Solar cable runs from roof space to plant room on ground floor.

[jimseng]

Hello.

I am planning on bringing the 2 strings +/- cabling through the roof into my loft space. It is an in roof system and I believe there is room to bring the cables in via two cable entry housings mounted underneath the last panels in the strings. I am planning on using PV cabling with MC4 connections to the last solar panels in the strings, through the roof via the entry housing into a connection box. I think it would be sensible to put the SPDs for the solar in the connection box, two breakers and then on to the ground floor plant room to the inverter.

In the loft space the cable run will be in conduit. Does it need to be metal or can I use plastic?

 

My house, which is still in build has a 45mm service void on top of the insulation membrane. Are there any specific rules about running the cabling through that, i.e. further mechanical protection?

I am probably going to be running this cable in way before the ac first fix happens.

[BotusBuild]

Plastic conduit will be fine.

Is the 45mm void just under the roof tiles? I would put the cable in conduit for extra protection.

[jimseng]

Quote

Is the 45mm void just under the roof tiles?

I was referring to the whole house having a 45mm  battened service void behind the plasterboard  for all electrics and plumbing. I'm asking what would be the correct method for getting two runs down to the plant room once it exits the loft space. Is it adequate to follow safe zones in the service void down two floors or am I expected to afford extra mechanical protection for the solar cable.

 

[JohnMo]

I would bring the cables to a multi pole DC isolator on the outside of the house, for ease of access in case of a fire. Then run the rest of the DC to your inverter.

 

Run cables in service void but I would want something to you or someone else drilling a holes later and hitting a DC cable. So in save zone with metallic shield so something like 

https://www.screwfix.com/p/deta-tte-37mm-galvanised-steel-channel-2m/826VT?tc=TA5&gclsrc=aw.ds&gad_source=1&gad_campaignid=22599672207&gbraid=0AAAAAD8IdPyi10Bx2zrVz5Z9Lr6xcezkw&gclid=CjwKCAiA_orJBhBNEiwABkdmjHstK7DySAtkOoGd1V-4dnj9I9QLc64xIKDU339IXlACKlvaonv5AxoChkYQAvD_BwE

[Nickfromwales]

The regs have changed a fair bit here for DC runs in domestic dwellings, so on the last one (summer '24) I ran galv conduit internally to convey the 2x red and 2x black 4mm DC feeds from the roof to the rotary isolators in the GF plant space. Best to double-check with an up-to-date installer. If you need one let me know as I have a very good solar chap who works nationwide.

[jimseng]

Quote

The regs have changed a fair bit here for DC runs in domestic dwellings

This may be a stupid question but can anyone guide me to where I can find these regs?

[Dillsue]

Lots of the wiring regs are open to interpretation and judgement of the spark/designer of the wiring system so if your expecting/wanting the spark who wires your house to include the DC cabling in his installation cert then probably best to take their advice on how they'd like to see the DC cables installed??