SWA cable alongside cat5e

I am considering a quote for a 6kw solar pv ground array with battery storage 2 x 4.5 kw packs. The installer had requested I install 16 mm2 SWA from the array to the house a distance of 70m . I have already installed the ducting so would not be an issue. I have also been asked to run Cat5e cable with it . When I queried this I was told it was ok. I have always believed that network cable is ok crossing a mains supply but not in parallel. Is SWA different .

Any thoughts?

Thank you

My only thought is 70M is a hell of a long way for Cat5 assuming it is actually being used for Ethernet?

I'd say the SWA  armouring would screen  any mains interference ,  buy I know sod all , see what others say . 

Remembering that  in 3 Comp.  dado trunking  Cat5  runs parallel  usually  with a 240V  ring main  wired in 6491X  with just a PVC separator . with no ill effects.

My fibre broadband comes into the house at 50mbs. I have an extension from there to an office in my workshop which happens to be about 70 m in external grade cat5e and get no loss of speed in the office. I am unclear what the cat 5e is for but think it is to do with monitoring the performance of the panels. It is a valid point that in dado trunking the cate 5 is close to 240 v mains. I went to great pains when I wired my house to ensure that if I ran parallel to mains then I was at least 300mm away.

I would be trying to get advice from a CAT5 cable company (manufacturer, not wholesaler) before quoting the customer...

The SWA armour should be earthed, thus, should not give issue with “noise” from the mains, but, this is not guaranteed, and depends on the current, and the actual lay of the armour in the cable.

The “lay” depends on the way the cable is made, wound, unwound, & how many times this is done, and how it is installed in the duct.

You can get SWA Cat5E and I have installed this in ducts with (relatively) high current 3ph mains SWA without issue, and, over the distances you are looking at.

Whatever you do, do NOT use “normal” Cat5E, use at least duct grade.

I would think the biggest risk with long lengths of data cable is induced voltage during electric storms.

This used to regularly "kill" the links on a big industrial site I worked on.

Geoff1946 said:

I would think the biggest risk with long lengths of data cable is induced voltage during electric storms.

This used to regularly "kill" the links on a big industrial site I worked on.

Click to expand...

Hence the requirement in the 18th for surge protection...

I have installed  a very similar PV array. The Cat 5 is for monitoring the inverter, rather than run a  cable I used Ethernet over Power adaptors (install a socket both ends) which works absolutely fine. Which end are the batteries? I ask becuase if the cat5 is for the battery charge controller, then I'm not sure the EoP adaptors will work - the cabl will be for a meter or Amp Clamp that monitors energy flow at the meter tails.

My thanks for the replies some good info there. Learning all the time. Don't think the installer is interested have requested 5 times to see the array he has installed at his place but does not get back to me. He was pushing on an open door. Now got a similar quote but for a smaller battery (4.8 kw) . This installer would prefer to have the inverter indoors which means running the 70 m of cable as DC . From previous postings it seems that DC underground is not a good idea. I went to see an install he had done and had he run DC to an outbuilding which housed the inverter. There was no need for a data cable with this arrangement. Interestingly the underground cable in a duct was white /transparent  in colour at first I had though it had been put into a reinforced PVC hose but seemingly it is a special very flexible cable that he uses to ensure he has no problems pulling through ducting. Does anyone know what cable spec this would be? He said that 10 sq mm cable would suffice whereas the original installer was specking 16 sq mm so don't understand why they would differ. Can't see that AC or DC would make the difference.

When you transparent did it have a crisscross pattern? 

Hi Sharpend,

As I recall it did which is why I thought it was like a reinforced pvc hose. It was milky white.

Like this? 
https://uk.rs-online.com/mobile/amp/p/sy-cable/0522541/?

Yes but was not clear like the RS example it was milky guess it might have weathered. The cables from the 16 panels a 4 kw system went into a junction box from which the feed to the outbuilding was connected. I recall it was not that large a diameter so wondered how much current it could carry. 

Sounds dodgy to me! DC cables cannot be left immersed in water, they fail after about 5 years - I've rewired entire solar farms for that fault. Now  a duct can be used, but it is essential to keep it dry whilst installing and seal the ends to prevent any moiture ingress. You can use SWA for the DC runs, and this can be directly buried in the ground, I don't think SY flex is suitable for this, and as  a cable isn't well recognised in the UK - we tend to use it for connecting machinery and not much else. Most solar farms are wired in 6mm solar cable with some pretty long runs, but solar cable is a different spec to SWA so he would need to check the spec and possibly up it a size to prevent unnecessary DC losses.

SY isn't suitable for burial or exposed sunlight. TBH they shouldn't be using it as it's not recognised by BS7671.

As for the original question if the SWA is earthed then there should be no issues with interference on the data cable, I would however run the data in a suitable armoured or toughened and screened cable.

Thank you chaps for beating me to it!! But very well put between you.  :Applaud

There seem to be a number of people that believe SY cable is acceptable for outdoor use ...... don’t know why

Murdoch said:

There seem to be a number of people that believe SY cable is acceptable for outdoor use ...... don’t know why

Click to expand...

It looks tough and looks armoured?

When its just screened and goes hard and cracks outside. I certainly wouldn't bury it.

Thanks for the great answers. Was correct to question this cable. I looked up the data sheet on this https://www.elandcables.com/media/38430/sy-control-flexible-cable.pdf and it does say it is ok in moist conditions but to protect from uv.  Sidney accurately stated it did not comply with BS 7671 but could the installer claim that as it connects the panels to the inverter only, that it would be exempt?