derating ques.

[wireman1]

in a 3 phase 208/ 120 system when is the netural wire counted for derating purposes, is it all the time or the type of circuit it is being used on such as resitive, anlog, circuits which contain harmonics etc. ?

 

[iwire]

in a 3 phase 208/ 120 system when is the neutral wire counted for derating purposes, is it all the time or the type of circuit it is being used on such as resitive, anlog, circuits which contain harmonics etc. ?

With that voltage system you count the neutral as a current carrying conductor if:

• If the neutral is one conductor of a two wire circuit. (1 phase, 1 neutral)
  
• If the neutral is one conductor of a three wire circuit. (2 phases, 1 neutral)
  
• If the neutral is one conductor of a four wire circuit. (3 phase, 1 neutral) that the majority of the load in non-linear.

Or we could look at the other way, with a 208Y/120 system the only time we do not have to count the neutral as a current carrying conductor is when the neutral is being used with all three phase conductors and the circuit does not supply a lot of non linear loads.


See 310.15(B)(4)(a), 310.15(B)(4)(b) and 310.15(B)(4)(c).

 

[brother]

in a 3 phase 208/ 120 system when is the netural wire counted for derating purposes, is it all the time or the type of circuit it is being used on such as resitive, anlog, circuits which contain harmonics etc. ?

You need to read 310.15 (B)(4) neutral Conductor

 

[infinity]

You need to read 310.15 (B)(4) neutral Conductor

Or just read Bob's post.

 

[brother]

Or just read Bob's post.

Im a slow typist , he was putting his up while i was still responding.

 

[infinity]

Im a slow typist , he was putting his up while i was still responding.

He has a tendency to do that.:wink:

 

[76nemo]

As if his avatar wasn't intimidating enough? :grin:

 

[iwire]

As if his avatar wasn't intimidating enough? :grin:

It's a front.

Here is my real picture :wink:

 

[SEO]

It's a front.

Here is my real picture :wink:

Pretty smart looking guy.:smile:

 

[peter d]

It's a front.

Here is my real picture :wink:

Believe it or not Bob is actually a pretty nice guy....most of the time.

 

[LarryFine]

It's Milton Milquetoast!

 

[JohnJ0906]

It's a front.

Here is my real picture :wink:

That's a sharp lookin' bow tie there Bob....

 

[acrwc10]

It's a front.

Here is my real picture :wink:

A guy like that scares me a lot more then a guy with a gun. Mister bow tie could be an IRS auditor, or work for some public service office and keep you in suspended animation for an undetermined amount of time. I'm going to hide my head under my pillow now.