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Why Would A Fuse Blow On An Electric Water Heater?

Over the past 24 hours, the right fuse (of two 15 amp fuses) has blown on the electric water heater. I repalced first time with old but unused 15 amp fuse, then same again today.
There is no hot water whatsoever when one fuse blows.
Over the past two days, we have done loads of laundry at HOT/Cold setting, which does use lots of hot water, but we have done the same many times over the past year.
Water heater is maybe 5 years old? Rental.
Any suspicions as to the cause?

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  1. Comment by Tech Dude
    September 28, 2009 @ 4:17 pm

    The fuse keeps blowing because there is probably a burned out heating element. If you have more than one element, try disconnecting the upper element after removing both fuses (to remove power while you are working on it). Tape the ends of the wires so that they won’t short out or come in contact with you. Then screw the fuses back in to see if the other element(s) produce any heat. If the fuse blows again, maybe it is the lower element that is burned out, but I would first suspect the upper element because elements will burn out if the water level drops.
    Hopefully you will get hot water, but it will take longer to heat up with just one element. If this works, you will have to drain the tank and replace the defective element (after removing the fuses, of course).

  2. Comment by SENSES
    September 28, 2009 @ 4:29 pm

    yo have a shortish in your system.you mite have a lose wire in the system or you extension core.

  3. Comment by hometech
    September 28, 2009 @ 5:12 pm

    disagree with shane on the fire hazzard part. nothing to be worried about as long as you use the proper fuse. the bad element i agree on. about 20$ per element and you might need the tool to take it out. homedepo/lowes sells them both.

  4. Comment by sthrnduf
    September 28, 2009 @ 10:55 pm

    There could be 2 elements in the heater and 1 has gone bad. That is why you are probably blowing just one fuse of the two. Water heaters will have all kinds of build up on the inside of them and your element has been corroded and worn out. this sounds most logical if it just happened all of a sudden.

  5. Comment by Shane H
    September 29, 2009 @ 5:22 am

    i am assuming that you have the old screw in fuse style? well first off if you do i would be considering a service upgrade, take this hint from an electrician. those old style fuse are more a fire hazard then anything. next thing is that you may have a bad heating element. and last thing is that i have not seen a 15 amp hot water tank before. how big is this item and how many Watts is this. to make sure you have the right fuse, take your total watts then divide by 240. that will give you the size breaker you need. PS as in the fire issue that is only if you install the wrong fuse or even a penny are they a fire hazard. but a new panel will have a breaker to reset instead of a fuse, so its a lil cheaper to fix your problem, rather then replace the fuse just rest it.

  6. Comment by andy
    November 30, 2011 @ 10:41 am

    I definately disagree with shane as a electrician myself the majority of water heaters have 3000 watt elements X 2 but only one works at a time so 15 amps is fine the next is 3800 watt elements so you need 20 amps then some of the better tanks have 4500 watt elements so 30 amps so fuse size depending on your wire size you can’t put a 30 amp fuse in if you only have 14 guage wire. As for fuse panels being a fire hazard if you have the right size fuse along with the right size wire there is no fire hazard even if its working hot. fuses are meant to blow 2 ways one due to a short and the other due to heat too much heat the fuse blows when a fuse blows to heat it seperates so look at your fuse and see how it blew if it has seperated you have heat in your panel if it has shorted bad element it is 90 percent of the time the bottom element as it does most of the work if your fuse blow to heat the problem is with the panel

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