Friend of my dads just called and asked me to come out and check out his hot water tank.

said it blew a fuse the 2wires coming out of the fused disconnect white wire was black and burnt looking and the black wire wasn't hooked up.

so the system had a black wire on the top and white going threw 30amp fuse and on the bottom only the white was hooked up and looked burnt up.

said it has been like this for 20yrs or so he put in a new tank 5yrs ago after the flood in our area.

i looked everything over and replaced the fuses hooked up the black wire and turned on checked out the voltage at all terminal and everything seems fine. and he now has hot water. the wiring in this house is very old and a mess i told him he should get someone in there to fix it.

why wouldn't someone hook up the black wire on this system, they way it was hooked up it had to be running on 120v not 220v?

Quite interesting! You see, there must be a difference of potential for electrons to flow ( thus causing amperage draw). If what you say is true, it's a 110v water heater, and my guess would be that the heating elements were partially grounded ( thus giving you a diff of potential). This is a very unsafe situtation. Was the ground wire hooked to the unit? Or, maybe hooked to the other side of the heating elements? Either way, you really got problems there. Try reading your elements to ground to see if there if continuity ( with the power off of corse, and the other side of the element disconnected) Good luck with your endeavor!

I am unsure on how you had any voltage readings according to the information you posted. Were you testing Hot to Equipment Ground? Thats the only possible way I can see you getting a 120v reading. (unoless its picking a path to ground through the cold water pipe.....yikes) With the other Hot wire not hooked up, I do not see how you could have gotten a 240v reading. You also have some burnt insulation on one of the conductors, which is a sign of a lose connection or overloaded conductor. Sounds like a wiring hazard to me.

never tested the voltage until i hook everything up how it should have been,

either the black wire in the disconnect worked loose after yrs or it was never hooked up. he said he has always had problems with the box and the fuses.

it is a 240v heater and is working correctly now.

he said the black wire in the disconnect has never been hooked up so the white wire must have been overloaded and burnt i don't know. I know its working now and told him his electrical system needs some attention and he should get some one to look at it new wires and service. everything is old style wires and screw in fuses.

Long shot, but if the element(s) were served at 120V, they would operate at ¼ power {E²/R} so for a 4500W element, you’d see 1125W. It would heat the water, but take a lot longer. {I remember removing an ancient 500W storage water heater a few decades ago. The home had been served 2-wire 120V. Guess it was never considered a “fast recovery” unit.}