Heating in wires

Cariboocoot
Cariboocoot Banned Posts: 17,615 ✭✭✭
We often talk about current causing heating in wires. Most people get this concept wrong, thinking that if the wire isn't glowing red hot it isn't heating.

Well here is a picture taken by the mother of a friend of mine, Brenda D Minard of Alberta Canada. It is an ordinary extension cord on the ground with no more current flowing through it than it would typically have. See the effect the heating has?

Comments

  • john p
    john p Solar Expert Posts: 814 ✭✭✭
    Re: Heating in wires

    Just about any wire carrying more than one amp will have some heating happening in the wire.. You may not notice it as the surrounding air can reduce the outside of the insulation effect to almost zero.
    If you have a thermal imager and enter the ceiling of a house with just the normal appliances and lights on you will be amazed how much heating in the wiring is happening and also greater heating inthe switches and power points and plugs.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Heating in wires

    actually john any current will induce heating. it may be distributed in larger wires with smaller currents as the wire acts like a heat sink and the larger surface area of the wire allows more contact area with the ambient air so heating is not as noticeable in that case. there is a point when the wire can't get rid of the heat as fast as the current is producing it and that is dependent on wire size, ambient temps, any insulated wire coverings, and if in an area that does not allow free airflow.