Double insulated solar wires in wireways

[Isetech]

Another hot topic, which requires urgent attention. I am not going to go into detail now, just point out the confusion.

Do you just run the wires on the surface?

Do you run the red and black in the same conduit with the earth wire?

Do you have to install steel conduit.

IF you in the group who says you cannot install both the red and black wire in the same PVC conduit, then I ask this question do you install additional trunking to separate the red and black when it gets to the inverter trunking?

Lets spit it out and at least get a basic guideline for people to use.

While we are about it, try clear up the lithium propaganda

[GCE]

There are regulations out on wiring of PV strings - SANS 60364-7-712

[Isetech]

Deleted, not the correct document.

The correct document is 70 pages

[Isetech]

An interesting article.

https://portal.segensolar.co.za/reseller/docs/Wiring%20of%20Hybrid%20Solar%20PV%20systems%2028%20Feb%202023%20v2.pdf

[Isetech]

Basically the IEC code.

IEC 60364-7-712:2017

[Isetech]

Reference to SANS 60364-7-712:2018Edition 2

712.542.101 Functional earthing

For mechanical protection, the minimum cross-sectional area for a functional earthing
conductor is 4 mm2 copper or equivalent.

[Isetech]

Refence to: SANS 60364-7-712:2018Edition 2


I see a lot of comments about sizing of conductors, take note in red.

Take note of the conductor sizes in red.




712.534.4.10 Connecting conductors of SPDs


Add the following:


• When SPDs are installed on both AC and DC sides of the invertor in separate
switchboards, it is recommended to minimize the distance between those switchboards.

• For DC SPD connections to the main earthing terminal the conductors shall have a
minimum cross section of 6 mm2 copper or equivalent for Class II tested SPDs and
16 mm2 copper or equivalent for Class I tested SPDs.

[Isetech]

Take note:

712.514.107 Documentation


Documentation shall be provided in accordance with IEC 62446-1.
A set of operational instructions for the insulation fault alarm referred to in 712.531.3.101.3
shall be provided to the PV installation owner, which explains the need for immediate action
to investigate and to correct the fault.

[Isetech]

This is interesting, if you use red and black wires for AC and DC, then the DC cable should have additional labels, this could be why you see some people fit labels to the conduit.

712.514.2 Wiring systems


Add the following:
The identification of AC and DC circuits shall be such that they are clearly distinguishable
from each other (e.g. by labels or different coloured cables).

[Isetech]

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.

[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.