Saw something funny at work today.

[bad_idea]

One of the welders mounted (2) 4' fluorescent lights above his welding table because he's getting old. Very nice setup, mounted on a swing arm to facilitate loading the table with a forklift. He started tig welding some aluminum and the lights looked like a strobe light. One of our electricians fussed with it for a bit, but I don't know if he ever figured out the problem.

So what is the issue and how do you fix it? I am fairly certain it has something to do with the high freq from the aluminum tig welding.

 

[ForceFed70]

Strong EMI (like a TIG welder would produce) can light florescent tubes on their own.

I had a lab in college where we did just that. We used a high-gain directional antenae and pointed it down the length of some T12 tubes. Was neat to see the interferance patterns that were generated when we changed the frequency.

Or it could have been a voltage/grounding issue.

 

[bad_idea]

So how do I fix it?

 

[Tech Guy]

Are the lights on the same circuit or breaker as the welder ?

 

[SixStringMadness]

So how do I fix it?

Depending on the strength of the EMI, you might try to install metal screens of some sort in front of the lights that are very well grounded.

The trick will be using a screen material that is open enough to not restrict the lighting ability, but tight enough to catch the EMI, and defuse it to ground while still allowing light to pass through with adequate luminous effect to meet the need they were originally installed for.

This will be a trial and error thing. Do the screens attach to the lighting fixture, grounding it, or do you run a separate ground, and insulate from the fixture.... so on and so forth...

 

[ForceFed70]

So how do I fix it?

If it's flashing like that when the lights are turned on, you have problems with the ballast picking up EMI noise. Shielding the ballast and/or moving it further away may help.

 

[Zeke]

Just use another type of lamp. I might like a small halogen above my table, but I get by for the time being. If there are shadows, use 2 or more.

 

[pop pop]

"because he's getting old." NO. Because he is getting more intelligent!

Grey hair rules!

 

[bad_idea]

Is intelligent old people slang for 'his vision is degrading due to years of welding'?

 

[71flh]

I would guess that the 60Hz in the AC feeding the lamps is working in a harmonic of the TIG machine and creating a strobe effect.

Maybe an incandescent lamp in the area will reduce the problem?

"Grey hair rules!" Ha! Then I'm king!

 

[kbs2244]

"Maybe an incandescent lamp in the area will reduce the problem?"

That is what I would try.

I have seen the strobe effect on table saws, so it isn't just a welder thing.

I like the double halogen idea.

 

[gatchel]

http://en.wikipedia.org/wiki/Faraday_cage

 

[bad_idea]

i wish i could say how the electrician fixed it, but he did.

 

[I void warranties]

would grounding the table help? i understand the emi but leading that interference to least path of resistance may help too.