Voltage Drop

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MyBeardAndMe

Senior Member
Location
USA
Occupation
EE
I was reading over the voltage drop publication seen here: http://www.mikeholt.com/technical.php?id=technicalvoltagedrop1

Midway down the page after the first example is this:

"Author?s Comment: The 5.3% voltage drop for the above branch circuit exceeds the NEC?s recommendations of 3%, but it does not violate the NEC unless the 16 ampere load is rated less than 113.6 volts [110-3(b)]."

This example was in reference to a 120V rated load. So, the author is saying that if the load was rated for 110V, it would violate the NEC?

Or for a motor rated 460V, if your calculation says the voltage drop from a 480V source would give 465V at the motor terminals, you are violating the NEC according to the author's statement...

That just doesn't make sense to me. One, it is a calculation and two, voltage varies throughout the day.

Also, I believe he was intending to reference NEC 110.4, but I'm not sure.
 

raider1

Senior Member
Staff member
Location
Logan, Utah
I believe what Mike is referring to is that if a piece of equipment is listed to run at a specific voltage then if the voltage is lower than the equipment is rated to run at it would violate 110.3(B) which requires we follow all instructions included witht he listed and label piece of equipment.

Chris
 

MyBeardAndMe

Senior Member
Location
USA
Occupation
EE
By the way he words it, I read it as you violate the NEC if the operating voltage is higher than the rated voltage of the piece of equipment. I think you just stated the opposite.
 
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