They run on 24vdc, and even if they had a voltage leak it would not hurt you, the fish or the corals. I've proven on the WP-40 forum that you can take a 24vdc transformer and stick the plug directly into saltwater and not even get a reading to ground. I stuck my hand in the water and grounded myself and still nothing. I then left the plug submerged in the water and it took approximately 12 minutes for it to take out the 2 amp fuse. I used a 24vdc 75va transformer for the test. I've heard a lot of grief from the MP fanboys about how these cheap pumps are going to electrocute somebody or burn down the house. I have 3 WP-40's and 3 WP-25's running in my tanks, since the day they were introduced and have yet to have any problems. I am just getting ready to purchase a couple of WP-60's. For the money, these pumps can't be beat!