Thermocouple Circuits

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KRL

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What is a thermocouple circuit classified as, class II or III? Is it possible to re-classify a thermocouple circuit to class I utilizing Type TC 600 volt thermocouple extension cable, thus allowing the thermocouple cable to run in the same cable tray with other class I circuits?
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I think reclassified circuits have to have overcurrent protection devices added to them. I'm not sure that I would want to put a circuit breaker or a fuse in a thermocouple circuit.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
article 725 where forum members fear to tread. :)

It appears to me that article 725.121 (A) makes thermocouple circuits automatically a class 2 circuit.

as far as reclassifying class 2 circuits, take a look at 725.130 (A) exception #2.
 

GoldDigger

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Placerville, CA, USA
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Retired PV System Designer
I don't think reclassifying a thermocouple circuit would work since thermocouple extension wire is not a Chapter 3 wire type.
Even if it was allowed I would not want to run millivolt level DC signals alongside AC power wires.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I don't think reclassifying a thermocouple circuit would work since thermocouple extension wire is not a Chapter 3 wire type.
Even if it was allowed I would not want to run millivolt level DC signals alongside AC power wires.

I didn't say it was a good idea.

I think you can get 600V rated thermocouple type tray cable.
 
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