maybe the light was already on when you plugged it in, causing an arc over, or the plug was wet with water accidently (u were by your fish tank, right?

) and a a arc occured when plugging it in. not really sure, but if you have some doubts about your electrical wiring in your residence, get an electrician to inspect it. also be careful not to overload your electrical circuit, most wiring in home are in the 10 to 15amp range, with all the electrical stuff (tv, stereo, tank, ect..) you might be over doing it, imho!
hth,

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