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My tankless home water heater wire is warm

  1. Dec 26, 2011 #1
    Dear Experts

    Happy Holidays everyone!

    I found out that the electric wires of my home water heater gets very warm when I use the heater for normal showering.

    There are 3 wires : Earth , Neutral and Live wires.

    I unscrewed open the power socket and power plug. The wires are melting the connections. The blue and green wires are almost shorted together because the wires have melted to a dangerous level.

    I thought the problem was due to the thin wires used.

    So, I replaced the wires with the thickest gauge wires i could find.

    This time, the wires are not as warm but still quite warm.

    My question is should the wires of water heaters (tankless, instantaneous home heaters, compact in size) be warm?

    My electric water boiler at home boils water to boiling point and yet the wire does not get warm.

    May I know is it the heater that is the problem?

    Please share with me what you think on this problem.

    Best regards
    Ramone
     
  2. jcsd
  3. Dec 26, 2011 #2

    AlephZero

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    If the wiring is getting hot enough to melt the plastic insulation, there is a serious problem here and you need to get a qualified electrician to look at it.

    Possibly, the heater has been connected to the wrong type of house wiring circuit. Even if you "fixed" the problem in the power plug, some other part of the wiring may also be overheating and that could be a serious fire risk.
     
  4. Dec 26, 2011 #3

    Drakkith

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    I'd check and make sure there isn't a partial short or something letting more than the normal current through.
     
  5. Dec 26, 2011 #4

    sophiecentaur

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    "Short Circuits" are rare in house wiring and will usually cause a fuse to blow or circuit breaker to shut off when they do occur.
    One common reason for wires to get hot near a connector is that the connection can be poor (resistive) due to corrosion or loose contact. The current flowing through this resistance will cause energy to be dissipated and this can heat overheat the area of contact and make things worse due to further oxidation. Ten Amps (typical for a water heater) flowing through just One Ohm of resistance will dissipate 100Watts, which can easily melt a screw connector. Your fuses or breakers will not protect you against this kind of fault because the current is not excessive and it is flowing where it is supposed to flow.
    With the mains ISOLATED!!!!!! (turned off at the fuse box) the connections can be checked, cleaned and the screws tightened up. But this is only advisable if you are reasonably competent (and with the permission of the owner of the installation (/parent etc). Once things have got noticeably bad, however, it will normally call for replacement of the cable or the terminal connector, which is a PROFESSIONAL JOB. You'll have to pay up and look large if you want things to be safe.
     
  6. Dec 27, 2011 #5

    Drakkith

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    Can you run that by me again sophie? I don't quite understand what you're saying. Why would the wires get hot if the normal current is running through them? And what does that have to do with the connectors?
     
  7. Dec 27, 2011 #6
    A poor connection can cause heat to be produced at the connector and thermally conducted into the power cord.
     
  8. Dec 27, 2011 #7

    Drakkith

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    It's so obvious now!
     
  9. Dec 27, 2011 #8

    D-C

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    Can an aging element offer less resistance, causing higher current flow..until it trips the breaker? If it's a "U" shape and rusting.....you might just take a look at it if you are so inclined. Your juice might be taking a short cut! And, yes, heat from resistance in a bad connection will conduct up the wire, being less , as you move out from the connector. (I done seen it I tell you!)
     
  10. Jan 7, 2012 #9
    Yes, spot on! That was what happen and after changing to a higher gauge set of wires the wires are still warm after using to shower for about 15 minutes.
     
  11. Jan 7, 2012 #10
    I opened up the box and everything looked normal. no charring or burnt marks.

    I do not know if its typical for such heater wires to be a bit warm when used for about 15 minutes. I turned the temperature button to 8. The highest temperature setting is 9.
     
  12. Jan 7, 2012 #11

    sophiecentaur

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    You can expect wires to get a bit warm when passing their design current. It's just that the temperature is 'acceptable'. Cable of any type is usually specified to operate with a certain amount of space around it and not wrapped tight next to other similar cables. A drum of extension cable, for instance, should always be unwound if you want to pass its maximum current or it can over heat.
    So 'warm' is OK but 'Hot' is not.
     
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