What is a Shielded Wire?

Mary McMahon
Mary McMahon

A shielded wire is a wire which has been covered with protective sheathing to reduce the amount of electromagnetic radiation which it emits. This is designed to reduce the amount of electromagnetic interference (EMI) associated with that wire. There are numerous types of shielded wire available which can be used in many different applications. Hardware and electronics stores usually carry this product, and can order specialty products by request from their customers if someone needs a particular type, brand, design, or style for a project.

People who are not sure about what kind of wiring to get can ask a contractor or electrician for advice.
People who are not sure about what kind of wiring to get can ask a contractor or electrician for advice.

Many people are at least passingly familiar with electromagnetic interference. Some examples include distortions on monitors and televisions caused by EMI, crosstalk on mobile phones and cordless telephones, interruptions in radio playback, and flickering of electric lights. Electromagnetic interference can be caused by nature, or by various devices in the vicinity, especially if wires cross close to each other. It can damage a circuit or interfere with its operation, and it is often extremely irritating.

With shielded wire, even when wires run near each other, they cannot interfere with each other. People can use shielded wire wherever wiring is likely to overlap, and shielded conduit for things like household wiring. People opt to use shielding if they suspect that a particular device might cause electromagnetic interference. For example, a big television could be fitted with a shielded wire as a power cord so that it will not cause problems with other devices in the area.

Companies which design shielded wiring and shielding kits generally test their products thoroughly to confirm that they will work. The wire may indicate the tolerances it has been tested for so that people know if it is appropriate for the setting or not. It is important to select a product which will provide adequate shielding or interference can continue to be a problem despite the use of shielding. People who are not sure about what kind of wiring to get can ask a contractor or electrician for advice.

Many different types of wiring are made available in shielded form for convenience. People can also add shielding to existing wiring with various wire shielding kits which are often available through electronics stores and the electrical department at places like home improvement stores. As a general rule, it tends to be more expensive to install shielded wiring, but the wiring may be necessary or strongly recommended to keep devices functioning properly, in which case people may view the expense as acceptable, given the conditions.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


@tanner182 - I'm always worried that my dog will get zapped. I know a lot of people who have pets have trouble with animals chewing the shielding off of the wires. All of the wires in my house are shielded, but I still try to hide them where my dog can't find them.

My cat has chewed through cords before, luckily they are usually the ones in the kitchen that are unplugged. I keep everything unplugged just for the reason. Animal teeth punch right through the shielding -- when is someone going to invent animal shielded copper wire?


amsden2000- Yikes.I used a lot of shielded electrical wire when I was younger -- my parents bought me robot building kits. The kits were the kind you had to build from scratch, so they taught me how to safely hold wires and so on.

I've never been zapped from a wire, but one of my buddies has been. He was messing around with a fancy radio kit and had cut it in the wrong spot, so it had a small bare spot.

When he grabbed the wire to plug it in, he got a good zap. He was fine just a little freaked out -- so we shielded the whole thing in electrical tape.


I remember when I was little, I was watching my dad work on the car. He was doing something with the battery -- I'm not sure what, I was really young -- and he managed to cross the wires.

Thank god that the wires were shielded! Dad's not always the most careful people around. It really freaked me out because it shot sparks all over the place.

Dad flinched back so much, I thought for a second that he got shocked. Luckily, it was the startled shocked not the electrical kind. I'm always really careful when dealing with wires -- shielded or not.


@robbie21 - No, you don't need shielded wire for your speakers. The standard advice is that you should never use shielded speaker wire as it can change the sound and it isn't necessary anyway. Don't ask me why, because that's where it gets too technical for me.

If you have a fairly small system, you can use a fairly thin wire. You can get it cheap at a hardware store by the foot, or sometimes you can find even cheaper rolls of it at a store like Walmart.


Maybe this is a dumb question, but how can you tell if wire is shielded or not? I I'm setting up my my new home theater system, but I'm not sure if all speaker wire is shielded or not. Help me out - what should I be looking for? Do I need shielded wires?

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