Effect of voltage on resistance wire life expectancy?

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Discussion Overview

The discussion revolves around the impact of operating a resistance wire heater rated for 380V on a supply voltage of 415VAC, specifically concerning the life expectancy of the heating element and safety implications. Participants explore potential solutions and alternatives to address the voltage discrepancy.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant expresses concern that operating the heater at 415V, which exceeds its rated voltage of 380V, could lead to increased power dissipation and overheating of the element, potentially reducing its life expectancy.
  • Another participant highlights the safety risks associated with the higher voltage, suggesting that the heater may operate hotter than designed, which could be dangerous.
  • A reference to a curve related to incandescent bulb life expectancy is provided, implying that similar principles may apply to the resistance wire in the heater.
  • One participant proposes the idea of using a step-down transformer to reduce the voltage to the rated level.
  • Another participant acknowledges that while a transformer could work, it may be difficult to find and potentially expensive, suggesting renting a 415V heater as a more cost-effective temporary solution.
  • A participant mentions the high cost of transformers and the difficulty in sourcing a suitable air heater that meets specific temperature and airflow requirements.
  • One suggestion is made to consult an electrician to obtain a 380V service instead of relying on the current supply.

Areas of Agreement / Disagreement

Participants generally express concern about the implications of operating the heater at a higher voltage, but there is no consensus on the best solution to the problem. Multiple competing views regarding the safety and practicality of different approaches remain.

Contextual Notes

Participants note the potential for increased heat and safety risks without resolving the specific mathematical implications of the voltage increase on the resistance wire's life expectancy.

Who May Find This Useful

This discussion may be of interest to individuals dealing with electrical heating systems, those considering modifications to existing equipment, or anyone exploring the effects of voltage on resistance wire performance and safety.

kyle pender
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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?

Thanks
 
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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.
 
http://www.frankshospitalworkshop.com/electronics/training_course/images/bulbs_life_expectancy1.jpg

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.
 
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Would a step down transformer be an option?
 
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.
 
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).
 
How about an electrician to get you 380v service?
 

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