Light switches arcing

[j2020]

Could I please get some suggestions on potential causes for arcing at these light switches? It is occurring in a couple of different areas of the building on both decora light switches and dimmer switches. The maintenance folks think it could possibly be housekeeping getting the switches wet when cleaning.

 

[growler]

The maintenance folks think it could possibly be housekeeping getting the switches wet when cleaning.

Getting them wet could case that. Most of the time when you find heating like that it's caused by a poor connection.
Moisture leads to corrosion and that leads to a hot connection.

Could just be old because those are old type screws on the devices.

 

[ptonsparky]

Could I please get some suggestions on potential causes for arcing at these light switches? It is occurring in a couple of different areas of the building on both decora light switches and dimmer switches. The maintenance folks think it could possibly be housekeeping getting the switches wet when cleaning.

What are they cleaning with? Diesel?

 

[dpcarls1598]

If they are 277v, the cleaner will certainly do that. I’ve replaced way more switches since COVID than in the previous 30+ years…. Our staff was spraying the switches directly then wiping the fronts down. Since encouraging them to spray the rag then wipe the switch, it has nearly stopped. Not sure what the cleaner was but even plain water and 277v bites back.

 

[drcampbell]

Diesel fuel is non-conductive.

 

[ptonsparky]

Diesel fuel is non-conductive.

Spray it, compress it, ignite it.

 

[acin]

Is the divider in the 2 gang for different voltages?

 

[Fred B]

Mind if I use those pictures for an inservice sarefty training I occasionally do for other trades? Great illustration of "Why not".

 

[hillbilly1]

If it’s 277, those switches do not look like they are rated for more than 120, judging from the body style. That would be another factor.

 

[Frank DuVal]

Spray it, compress it, ignite it.

When compressed, it ignites itself. Hence the name compression ignition.

Spray it, compress it, boom, repeat.

 

[synchro]

Spray it, compress it, ignite it.

When compressed, it ignites itself. Hence the name compression ignition.

Spray it, compress it, boom, repeat.

I would say compress it, spray it, utilize torque from burning and expansion during power stroke, drive exhaust out, pull in intake air, repeat (for the common 4-stroke engine).
Fuel injection occurs within several degrees of TDC (Top Dead Center) at the end of the compression stroke. And so the compressed air at that point is hot enough to ignite the sprayed fuel without significant delay.

I find it interesting that in gasoline engines a high octane rating is desired to have resistance to compression ignition, whereas in a diesel engine you obviously want it to be amenable to compression ignition. Diesel fuels instead have a cetane rating which indicates the rate at which the fuel will ignite within hot compressed air. And so you need a higher cetane rating for high speed diesels, but a lower one is appropriate for large, low RPM engines such as in some marine applications.