dc wireing

[mcgovern65]

is there a chart to show what size wire to use for dc power (pv, wind.gen.) or is it the same as ac ?

 

[jbt260]

It's the same as AC.

 

[K8MHZ]

It's the same as AC.

To be safe, yes. In reality they can be smaller if the runs are short enough. Just look at the wire sizes used in cars.

 

[mivey]

To be safe, yes. In reality they can be smaller if the runs are short enough. Just look at the wire sizes used in cars.

But we have to comply with the NEC.

 

[brian john]

Hey conductors we utilize in AC wiring can carry higher amperage in certain installations than we typically place on them per the NEC. But we are constrained by the NEC.

 

[ike5547]

In reality they can be smaller if the runs are short enough.

That statement can be generalized to include AC circuits too.

 

[dereckbc]

Not so fast guys. While the NEC is the minimum requirement, that does not mean it is good choice for low voltage DC applications.

In low voltages used in solar, wind, telecommunications, etc you cannot afford the luxury of large voltage drops like you can with higher votages.

We use tables based on on current and distance to keep th evoltage drop to less than 1/2-volt on 12 VDC, 1 @ 24, and 2 @ 48 systems. This pretty much neans the NEC tables are useless which is not a problem since the size will always be much larger unless we are talking about really short distances.

I would advise using the following formula to base the wire size

CM= (22.2 x I x D)/VD

Where:

CM = Minimum Circular Mills
I = Maximum load current in Amps
D = 1-way distance
VD = Maximum voltage drop allowed

Once you calculated the CM cross check with NEC 310 to be sure the wire size is at least equal or greater. Rarely will it ever be smaller than th eNEC requires.