Existing 20a breaker. New 12/2 Romex. All receptacles, switches, hardware, lamps are new. Entire circuit pictured in diagram. Outlets are all pigtailed with no load. [Ground present, not pictured] Everything works, but....

Here's the problem... The switch on the switched outlet pops. (The first switch works fine.) The pop sound happens only intermittently, and only when the new fluorescent lamp is plugged into it (the intended use). This occurs with no other draw on the circuit whatsoever. The Fluo has the proper bulb wattage, & draws just .76a @ 120v. It also functions properly on other circuits. Using the switch/outlet without a fixture, or with a standard lamp, does not produce a pop in the switch.

At first I thought it was just a faulty switch, so I upgraded that to a new 15/20a. Same business.

I was able to trip the terminating GFCI just once, by flipping the switch multiple times in rapid succession, with the lamp plugged. Breaker never tripped.

This doesn't seem logical, but...
Should I upgrade everything on the circuit to 20a receptacles/switches?
Could it possibly be the existing breaker?
Do I need to move it to 15a breaker? or get a higher voltage lamp fixture?
I've eliminated everything but my wiring, and I can't find the cause for the fault/pop.
I'm left wondering what my rookie mistake is now... :-)

Thanks for any advice offered!

 

Do you mean it makes a popping noise?

 

Yup. There is a pop sound, as if it were a short, though the circuit functions properly. It's only audible when transitioning the switch on/off.

 

As an update on making myself crazy... I thoroughly reinspected the wire insulation within the switch housing. No problems at all. In testing, I was able to once again trip the terminating GFCI by rapidly switching the outlet on/off with the Fluorescent Lamp plugged in. The pop sound was still present in the switch housing, when turning it off. I was UNABLE to trip the GFCI with a 40w incandescent lamp in same outlet & no pop sound was present.

My next step is to replace the receptacle, upgrading to a 20a (probably GFCI).

Is there some better way to wire this fixture that might avoid the problem at the switch? (I know I could have used 12/3, but it's application didn't seem necessary here. I can't guess how it would alleviate the problem anyway.)

 

Not related to you problem but I see multiple GFCIs. Best practice is only the first receptacle and the rest fed from the load side of the first. The Pros are probably taking the day off so you'll have to wait for them to help you.

 

I suspect you're right about multi-GFCIs. It is overkill. I've had conflicting advice [concerning inspection] about using the load on GFCIs. The recommendations were to pigtail, so I did. Life would have been much easier if I had just used the load. I was too hasty to install them in the basement utility area, since I'm hoping to run the washer/dryer off the terminating GFCI.

...but, one problem at a time.

 

Is this popping coming from the switch? It could be a bad switch popping when it transfer the load, I am not sure about that GFCI pigtail senario ,either use the load side or install 1 GFCI breaker for the whole circuit.
Geo

 

Just curious, where did you hear that?

 

Geochurchi: I thought the same. Upgraded the switch to another new 15/20a. Same arcing pop sound when switching, with new Fluo Lamp plugged in. I cannot reproduce the pop sound with 40w incandescent plugged in. I'm assuming it's just the lamp now, but I cannot figure why, unless the ballast is defective in some way I don't understand.

CasualJoe: At this point I don't recall the references, but I saw it enough on other forums that it seemed worth doing. The consensus seemed to be: "Some county inspectors require this, so better to just do it." Personally, I thought it was odd, but it is less irritating of a fix to undo, rather than to install in a cramped box later.

 

All receptacles/switches upgraded to 20a. Swapped the original lamp to another new fluorescent fixture. Everything works like a charm. I suspect it was really just the fixture all along. The mystery remains why the original lamp was drawing so heavy to "pop" the switch, yet it still functioned perfectly. The only difference between the fixtures is that the new one [Utilitech] explicitly states "electronic ballast", while the first one [Lithonia] says nothing about it.

From here, I have a feeling that the explanation will require an electrical engineering degree.

Occam's Razor wins again.

 

Was the lamp a T12 or a T8? I suspect the lamp had nothing to do with your problem since it now works, but the ballast did. If it was a T8 lamp, both fixtures should have had electronic ballasts.

 

Both are T12. It appears that the original fixture was faulty (or at least ineffective for my needs). Ultimately, I tested it on another new 20a switched outlet (different circuit), and I got the same pop sound in that switch. --I think I mistakenly interchanged the term "lamp" with "ballast" here.

Doing repairs/updates to sell the house, led me to buy cheaper fixtures. In the next house, I'll be going with LED, or at least not "bargain-box" stuff.

 

Don't know if you were aware or not, but the T12 lamps those fixtures use haven't been manufactured since July 2012; 2 years ago. Whoever buys your house will be changing fixtures again in the not-too-distant future.

 

Ha! Actually, I was not aware of that. Thanks for the info. Good thing I installed it on a switched outlet, instead of hardwiring!