Wire termination temperature mismatch 1

[thinker]

I need to make connection to equipment with flying leads (special high temp wires rated for 150 deg.C ampacity).If I need to use NEC 75 deg.C rated wires connected to that equipment, what would be the best way to reduce temperature to 75C level? May be use a piece of copper bar between those two wires and trying to estimate the temperature gradient (decline) along the bar length? Please advise.

 

[MacGyverS2000]

I'm confused. Supposedly the 150C wire is rated so high because it needs to carry a lot of current at a lower-than-normal gauge for a certain distance. At some point, however, it has to attach to wire of some other gauge... so what would the bus bar gain you? Make the attachment wire of a thicker gauge, allowing it to carry the same current but at 75C.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[thinker]

Thanks for reply, Dan. A bit more details. Under normal operating conditions, these 150C wires are terminated to the equipment also rated for 150C operations. We need to test a part of this system, so we need a transition to lower temp rated wires. The question is about temperature rating of the termination point. I do not beleive I can connect at one point (say, stud) the 150C running hot wire, and a larger size (for the same ampacity) 75C rated wire(or wires.

 

[IRstuff]

??? If you're running this to equipment not rated for 150ºC, then the 150ºC rated wires MUST at some point in time drop in temperature. I would think that a couple of feet of wire outside of the 150ºC environment would be enough to drop down the wire temperature to the desired level.

TTFN

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[MacGyverS2000]

What IR said... just because the wire is rated for 150C doesn't mean it runs at that temp the entire way. I mistakenly was under the impression the wire would get up to 150C due to a smaller than typical gauge... now I realize it's the insulation's rating. At some point outside of the equipment the wire will be subject to more normal temps.

Dan - Owner

http://www.Hi-TecDesigns.com