Fuse box-electric H2O heater question

Not my problem but a lady at work was telling the story...
Her husband was away and she was leaving for the weekend. He told her to shutoff the well pump. Also, since the pump we would be off he told her to take out the two fuses for the water heater.
She said that she took out one fuse OK, but while taking out the second fuse it was arcing. Her husband told her that she was supposed to take them out at the same time.
My question is why would there be arcing if one of the fuses is already out?
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Assuming she has a 240V water heater, removing either fuse should cut the power to the water heater. If not, a few thoughts come to mind...
1. There's a short somewhere?
2. She removed the wrong fuse the first time?
3. She has a 120V water heater, so the first fuse isn't in use?
4. Maybe there's a 120V load on the hot water heater circuit (timer, recirculating pump, etc.).
5. Maybe there's a problem with the fusebox and it has nothing to do with the water heater (see #1).
Anthony
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The first fuse should have arced, if the unit was heating at the time. If it didn't and the second one did, I'd guess that one of the elements has broken open and is grounding causing a load

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RayV posted for all of us... I don't top post - see either inline or at bottom.

problem diagnosed and a disconnect installed if he's going to do this nonsense.
--
Tekkie

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