GFI blew, 6.5 hrs without power...

[majolo]

So apparently last night at 1am my GFI adapter blew, and I didn't find out till 7:30 this morning. I don't know why it blew. There was no water anywhere around the outlet or any other obvious problem. Checked the tank:
Temp 75.5F (down from 78F)
Ammonia 0
NitrIte 0
NitrAte 10 ppm
All inhabitants were behaving normally.
I reset the GFI and had to go to work. I'm holding off on feeding until I'm confident my biofilter is ok.

My main concern is what caused it to blow. It is a Shockbuster brand 5-outler GFI adapter. Plugged in are:
Visitherm Stealth 250W heater
Satellite 2x65W pc lights
AC 70 HOB filter
Fluval 2 internal filter (maturing for a planned second tank).

I've only had it trip once before, this weekend during a PWC; I assumed I had splashed water somewhere. Checked that everything was dry and reset and all was well.

Any ideas?

Edit: Here's an update. All still looks well in the tank. On the advice of an electrically-savvy friend, I picked up a receptacle tester at a hardware store, and it turns out my outlets were not correctly grounded.
Some electrician somewhere (not to mention my house inspector when I bought the place) has some explaining to do!

 

[tropicalfish]

Lol!! I am glad you found the cause...
Grounding is VERY important... seems like someone indeed has something to explain!

 

[rhetor]

Grounding is one of those things that are easy to pass off as not necessary when building the house.

A quality contractor, electrician, or inspector knows that proper grounds are ABSOLUTELY NECESSARY!

glad you found the problem though instead of buying another strip to find it does the same thing!