About 300 for 1/4", about 400 for 5/16", about 500 for 3/8".

crahner
As Blaster has mentioned 1/4" @ 300 Amps
1/4" is a big scalpel, Back in 1969 I used 3/8" to remove massive amounts of material making bottom dies out of 6"plate, they were for forming coal car doors that are under the rail car. I tend to use 5/32" now to remove a weld or even 1/8" to back gouge a CJP Weld.
Here is a chart from Red-D-Arc

http://www.red-d-arc.com/pdf/Air%20Carbon%20Arc%20Gouging%20Data.pdf

Good Luck
Marshall

Thank you very much Marshall,

I use 3/16" Regularly at around 225 amps or so, and have ran 3/8" Flat Carbons in the past off an Invertec V-350 Pro wide open at 425 amps with good success - Just never had a chart to go by.... Nice to have documented air requirements as well, that will come in handy the next time I get into a discussion with another "More is Better" fellow...

I always "loved" gouging with 5/8" rods at 800 amps  (with the good ol' reliable SA 800.)  You would start the machine up and step back 10 feet, because when they start up, they would sound like they are going to implode our planet!  As I recall, the gouging rod would barely fit into the holder.  Good times...to bad the vessel shop is deader than dead!

I've never actually thought about gouging amperages.  With the current outfit I'm working for, we use at most 3/8" gouging rods.  In the shop, 350 does the job, but in the field (because I love making the cables jump!) They work like a hot damn at 550 or so (welders in the sawmill off a landline)

I used to hate gouging, but the more you do it, the easier it gets.  The biggest lesson for me to learn was in which direction to keep the air facing (which would be behind the direction in which you're gouging!)

If you're gouging crap off of good material, find the line, gouge into the crap and the gouger will become your b*tch!

Besides, the better you get with a gouger, the less you'll need to run a grinder!