Working in our en-suite drilling a hole for an alarm cable through a joist under the floor boards, I accidentally clipped a bit of microbore feeding the en-suite radiator, with the teeth around the outside of the drill chuck. Bit of a spark, and water jet out the pipe. I runs down stairs to grab some tape to stem the water flow, and back up, ignoring Mrs Midge who sensed something was wrong (I don't normally move at that sort of speed!), until I'd got the situation under control.
When I explained (somewhat bemused, as I didn't clip it that hard at all and microbore bends easily anyway), Mrs Midge said a few seconds before I came running downstairs, she could have sworn the lights dimmed for a fraction of a second.
I couldn't very well undo my taped repair, so I looked at the drill chuck instead - where there was a tiny burnt spot on it. Then I checked the drill bit, and there was a tiny nick out of the cutting edge of that. Then the penny dropped.
Why, when sparks occur as a result of bits being ground OFF steel, would ANY spark occur at all, when something like a hardened steel drill chuck hits something soft and non ferrous like a bit of microbore?
The answer had to be that what I'd seen was an ARC, and not a SPARK.
I was drilling the hole through the joist without checking what was behind, as there was no power within several feet. Or so I thought. However, down in the hall below was a big blanket box, hiding a long forgotten power socket. The house is built on a concrete raft, so the power drops down from above to the ground floor - and I'd drilled just up the edge of a power cable, enough to touch live with the drill bit.
When I finally took the tape off the microbore, there was a perfect little hole about 2mm diameter melted through it. Kept the tiny section of pipe in my toolbox for years afterwards to remind me, and had the old fuse box changed for a modern consumer unit in due course (it didn't blow the fuse).
When I explained (somewhat bemused, as I didn't clip it that hard at all and microbore bends easily anyway), Mrs Midge said a few seconds before I came running downstairs, she could have sworn the lights dimmed for a fraction of a second.
I couldn't very well undo my taped repair, so I looked at the drill chuck instead - where there was a tiny burnt spot on it. Then I checked the drill bit, and there was a tiny nick out of the cutting edge of that. Then the penny dropped.
Why, when sparks occur as a result of bits being ground OFF steel, would ANY spark occur at all, when something like a hardened steel drill chuck hits something soft and non ferrous like a bit of microbore?
The answer had to be that what I'd seen was an ARC, and not a SPARK.
I was drilling the hole through the joist without checking what was behind, as there was no power within several feet. Or so I thought. However, down in the hall below was a big blanket box, hiding a long forgotten power socket. The house is built on a concrete raft, so the power drops down from above to the ground floor - and I'd drilled just up the edge of a power cable, enough to touch live with the drill bit.
When I finally took the tape off the microbore, there was a perfect little hole about 2mm diameter melted through it. Kept the tiny section of pipe in my toolbox for years afterwards to remind me, and had the old fuse box changed for a modern consumer unit in due course (it didn't blow the fuse).
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