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#39460 06/20/04 10:22 PM
Joined: Jun 2004
Posts: 2
radry Offline OP
Junior Member
I apologize for posting as I am not in the trade. However, this is not a "how-to" question, and since you guys are pro's, I dont know of a better place to inquire.

Dont ask me why I was doing it, but after toggling a switch, if I put my nose right up to it and sniff I can detect an slight odor which isnt there before toggling the switch or a few moments after.

I assume it is ozone, that I can compare to say an electric blender or perhaps a corded drill. The smell is not all that strong, and disapears after a moment or too. You wouldnt notice it if you toggled the switch and smelled the air as normal, you need to literally sniff the switch.

The cover plate or switch does not seem warm to the touch at all. I took the plate off and did not see any obvious signs overheating with my untrained eye. The switch in question is a Leviton 3 way, there is also a Leviton double switch in the same box (the size of a GFCI outlet) and when I toggle those switches, I do not detect this odor nor do I detect it when I try the same thing with other switches in the house.

So my question:

I know that all switches produce an arc, and an arc produces ozone, so is this what I am smelling? And is this a concern that I should have a qualified electrician look at?

#39461 06/20/04 11:14 PM
Joined: Jun 2003
Posts: 1,143
Both the electric blender and drill you mention contain "open" motors, with brushes, rotors, and commutators - these elements, even if properly cleaned, maintained, and aligned, will produce (for lack of a better term) "micro-arcs" due to surface irregularities from wear or manufacturing.

The odor is ozone, and a similar "micro-arc" is produced by the components inside the switch when it is energized. Possibly there is some remnant of the manufacturing process (dei lubricant) that is exaggerating the smell.

As long as there is no evidence of overheating (a smell when the switch remains in one position, or an odor grows stronger as time goes by; deformation of the switch body, discoloration of the wires to the switch or of the wire terminals themselves) I don't think there's a problem there.

{standard disclaimer] Since I can't be there to judge the situation myself, if you still have any doubt, call a locally licensed electrician to check it out. When it comes to peace of mind, price should not be an object.[/standard disclaimer]

#39462 06/21/04 08:37 AM
Joined: Dec 2003
Posts: 524
... Whenever I've encountered a "bad" switch,it's not the "smell" that's the symptom,it's usually a sound,like sizzling,and dimming/winking lights.This is usually because the connections to the terminal screws have become loose,or the "back-stabbed" connection has failed.Switch contacts can deteriorate as well,leaving the contact area pitted,and carbonized...thus all the ingredients for a poor connection.If you're concerned,have it checked,or replace the offending switch.

.."if it ain't fixed,don't break a Licensed Electrician"
#39463 06/21/04 03:42 PM
Joined: Apr 2004
Posts: 349
As Russ mentioned, making sure connections are tight is important if you have any reason to believe they are not. And if that is the case, any movement would tent to provide opportunity for arcing of wire connection areas.

However, it sounds like this is only noticable when operating the switch. Doug pointed out that a small arc is produced whenever current carrying contacts are made or broken. The size of the arc depends somewhat on the amount of current flowing in the circuit. So, a switch carrying more current will produce a somewhat larger arc, and therefore generate more ozone in the process. A switch with little to no current flowing will produce little to no arc (& ozone).

Hope this helps some. Have a close look at it to see if there is any evidence of loose connections and, if so, get that fixed.


There are 10 types of people. Those who know binary, and those who don't.
#39464 06/24/04 10:16 PM
Joined: Jun 2004
Posts: 2
radry Offline OP
Junior Member
Just to follow-up since the replies here are great. Thank you.

I had an electrician check out the box in question. He said that all connections at the switch and a wire nut connection in the box were tight. He said there was no signs of overheating. He said he could not detect an odor, however, I still do when I get my nose right up to the switch after toggling. So I suppose this is a normal thing as you guys describe. I think he may have thought I was a bit looney that I was sniffing light switches this closely.

He said an electrical odor is something one would have no question that something is dead wrong. He relayed a story about a customer and a lingering electrical odor caused by overheated outlet used for hair dryers and curlers etc. The odor remained even after the circuit in question was powered off for a few days.

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