i had an unfourtunate experience on my last grow where i was running 2 nft tank and had both pumps running through a double plug extention and have been for years,cut a long story short wrecently we had some hot weather and im a loft grower and the fuse went in the double plug extention and cut of both pumps.when i turned up about 36 hours later my 20 white russians that were 4 weeks into 12/12 were completely fried.