ladder harness when operating on this type of equipment, and be sure to disconnect the receiver before beginning any maintenance.
Communal Television Systems
Communal TV systems differ from conventional television systems because they supply signals to multiple flats and equipment (potentially hundreds). Because of all the amplifiers involved, voltage can build up in the cables. That said, it is still highly unlikely that this accumulation of voltage would ever be enough to harm anyone.
This should not, however, be taken as a given. Communal TV systems are safest when connected to the earth, but some older systems might not do this. Worse, when working on these types of systems, it’s not uncommon for residents to try re-tuning their systems while they’re being worked on, resulting in the deleting all of their stored services. If you’re the one doing the work, you can expect who they’ll blame.
The CAI (the association for audiovisual professionals) rates homes safe up to having 5 different pieces of equipment connected to the TV system. Once the system hits 6 or more, it should be earthed, and the customer may have to sign a waiver declaring the installer not liability for any issues.
With 6 or more pieces attached to the system, it’s possible for a touch current to build up. This current is not necessarily dangerous, but – as with the satellite systems – the surprise from the small shock might cause one to fall and hurt themselves. Keep in mind that this is a legal precaution on behalf of the company, not an actual regulation.
Safety of Electrical Shock
Studies estimate that a human being can absorb up to 50V of electricity without risk of injury. This is why many systems operate up to 50V. Electronics like telephone lines and transformers all operate at or under this voltage. That said, as I’ve mentioned, the current itself is not always what causes injury, so it’s important to still be careful.
Poor Installation and Fault Condition Warning
In the case of older televisions and fault conditions, it’s possible that high voltage currents can be present in the coax cable. While not common, it does happen. In fact, old tube television had currents upwards of 25,000V traveling through the at times. Luckily, most new LED and LCD television do not come even close to this. The same goes for new cable systems that incorporate MCBs or RCDs, which will automatically cut the power supply if the current reaches an unsafe level.
Safety Measures to Consider
It’s good to keep in mind that most of the potential situations outlined here are “worst-case scenarios.” Of course, to keep these scenarios – however rare – from becoming a reality, there are a few safety measures you can consider.
· Always turn off all television equipment when working on cables
· Always turn off the electrical supply
· Use insulated cutters and tools (many are rated to 1000V)
· Always earth your television systems (even temporarily) to ensure safety
· When in doubt, call a professional
Questions and Comments
Remember, while it is usually safe to work on a television coax cable, it’s best to take proper precautions. Also, while I am happy to convey this information, I cannot bear any responsibility should it result in injury.
If you have any questions or comments, feel free to send them my way!