According to Jeff Wisnia :

The reason I suggested using a small bulb rather than a meter is this.

Just in case you DO have a dead short between the "hot" side of your 240
volt supply and the metal body of the lamp, then connecting that
grounded wire I suggested directly to the lamp body through an ammeter
would cause one heck of a lot more current than the 0.4 A you mention,
possibly enough to damage the meter before the fuse or breaker opened,
unless the meter was set to something like a 400 amp range. Capiche?

The meter would probably _still_ explode.

I saw the result of someone mistaking a 100A DC ammeter for an AC
voltmeter, and sticking the probes in a 120V socket. Not pretty.
Yup, the breaker tripped. But the meter innards had vaporized,
and the industrial grade receptacle was destroyed.

Shouldn't put an ammeter across anything that could even remotely
have line potential across it unless there's some sort of limiter
(ie: lightbulb) in the way. Intermittent short = kaboom!

And I've recently read that common consumer "pop-up" toasters don't have
three wire cords and grounded cases because people often stick tableware
in them trying to remove a stuck piece of bread. If those metal
implements shorted a toaster element to a grounded case, the element
could burn out.

True, but more importantly, if the toaster is grounded, and you stick
a knife into it to clear out a piece of bread, where's your other
hand? On the toaster!

- Toasted user, not toasted bread.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.