The enemy from within: Noisy Switch Linc Dimmer.

[Michaelv]

I have a large home with 4 floors and 158 Insteon Devices plus 10 access point 15 filter lincs and an ISY99ir Pro. I suspect that I may have some noise on my power line. I am trying find the source of the noise with a battery powered AM radio tuned to dead air where I get this awfull buzz. I turn off breakers until the noise disappears. I then go through that circuit until I find the culprit. It was a switch linc dimmer that is part of a four way circuit that controlls about 10-65 watt recessed lights. The switch that carries the load is a 1000 watt dimmer so I am not overloading the circuit. do the other switches on the circuit need to be 1000 watt dimmers? I would not think so. When I turn these lights off, the hum goes away. I was under the impression that these switches were engineered not to put out power line noise. I would imagine I need to replace. Do you agree? Lastly,I have 3 pendant lights, that are 300 watts each on another 1000 watt dimmer that after they have been on a while they start to blink some what. Especially when there is insteon traffic. What is up with that?

[Brian H]

The noise on the AM radio is not that uncommon. Even manual dimmers can make AM noise. It is the noise from the triac in the dimmer modifying the AC waveform.

No the unloaded controlling ones do not have to be 1000 watt models. Some have even link Icons to Switchlincs as the second or more switch in a multi-switch setup.

 

How old are the Switchlink's that start to pulse? Older ones have been known to pulse with power line traffic.

[Michaelv]

The version of that switch is V.28. It was installed about 6 months ago.Is the noise the switch putting out going to interfere with Insteon Traffic? What I did not mention in my initial post is that I am trying to find the source of this noise as it is causing a problem with AM radio reception in a whole house audio system as well as rolling lines on the screens of some of the TVs in my home. I did not hear this type of noise from any other insteon dimmers in the vecinity. Should that switch be replaced?

[MikeB]

I would certainly swap it out to see if a replacement switch shows the same behavior.

[Brian H]

If the others don't seem to be as noisy and it is the one pulsing. I second Mike B's thought of try another one.

 

You may also want to double check the connections are tight on the switch and loads.

[ergodic]

Also, understand that the higher the load and the longer the circuit the more amplitude pulse noise will be radiated. This is just in the nature of switching power circuits. Generally the noise will be at max at about midpoint of dimming where the cutoff is the largest. As you dim to either end of the waveform the noise should decrease if this is the source.

 

A 10x65W lighting circuit is getting up there - I'm not surprised it buzzes your AM radio more than the others. Good argument to buy an Internet radio.

 

The herringbone bars on the TV suggest to me a voltage fluctuation on the line possibly as a result of the loading. This could indicate a wiring or load issue. You might want to put an RMS meter on that circuit to see what happens as you dim up and down.

 

You don't mention the type of recessed lights you have, but the 65W number suggests a low-voltage unit. If these are electronic LV cans then the issue is the fixtures themselves and you absolutely need to filter that load past the dimmer with a Filterlinc or something similar wired-in.