Anonymous asked in Science & MathematicsEngineering · 1 month ago

How hot does it get inside EMT or Thinwall conduit facing the sun mid day?

What is the temperature inside thinwall electrical metal tubing when it is facing the sun vertically and overfilled on a hot 108 Degree Fahrenheit temperature day roughly.


To make it simpler how hot does it get inside thinwall emt for your power wires or cable wires when EMT faces the sun and its 100 degrees outside.   A garden hose in the sun will burn your hands and the water is hot.   

7 Answers

  • Anonymous
    1 month ago

    What COLOR is the EMT? 

    What is the ambient temperature?

    What size is the EMT?

    Describe the quantity and size of the wires inside the EMT.

    How much current is flowing through the wires inside the EMT?

  • 1 month ago

    If you are asking an engineering question, I'm concerned that the conduit is overfilled.  If you're in the USA, such an installation will never pass inspection.

    If you are putting up photovoltaic, it's a good idea to take a look at article 290 of the NEC, as well as the articles on wire gauge.  Part of the temperature inside the conduit will be determined by how much current is flowing through the wires.  And also note that conduit is inherently considered a wet location.

    Where I live, 70 degrees C is a reasonable assumption for the peak temperature of conduit outdoors.  So one might be tempted to think that for carrying 18 amps, #12 THHN wire is enough - after all rated for 20 amps, right?  But the wire is derated to 0.58 ampacity at that temperature, and there are also other safety factors that are required depending on the case.  Since it was in conduit, I ended up having to use #8 THWN-2 wire.  Outside of conduit (if your location allows that), #10 wire would have been enough.

    Some of these calculations are in the file calcuations.txt at

    Also note that inspectors generally are looking for standard practices.  If you are putting in, say, an air conditioner, they will look for the type and gauge of wire that they normally see local electricians use on that kind of circuit.  Same for photovoltaic.  If you use something unusual, you will need to be prepared to explain your choice.

    The actual temperature inside the conduit will vary, of course, depending on air temperature, shade, sun angle, and a variety of factors.  If the conduit is vertical, it's possible that the top will be much hotter than the bottom.

  • 1 month ago


  • 1 month ago

    ~150 degrees F=

    65.5 deg C.

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  • 1 month ago

    I take it the wire is insulated

    Attachment image
  • 1 month ago

    Found this...

    I'm not sure it addresses your question directly, but it does give some guidelines. 

  • Mike
    Lv 7
    1 month ago

    This has nothing to do with Astronomy.

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