NEC Voltage Drop

I would calculate for each and submit both on my homework assignment.

100%

Friend,

As Tornado has said, the NEC uses 100% of the FLC (full load current). The NEC uses 125% for calculations regarding the ampacity of a circuit and its overcurrent protection device for a continuous load (defined as a load that is on for 3 or more hours). Remember, however, that the NEC specifies a minimum standard of design/installation and encourages workers to exceed this standard. Therefore a calculation using 125% of the FLC will result in a lower energy loss balanced against a higher cost of the installation, along with better operation of the attached load.

--JMM

Why would you consider 125% ?

http://www.mikeholt.com/technnical-voltage-drop-calculations-part-one.php

http://www.southwire.com/support/voltage-drop-calculator.htm

One reason would be to ensure that selective-tripping is functional. Especially when nearly identical trip-points are in series and starting currents/voltages exceed the limits of rated values. Also, there are two different ways to look at it. One from the supply side, and one from the load side. Sometimes I get objections when I say that you can use fuses for two different reasons: One to protect the load, and one to protect the supply. They usually think that if a fuse/breaker trips, that the whole circuit is protected because ALL of the current stops. But the problem is that, if there is a partial fault in the load, it could damage the load-side circuits without tripping the supply-side protection. Therefore, the load-side protection should be closer to the normal values of the load, while the supply-side protection should be closer to the capacity of the supply. Sometimes this is not a factor with selective-tripping, and gets forgotten. Also, having a larger safety margin might be desirable (for whatever reason), even if it's not needed. What's required/optimal/safe/over-kill is a judgement call. But whatever call is made, it still has to function properly within the larger system (which may or may not be adjustable).

I don't know the current value, what is it presently?

If it is 100% FLC, I would use that. If 130% FLC, I would take off running.

Really? Maybe I misunderstood the whole purpose of the question. I thought it was just to get valid info to.... (???whatever). How could having valid info be "take off running" worthy? Am I missing something?

You missed my joke.

Oh. I never really had a keen sense of humor. I tried to get it calibrated once, but they thought I was joking.

right...

current vs. present...

got it now?

Yes, I currently got it at present. Now, I just have to put it in a safe place for tomorrow.

100%

Usually, you have to check the minimum voltage in 2 situations:

1) at rated current [preferable 100%]

The minimum voltage for continuous function has to be as per NEMA MG1 [or IEC 60034-1].

2) start current

The minimum voltage for start has to assure a minimum torque as required.

If the load inertia it is in limits recommended by NEMA [or IEC] then a minimum 80% of motor rated voltage has to be present at motor terminals [for up to 100 kW induction motor] at start.