Overall Change.

Voltage levels are changing in many areas of the NEC. Question: Would the fuse on the left be suitable in a PV source circuit where 15 PV modules were wired in series, if each module had an open circuit voltage of 42 volts?
Click to Enlarge
Voltage levels are changing in many areas of the NEC. Question: Would the fuse on the left be suitable in a PV source circuit where 15 PV modules were wired in series, if each module had an open circuit voltage of 42 volts?

Code Change Summary: An overall NEC change to increase voltage levels occurred throughout many code articles.

Since the 1920 NEC, the information in the beginning of most NEC articles applied to installations of 600 volts or less and the later part of most code articles applied to installations over 600 volts.

Now, the beginning of most articles will apply to installations of 1000 volts or less and the later part of most code articles will apply to installations over 1000 volts.

This change is due to newer technologies such as wind electrical generation systems and photovoltaic systems that can operate well over 600 volts.

The voltage change occurred in many articles but not all. Making the voltage change in all articles would have resulted in a complete rewrite of some NEC articles as well as many manufacturers going back to the drawing board to make equipment compatible with the new voltage threshold.

Below is a preview of the NEC.  See the actual NEC text at NFPA.ORG for the complete code section. Once there, click on the “free access” tab and select the applicable year of NFPA 70 (National Electrical code).

2014 Code Language:

240.1 Scope. Parts I through VII of this article provide the general requirements for overcurrent protection and overcurrent protective devices not more than 600 1000 volts, nominal. Part VIII covers overcurrent protection for those portions of supervised industrial installations operating at voltages of not more than 600 1000 volts, nominal. Part IX covers overcurrent protection over 600 1000 volts, nominal.

 

Did You Like This? Let Us Know With A Like! Thanks!

Overall Change.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Which of the following does Part I of NEC Article 240 apply to?

A: Overcurrent devices NOT more than 600 volts nominal.
B: Overcurrent devices NOT more than 1000 volts nominal.
C: Overcurrent devices NOT more than 480 volts nominal.
D: Overcurrent devices NOT more than 240 volts nominal.
Please register or sign in for electrical continuing education courses.

If you were already signed in, your session probably expired, please sign back in.