Neutral on a DC circuit

[mooreaaryan]

I am installing a DC panel board. The prints have a neutral in the drawing and the crew has pulled a neutral. I am curious what the neutral is actually doing? Is it just an effective ground fault path or it having another operational function that is required for DC. 600amp DC breakers

 

[Dsg319]

Never heard of a neutral in a DC circuit.

Are they possibly mistaken it for a EGC. “Equipment grounding conductor”

 

[mooreaaryan]

They have the EGC separately id on drawing.

 

[GoldDigger]

The only way there could be an NEC neutral on a DC circuit would be if the DC source has +V and -V voltages with respect to the "neutral"
That neutral may or may not be a grounded conductor.
An example would be supplying +12 and -12, where some equipment uses one or the other or both rather than only the line-to-line 24V.

 

[tom baker]

Edison used neutrals and developed the three wire ckt.
Perhaps on your application it’s a grounded DC conductor.

 

[LarryFine]

The only way there could be an NEC neutral on a DC circuit would be if the DC source has +V and -V voltages with respect to the "neutral"
That neutral may or may not be a grounded conductor.
An example would be supplying +12 and -12, where some equipment uses one or the other or both rather than only the line-to-line 24V.

Exactamundo.

 

[gar]

221031-2143 EDT

Edison invented the concept of a neutral wire, probably about 1880. And for a very good reason. Think.

You need to understand what Edison did and accomplished in a matter of just a couple years. Going from no parallel electrical distribution ( meaning creating a system to provide small incrementally switched lights ), to easily switched lights or other loads, a parallel system. At the time, 1879, this meant he had to develop a DC system. He had to create practical components for all the different parts of such a system.

There was was no way to provide low cost DC voltage level translation. So low impedance distribution was needed.

I believe that Edison determined that at that time the maximum practical bulb voltage would be around 100 to 120 V.

To reduce copper wire distribution costs for a given total load he invented the three wire distribution system. Yes, this was the +/- and neutral system.

.

 

[jaggedben]

A neutral in a DC system works essentially the same as in an AC system, except that since there is no vector math the concept can't really be extended beyond 3-wire systems. The neutral will carry current for unbalanced line-to-neutral loads just like in AC systems. If polarity matters to the load you'll likely have to pay more attention to that than to the usual ungrounded vs. grounded terminal designations.

250.162(B) requires the neutral to be grounded.

 

[jaggedben]

Note also the particular requirements in 250.164.