Arc Flash & Distance Question

[leeave96]

At my day job, the welding guys do a really good job of keeping their arcs behind curtins, but every once and a while, from a distance you can see an arc flash and your eyes try to look in that direction - which of course I don't.

My question is - is there some kind of formula that causes the damage from looking at an arc to dimish over some distance. For example, if I weld something in my back yard and the old lady next door - some distance away, decides to watch (she watches everything!), are her eyes going to be damaged? When welding out in the back yard, how do you keep from causing eye damage to the neighbors?

Thanks!

[tigman250]

as far as i know welding arc dosen't get any dimmer with distance, in our 100' shop someone can strike an arc on the opposite end and it's still very bright. i don't know of any magic distance where it won't harm your eyesight and unless your neighbors are a mile away they are within range. if you are worried about it you can get the welding flash hiders at any LWS and build a cheap frame to stay in good with the neighbors.......or if they want to watch that bad pick them up a hood! lol

[Coalsmoke]

A minimum of 30 meters at 100amps (about 100').

[fun4now]

i dont know the formula, but it would have to lessen in afect with distance. kind of like getting a sun burn in arizona V/S New york. you will still get the sun burn in New York it just takes longer. humm unless you are from arizona in New York in witch case you will likely tan. but i degress, the light is going to diminish intensity with distance lessening it's ability to burn the eys. your naibor is not likely to get a burn from a quick flash but will no dought go to bed seeing spots if she watches you weld all day.probly best to warn her against it.

[Coalsmoke]

Once again:

A minimum of 30 meters at 100amps (about 100').

[ShieldArc]

In an old 1945 welding book i have say's 35 feet. That seems too close to me though to be looking at stick welding.

[BillC]

Bill,

Radiation from a point source is subject to the inverse square law. At twice the distance you get 1/4 the radiation per unit area. At three times the distance you get 1/9 of the radiation per unit area. etc. etc.

Regards,

[lowlypawn]

Bill,

Radiation from a point source is subject to the inverse square law. At twice the distance you get 1/4 the radiation per unit area. At three times the distance you get 1/9 of the radiation per unit area. etc. etc.

Regards,

Thank you for someone else knowing this. If it were not for the above law the night sky would be solid white with stars, It clearly is not.

[Coalsmoke]

Thank you for someone else knowing this. If it were not for the above law the night sky would be solid white with stars, It clearly is not.

yup, that's a great way of explaining it, I'll keep that one in my grab bag for future use