On Nov 27, 4:21 am, Ignoramus17419 ignoramus17...@NOSPAM.
17419.invalid wrote:
I would begin with the assumption that the arc starter is
defective. It should not trip GFCI. Try measuring current on the
ground line when it is not plugged into GFCI.

Hi Ignoramus. I found out a solution, but perhaps not the cause of
the problem.

I was able to trip the GFI, even though the arc starter was plugged
into a non-GFI output. That seems to suggest that the unit was not
defective. Then, I unplugged all loads to the GFI outlet. No more
tripping! The loads included a microwave oven and a trouble light.
No matter. I don't use these while welding, but the trouble light can
help start out, since I do not have an auto-darkening helmet.

Then, I tried disconnecting the welding cables from the arc starter.
No nuisance trips, and the fluorescent lights stopped flickering when
the HF was turned on, but I could not weld.

The compromise was to plug everything in a non-GFI outlet, and unplug
everything from the GFI outlet. The lights would still flash, but
this was bearable, especially after the arc started.

TIG welding is a blast, especially after developing the skill to stick
weld 1/16" sheet metal. I have a feeling that that outdated skill
will soon atrophy . It will also work for filling blown through
holes easily, with no slag inclusions. Just fantastic!