Hello All,
New to the Solar world.
A question that is most likely easy, if you can tell me where I can find this in the regs or ACOP please let me know.
can solar PV cables be run outside in Plastic Conduit? I have heard before it should be metal but I can't seem to find where it states this fact and im under the thought that it can be run in either as long as it provide sufficient protection.
also can AC and DC cables be Run in the same Conduits?
Thanks
Wes
I do not have the code of practice but from the fundamentals of BS 7671 my starting point would be:
Both AC and DC cables should be selected and installed as per the requirements of BS 7671, e.g. selection and erection, external influences, flora and fauna, premature collapse in the event of fire.
On the DC side, each individual conductor must be double insulated, or be extra-low voltage (BS 7671 section 712)
Typically the DC side is not extra-low voltage and so double or reinforced insulation is the protective measure.
Remember that solar PV modules do not produce sufficient fault current for Automatic Disconnection of Supply by fuses, circuit breakers etc, so double insulation is the protective measure used for fault protection
Practically, for most cases this means using the very common PV1-F / H1Z2Z2-K cable.
I see no issue in installing such cable in plastic conduit provided they are installed to minimise the risk of earth faults and short circuits.
I see no reason why you could run AC and DC in the same plastic conduit, unless the ACOP suggests otherwise, unless there is likely to be any harmful interference. (see BS 7671 section 515)
In the majority of solar PV systems the DC and AC are both Band II, low voltage circuits so consideration for segregation would not be required depending on how you read (BS 7671 section 528). You may still decide to coordinate the voltage ratings of your AC and DC cables to suit the highest voltages present.
However, depending what you have in mind, there are BS 7671 requirement for conduit systems.
Multiple circuits are permitted subject to section 528.
I couldn't find the regulation but IIRC there was something regarding consutruction allowing for drawing cables into an assembled conduit system (rather than constructing the conduit around the cables which is probably what you would have to do)
The OSG Appendix E deals with the capacities of conduits and trunking and tells us that no more than 45% of the net cross-sectional area should be filled by cables. This is no doubt reproduced from a guidance note, like GN1.
This capacity requirement is to allow for adequate heat dissapation.
You would need to ensure the CSA of your cables were adaquate for reference method B, taking into consideration grouping factor and any external influences as necessary.
