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Old April 16th 08, 07:54 AM posted to uk.railway,uk.rec.subterranea,uk.transport.london
Clive[_2_] Clive[_2_] is offline
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First recorded activity at LondonBanter: Apr 2008
Posts: 5
Default Crossing London tube tracks


"David Hansen" wrote in message
...
On Tue, 15 Apr 2008 18:18:08 +0100 someone who may be "Jeff"
wrote this:-

The physical size of the fuse IS important when you are considering
spark-gaps etc, which is what caused the dramatic failure in this case.

Incorrect. What is important in this respect is the breaking
capacity of the fuse. Different designs of fuse, with the same
physical dimensions, are able to reliably break different currents.



Not incorrect, some fuses have fillers in the tube to help prevent arcing

at
EHT voltages.


Incorrect. The "fillers" (and indeed the nature of the fuse element)
are one of the determinants of the breaking capacity.


Incorrect, filling a fuse body with sand provides additional protection
against arcing in an overcurrent situation.