Current Transformer (CT) Secondary Wiring

c_picard

Senior Member
Location
USA
Does the CT secondary wiring need to be rated 600V for installation in a 120/240V panel?

Is this considered Class 1 wiring subject to Article 725? Or does 300.3(C) cover this sufficiently?

I ask because 725 point to 450, but CTs are explicitly excluded from the scope.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I think one can make a good argument that CTs circuits are indeed class 1 circuits.

Having said that, there does not seem to be an exception for the required OCPD in the transformer circuit found in article 725.
 

c_picard

Senior Member
Location
USA
Thanks. I don't think I could make a decent case against your Class 1 argument.

Overcurrent protection is another item that points to 450.

725.45(D) > 450.3(B) > Table 450.3(B) = 125% of primary current?

But 450.1 Exception No. 1 excludes CTs altogether.

I think the Code might be broken, hand me a sledgehammer.
 
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