Haunted Touch Lamp - or AFCI detector?

[ELA]

We had a strange one occur at our house this week. My son said that during the day he witnessed a bedroom touch lamp blink intermittently at the same time that an Ionized Air Cleaner (IAC) turned itself on ... Spooky huh?

The next night we awoke to the very same happening. The table lamp was flickering and the Ionized Air Cleaner (IAC) came on by itself at "turbo speed".

I found that whenever the IAC was turned on/off manually the touch lamp would blink on/off intermittently. Even when power was turned off, (but still plugged in), I could bang my hand on the side of the IAC and the lamp would flicker on/off.

I took the air cleaner into another room, away from the lamp, and the IAC appeared to work just fine. Lamp was unaffected.

So ... I am aware of the fact that touch lamps are very susceptible to transients and RF (and certain spooks). At this point I suspect something inside of the IAC is generating EMI , even though it seemed to work fine.

I took both the IAC and the lamp into the garage and I could duplicate the same scenario as in the first bedroom. I further found that the lamp would only be affected by the IAC (on/off cycles) when the lamp was physically within 5ft of the IAC (but electrically on another circuit), or was electrically connected within 12-15ft (on the same circuit) that the IAC was plugged in.

More investigations to follow. At this point I know what the cause is but would like to try some more experiments and I am little afraid right now, being so close to Halloween and all....

I find it very interesting that if it were not for the touch lights presence in the room I may not have suspected a problem with the IAC (other than that turning itself on thing)
The unit does have a timed mode where it can turn itself on automatically and so at first I thought that might have accidentally been enabled, but it was not.

What do you think, haunted or not?

I may have to go out and buy an AFCI to see what it thinks:roll:

 

[wptski]

The closest I can come to that is I once had a soft-touch/dimmer unit from Radio Shack that one would use with a ordinary lamp. Sometimes when a overhead bedroom light was turned ON the living room lamp on the soft-touch/dimmer would come ON.

Many years later the overhead light started to blink which ended up being the wall switch. I assume now that the problem was caused by transients.

I'd be interested in testing that switch now but that was years ago when I wasn't really interested in what was causing the problem.

 

[480sparky]

What makes you think an AFCI is going to solve the problem? The only thing it will do is open the circuit if it detects an arc fault.

You simply have two items that are not compatible. Move one or the other.

 

[ELA]

What makes you think an AFCI is going to solve the problem? The only thing it will do is open the circuit if it detects an arc fault.

I do not think I said that, did I?

You simply have two items that are not compatible. Move one or the other.

Wrong. They have worked together for years now with no problem.

 

[480sparky]

I do not think I said that, did I?

Then what do you expect to gain from installing an AFCI?

Wrong. They have worked together for years now with no problem.

Well, NOW you tell us.

 

[ELA]

My AFCI reference was to compare the blinking lamp to an Arc Fault indicator (of sorts).

I put an ohm meter on the hot and neutral of the IAC and it measures 50 ohms. When I bang on the side of the unit this value did not change.

I took the IAC apart and observed the printed circuit boards with the unit plugged in and when I bang on the side of the unit I can see and hear arcing coming from the underside of a pcb, directly underneath a relay.

I have yet to remove the circuit boards to confirm but I suspect a cold solder joint is at fault. I believe the relay coil is directly across the incoming line and that the loose connection to the coil is arcing. This produces both conducted and radiated noise that causes the lamp to flicker.

I expect that once I repair the solder joint all will be fine once again.

The interesting part is that there is very definite problem in the IAC cleaner that requires fixing. This even though on the surface it appears to run fine when not located near the lamp. (I suspect over time it would have degraded further and would be more obvious)

Without looking at it very closely one might assume that the two are simply incompatible.

It appears that when cold the joint arcs severely and once running it temporarily "mends" itself.

I am tempted to try connecting an AFCI breaker to it to see if it would detect the arc and trip. On one hand I would say no since the series arc is probably about 120/50 = 2.4 amps, which is less than the 5 amps required.

I am just a little curious if the AFCI might still trip (depending upon the model used and how well it is protected against "nuisance" tripping.)

 

[wptski]

I had a heat blanket and after just turning it ON to warm up, I heard a crackling sound from the connector. Two of three wires coming from the controll box must have had a cold solder joint and were arcing.

One had arced away so much I had a hard time soldering because of the large gap that I had to bridge.

 

[ELA]

As a kid I still remember helping my buddy carry his smoldering mattress out of the house. The mattress had been compressed up against a plug and an arc had developed that ignited the mattress.

We just happened to be in the house at the right time to notice.

AFCIs seem like a great idea but I do wonder if their ultimate goals are actually achievable ( at a reasonable cost).

I did not have time to work on the IAC today.

 

[Buck Parrish]

Will afci trip if polsrity is reversed ? I am talking in side the appliance.
I am not sure. But, I don't think useing an AFCI will help solve the problem.
It may be similar to a transient voltage issue.

 

[ELA]

Will afci trip if polsrity is reversed ? I am talking in side the appliance.
I am not sure. But, I don't think using an AFCI will help solve the problem.
It may be similar to a transient voltage issue.

I was never thinking of installing an AFCI to resolve this issue.
I was comparing the blinking touch lamp as an inexpensive Arc Fault detector

As stated I would be curious to see if an Arc fault breaker would trip on this but not to resolve anything. This is occuring in my own home so I have the luxury of spending my spare time to thoroughly investigate and to learn from it. I understand that in the "real world" electricians need to resolve issues as quickly as possible and move on to the next job.

 

[ELA]

Issue was Across the Line Capacitor intended to reduce EMI - not produce it!

Issue was Across the Line Capacitor intended to reduce EMI - not produce it!

Here is a picture of the PCB that contained the component that was arcing. It is the yellow part and it is a 0.68 uf capacitor connected directly across the AC line input. Normally the purpose of the capacitor would be to suppress EMI. I find it very interesting that in this case it had become an EMI generator.

Here is a picture of the underside of the PCB. You can see the connection that is missing a bit of solder directly underneath the yellow cap.
As poorly as this was soldered I am surprised the machine has run for 3 + years before demonstrating this behavior.

This explains why when I took an ohm meter reading that I did not see any change when banging on the side of the unit. The 50 ohm reading was the input impedance of the transformer (to the right of the cap).
There is a relay that energizes when the unit is first plugged in but it was not part of the cause of this issue.