Electrical flash behind light switch plate

I am wondering if this is normal. I can see flashes of light sometimes when I flick on various light switches around the house. It's intermitent but most noticeable at night when there is little light in the room. I am nervous this is going to start a fire. Spoke with the developer they said it's normal. Any thoughts?

Reply to
affiliateian
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This has to be a troll. Even the worst arc wouldn't be visible with a switchplate in place.

But just in case it isn't; no, a significant arc when using a switch isn't normal. It will eventually cause damage or fire.

Reply to
Toller

It is normal and as long as the arcing stays within the housing of the switch it is also safe. Better switches than the cheapest "contractor grade" have a better chance of not arcing but it still can happen because thats what electricity does when a circuit is closed when a load is connected. I bet it dosen't happen on switches that go to receptacles where nothing is plugged in right now.

Now if it were a loud pop and the light flickered, then I would say go ahead and replace the effected switches because the contacts have eroded due to too much arcing.

Reply to
PipeDown

I put in the cheapos from the depot and can see a spark when I flick on a light in the dark, you have to be at the right angle to see it. Yes I have cover plates on.

Reply to
RayV

It is normal. All standard wall switches under load will cause an arc when making and breaking. In most cases it's small and not noticeable. If its hissing , crackling,or sparks coming out of the switch body, then change the switch

Reply to
RBM

flash spark normal....

cheap white or biege switch, with cheap cover plate.

just forget about it

Reply to
hallerb

If you say so. My house has "contractors" switches, and I have never seen an arc.

Reply to
Toller

I think God is talking to you. Pay close attention to the lights and you will understand what he is saying.

No, it's visible through the lever part of ivory colored switches, especially if it is dark in the room and the switch turns on something that is not a light or something in the other room. Would God do this if no one could see it?

These are little arcs. I think they're normal.

Reply to
mm

Question: How old is your house?

If it was built in the 70's you might be dealing with aluminum wire. You could also be dealing with aluminum wire and a light switch rated for copper, instead of switch with a CO/ALR or the older Al/Cu rating. Aluminum wire is notorious for loosening because of the warm-cool cycles with use. If the connections loosen sufficiently they will arc, and in some cases (like in our bedroom) quite spectacularly.

Steve

Reply to
Steve in Virginia

According to Steve in Virginia :

Aluminum isn't going to make any difference with switch contact arcing.

Minor, sometimes visible (especially when dark at particular angles) arcing is normal.

_All_ mechanical switches arc. The real question is "how much?"

Seeing it "through" some of the plastic isn't altogether abnormal either - depends on the plastic.

If you can hear more than a slight snap, or makes prolonged noises/sizzles etc, produces any visible smoke or smells of ozone, replace it.

Reply to
Chris Lewis

Evem "arcless" mechanical switches arc. But the whole mechanism is submerged in oil, so flammable gasses can't get into the switch and ignite, and then ignite what is outside the switch.

Reply to
mm

I believe you this is happening behind a switch in my basement I can see it when the lights are off at night looking down the stairs it flickers over and over. It is a bit worrying but I’m assuming it’s been that way and I just happened to notice now.

Reply to
t

Original post at Homemoaners is 15 years old.

New poster, are you sure this is not a switch with a built-in neon "night light". Neons of this type tend to flicker when on.

If not, then you need to have it investigated by an electrician.

Reply to
Anonymous

In the old days, switches were mechanical and made a very noticeable click. But by the 50's there were also silent switches, which I think used a capsule of mercury to turn on and off (Since thermostats used mercury, I assume light switches did too.)

But in the last 40+ years, all the new switches are quiet, they have little or no detent when going from on to off or vice versa, and I think mercury is seriously discouraged. So what is the method of switching inside? Have they gone back to mechanical but eliminated/without the spring and the detent?

I used to take them apart but only when they were broken, and I've been here 38 years and nothing has broken.

Reply to
micky

It is a sliding contact instead of a "snap switch" although that is still the trade name. I will break one if you want to see inside.

Reply to
gfretwell

Neon will be an orange-red flicker. Electrical arcs tend to be blue-white

Reply to
Clare Snyder

No mercury in silent switches - they just went to a softer detent and a different type of contact. The old snap switches were rated almost the same for DC as AC. The new silent ones have a VERY LOW DC rating because they open and close much more slowly

Reply to
Clare Snyder

It seems likely to me that you get more arc when whatever your load is has a significant reactive power factor.

When most loads were an incandescent bulb you probably didn't see much. With LEDs, CFLs, computers, etc. there is likely more.

Reply to
TimR

I vaguely remember long ago some early silent switches had mercury. Ancient history.

Snap switches use an "over center" mechanism with a spring to force the fast action. "Microswitches" also use an over center mechanism. There are some high amp (1000+?) disconnects that use an over center mechanism.

Silent switches use the AC zero crossings to break the arc.

In high school the 50A dimmers on the stage had tiny toggle switches and switching was very quiet. The contactors had a tube with mercury. When switched on a solenoid pulled a floating iron cylinder down into the mercury, which rose to contacts.

Reply to
bud--

There MAY havebeen a few "early" silent switches - but very few - and they wouls not work if installed any way otherthan straight right-side-up vertical. Also, silent switches do NOT use "zero crossing" as they have no electronics in them. They use a simple "spring lever contact"- like a set of ignition points with a lightly spring loaded detent.

The "snap" switches DID use an over-center "knife" switch that "jumped" open or closed in a millisecond or two.

Reply to
Clare Snyder

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