How Many Wires Are In Your Old NuTone or M&S Intercom System?

Written by
Home Controls
Published on
April 28, 2015 1:24:00 PM PDT April 28, 2015 1:24:00 PM PDTth, April 28, 2015 1:24:00 PM PDT

Is your NuTone or M&S home intercom system old and out of date? Is it time to upgrade your system with a contemporary and stylish new home intercom, complete with modern features and the latest technology? The great news is that you don’t need to completely replace everything; you can still use the wires from your existing system. This means you don’t have to run new wires which saves you the need to call an electrician. A great money and time saver!


The first thing you need to do, even before you purchase a new system, is to determine what wiring system your current home intercom system uses. Why? Older systems use different types of wires, and the replacement models – also known as retrofit intercoms – are configured just as differently to work with each wire type.


There are four distinct wiring configurations: three-wire and four-wire are the most common, plus there is six-wire and the rare eight-wire. These wires are self-explanatory. A three-wire system, for examples, uses three wires. These wires connect your main intercom – also known as a master station – to the intercoms in each of your rooms – also known as room stations.

Again, you don’t need an electrician. You can easily determine the wiring system yourself in just four simple steps.




Four Simple Steps


Grab your screwdriver and head to one of the room stations – thats an intercom in one of your rooms. For this process, you can ignore your master station. The master is big and bulky with a lot of wires, and a room station is much easier to handle.


1.) At your room station, find the screws that hold the intercom to the wall. Each intercom is different, but it should be as easy as removing the screws from a wall plate. Remember to turn the screwdriver to the left – lefty loosey, righty tighty.

2.) Carefully pull out the intercom unit from the wall. Be gentle; you don’t want to pull the unit too far out that the wires rip off the back.

3.) Turn the entire intercom unit around just far enough so you can see where the wires are connected. Count the strands of wires connected to the intercom. If there are three wires, then you have a three-wire system. If there are four wires, then you have a four-wire system. And so on. (Connections vary from model to model; however, most intercoms connect their wires with a screw terminal.)

4.) Turn the intercom unit back around and reattach it to the wall with the same screws.

That’s it. You are done. Once you know what wire configuration your home intercom system uses, you are prepared to find a compatible replacement intercom.


There are a several choices that work well as replacements for old intercom systems, including NuTone, M&S Systems and the Intrasonic Technologies (IST) brands. To learn more about these retrofit options, read our blog entitled How to Replace Your Old NuTone or M&S Intercom System – or just give our friendly customer service department a call at 858-693-8887.