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guyw wrote: As John correctly points out, my numbers and formulas are OK, but my description of the bulb lighting process is almost entirely backwards. I blame early morning no caffeine syndrome. A cold light bulb has very little resistance. As it warms and lights, the resistance goes up, reducing the current flow. If not, the process would go into thermal runaway, and the filament would burn up. This means however, that initially a large current will flow, decreasing as the bulb warms up. It is this "inrush" current that risks the lighting of an e-match. An LED does not act this way, and 10ma or so of current is what it draws when it is on, making it initiator safe.
BTW... I seem to recall reading somewhere that if you replace a bulb with an LED, your also need to add a resistor of the appropriate "ohmage"... Is that correct?