Double insulated solar wires in wireways

[Isetech]

712.521.103 Wiring loops


To reduce the magnitude of transient overvoltages, the PV array wiring shall be laid in such a
way that the area of conductive loops is minimum (e.g. by laying cables in parallel as shown
in Figure 712.10)

[Justloadit]

Page 36 clears up the confusion with regards to solar wires in PVC/metallic wireways.

If you decide to install single insulated cable in PVC conduit, it must be installed in a separate conduit, however

IF you install double insulated PV specific cable, it should be installed inside the same PVC or metallic conduit.

In fact as you read the document, you will see that every precaution should be taken not to separate the conductors to prevent other issues.

The positive and negative should be installed as close as practical at all times, even between the panels, jumping for the top to the bottom string with only one conductors is not advisable.

Lets get the fact correct.

There is a reason to keep the 2 DC wires close as possible(parallel), being DC, there is a magnetic field created around the wire if it is individual. Having both close to each other cancels this magnetic field.

Understanding that the wire could be similar to a wire in a generator, it can induce voltages in any other wire running close. Now in most cases there is a a high DC current flowing, and high lights how strong these magnetic fields become, now imagine the same thought with respect to battery supplied cables pushing +100A.

[Isetech]

I have seen installations where the panel wiring goes along the top pos. to neg. around the outside, then down to the next string and along the bottom and back up to top, creating a nice big loop.

Some installations, every second panel is flipped also creating anice big open loop.

Then you get the one where the pos. is on the left and the neg. is on the right of the string.

But hey people learning as they go, there is still a lot to learn and unfortunately the customer is going to sit with the problems.

There is a reason to keep the 2 DC wires close as possible(parallel), being DC, there is a magnetic field created around the wire if it is individual. Having both close to each other cancels this magnetic field.

Understanding that the wire could be similar to a wire in a generator, it can induce voltages in any other wire running close. Now in most cases there is a a high DC current flowing, and high lights how strong these magnetic fields become, now imagine the same thought with respect to battery supplied cables pushing +100A.