The Fundamentals of Checking NuTone Intercom Wiring for Problems 

Hi NWeber: I am somewhat unclear on what Model you have - An NM100 is a 3-wire System, which does not have plug-in connectors. I suspect that you have a NM200, which is a 6-wire System (8-wires if CAT5 was used) Using a "low-voltage pen" is pointless troubleshooting if you're trying to solve the problems. It is likely that you have wiring problems, since the odds that 3 out of 11 Remote Stations failed is unlikely (unless all 3 are Patio Stations) It would simple enough to use a known working Remote Station as a "test" Station and try it in each non-working loctation. You really need to check the cables for each of the non-working Station to determine what's wrong with the cables (breaks or shorts - probably breaks) With the specific information you gain from testing the cables, you may be able to use the remaining "good wires" to have some limited functionally on those 3 Remote Stations - Chris

Hi Chris. You are the best to reply so quickly. Yes, it seems it is an NM200. One of the failed stations is a patio. I fixed one by trying a good unit, and when I used the original unit elsewhere, it also worked. So inexplicably it must have been how the unit was connected to the wires, even though they looked good. The third unit has the solid vs stranded wires. Your video explained that those are problematic, so I'm guessing it is the wiring. I will use your video on checking the wiring and I may get back to you to find out how I can do a workaround to get limited usability. All I really want is intercom, not music. Thank you again.

Hi Kellyq21: Is this a NuTone brand system? Is the Entry Door Station a little Brown Plastic Box with a single Round Push Button and a Clear Plastic Name Plate to the left of the button? Please let me know - Chris

Yes, exactly. It is an old NuTone IK15WH as shown here: goo.gl/QmNuY2. Thanks and Happy New Year.

Good: The transformer can be mounted anywhere in your home - basement, garage, laundry room, coat closet etc. There should be 16 volts +/- of AC power on the second set of wires coming into the inside station - there is no electricity on the wires to the entry door station. What is the problem with your system? Chris

It's dead. It's in a commercial building and I don't know where the transformer is. So before I start taking down ceiling tiles or searching closets and walls for it, I am wondering if the problem is there is no voltage where there should be continuous voltage that I can measure anytime without worrying about whether triggers or switches are closed at the time of measurement.

There should be continuous voltage to the inside station. You can disconnect the 2 wires (that seem to come from the transformer) from the inside station and the measure for voltage - this eliminates the rest of the equipment from the testing, and only leaves the following as possible problem points: 1. Electrical Power to the Transformer (120 volts) 2. The Transformer (should output 16 volts AC +/-) 3. The Wire between the transformer and the inside station Often times in a commercial setting, if locating the transformer is not practical - installing a replacement transformer is simpler - Chris

Hi Tom: If you have clearly found that a cable run has a broken wire(s) and you believe it's inside a wall or other inaccessible location - there is no way to narrow down exactly where the break is - the best you can do is know that the break is "somewhere between here and there". In these cases it is often best to resign yourself to the idea that the most productive choice is to run a new cable. In some cases, following the path of the original cable works well, sometimes planning a new route may be easier. There is no standardized way to deal with these types of problems - It is entirely "Make-it-up-as-you-go" work - Chris

Hi ThePoseidon211: The best place to start is - Contacting me directly about about to proceed - Chris 925-743-8236