On 2008-01-02, Harold and Susan Vordos wrote:

"William Wixon" wrote in message
...

[ ... ]

that's funny (was thinking about this last night). that's something i've
always wondered about welded seam pipe. how come the electricity doesn't
flow around the back instead of through the joint. i mean, obviously it
works, but it would seem to me the juice would flow through the metal
instead of through the weld.

You'd think that, but you'd be wrong.

I have an old DoAll saw equipped with a blade welder. If you try to weld
pieces that do not complete a loop, it won't weld them. Sort of defies
everything you think you know about electricity, doesn't it?

I think that in *that* situation -- the welder is depending on the
current through the back loop to trigger the solenoid which brings the
ends of the blade into firm contact to make the weld. I've never
bothered to actually trace out the circuitry for the stand-alone blade
welder which I have, however.

Enjoy,
DoN.

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