Where is the value for 'K' found for voltage drop calculations?

[kwired]

May I take this opportunity to sell you on the following formula instead?

VD = ?RID

Which is
VD = 2RID for a 2-wire circuit
VD = √3RID for a 3-phase circuit

It gives almost identical results, just a little quicker - and you don't have to remember the K constant, the resistance values in Table 8 are all you need.

That is a simpler formula and is doing pretty much the same thing - maybe slightly more accurate than the way most of us were taught. Now how do you make someone forget something they have been using for 25+ years?

 

[resistance]

???????Can?t see any post past #20. Does this mean someone blocked me????

 

[lauraj]

The real question is why does the answer use FLA instead of T. 430.248 values?

In a real application you will have the nameplate available also but need to know that you use the tables for just about everything except overload protection.

My guess would be, the question is not a code question about sizing wire for any particular HP motor, but that load that draws 52 amps and happens to be a motor. It's purely a VD calculation for a 52A load.

Also, an easier way to get K from the ch9t8 values is to look at 1000 kcmil Cu or Al ohm/1000' and divide by 1000. I highlight those values in my codebook to make them easy to find.

 

[lauraj]

oops, multiply by 1000, not divide

 

[resistance]

This page has a bug. I can?t move past post #20, unless I post a message

 

[kwired]

This page has a bug. I can?t move past post #20, unless I post a message

I have had that happen a few times before but not for a long time now. Don't know if it is the website or my browser. It is not doing it for this particular thread. You will probably not see this post unless you post something first.

 

[resistance]

I have had that happen a few times before but not for a long time now. Don't know if it is the website or my browser. It is not doing it for this particular thread. You will probably not see this post unless you post something first.

You are right!!! I?m able to move forward?after a couple days. :thumbsup: