Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Effect of voltage on resistance wire life expectancy?

  1. Jul 14, 2016 #1
    I am using a 30kW air heater which is using resistance wire. I am not exactly sure what type of wire it is and hope this will not be an issue in answering this question.

    The heater is rated at 380V and 45amps(max)...my supply is 415VAC (+ 6% and - 10%) and 45amps.

    Any idea if this extra voltage will effect the life expectancy of the element?

  2. jcsd
  3. Jul 14, 2016 #2


    User Avatar
    Gold Member

    Probably bad - if the rating of 380 and the supply of 415 are apples-to-apples numbers. The power dissipated in the element is V^2/R, so the element will be hotter than the heater design anticipates. This is dangerous to do with a heater, imo.

    If there is a fan in the heater, the fan motor is potentially going to react poorly to being over-voltaged.
  4. Jul 14, 2016 #3


    Staff: Mentor

    http://www.frankshospitalworkshop.com/electronics/training_course/images/bulbs_life_expectancy1.jpg [Broken]

    Incandescent bulbs also heat wires, so this curve should be relevant. Pay attention to what @Grinkle said about safety, especially with so much power involved. you could burn the place down.
    Last edited by a moderator: May 8, 2017
  5. Jul 14, 2016 #4
    Would a step down transformer be an option?
  6. Jul 14, 2016 #5


    Staff: Mentor

    A transformer would work, but it might be hard to find and expensive. If this is temporary and not permanent, Renting a 415v heater might be the cheapest solution.
  7. Jul 14, 2016 #6
    Yeah, I just had a quick look and they are extremely expensive...more than the heater itself! I am having trouble sourcing an off-the-shelf air heater which can provide the output temperature I need (at least 750°C at an air flow rate of 40-55 SCFM).
  8. Jul 14, 2016 #7


    Staff: Mentor

    How about an electrician to get you 380v service?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted