Insteon 2474 2-wire and flickering with incandescents

[maxnorth]

I've got a 100-year old house with mostly 2 wires in the j boxes. Many of my 2474 2-wire switches perform fine, mainly where I don't have extensive dimming needs. But I've got two locations that don't work. When I dim these to around 60% or less, they will eventually turn off and then back on to that level, in sort of a slow, irregular flicker. My assumption is that the switch is failing to get enough power at these levels, or something.

 

It's not a huge deal, as my Lutron switches work fine in these locations and I can simply revert to that.

 

One location has 6 25-watt "candlestick" type incandescent bulbs in a chandelier. The other has 4 60-watt BR30 incandescents in cans. The locations have normal voltage levels.

 

I'm not getting any communication errors. The switches seem to steal enough power when the circuits are off.

 

Is this expected behavior with these 2-wires?

[bsobel]

How do you have these wired? Is this a three way circuit? The voltage at the switch should be the same regardless of the dim level so I'm wondering if you them wired correctly.

 

 

Sent from my iPad using Tapatalk HD

[maxnorth]

No, not a three way. Typical knob and tube wiring style: Line goes through the fixture and down to the switch, where the second wire is neutral.

[maxnorth]

Update to my own question. I had a chat with Insteon today and they report that this behavior can occur when one of the bulbs is close to failing. I will have to replace my bulbs and see if that fixes it. Also, in my testing, the Level 3 event viewer shows no device communication occurring during these intervals, so the issue is completely internal to the switch.