usual question - pv array earthing!

[edexlab]

I met an installer from an established firm when we started Pv and he'd been to the same job twice to replace module cables which had been chewed by squirrels ,and were causing some arcing every time the wind blew ,these cables were cable tied but some had also been attacked by the tree rat (squirrel) ,anyway the customer was an animal lover until he got the bill , he then hired a couple of blokes to come and shoot the offenders and has'nt had any problems since.

 

[malcolmsanford]

Do any of the other PV guys on here have experience of vermin attack.

I have to be honest and say though far from experienced in PV installation, every one I have seen or done the panel tails are just basically cable tied to the array frame and left un-protected. As edexlab above pointed out, should the tails now be protected under regulation 522.10. Do any of the PV guys protect the tails from fauna and if they do, it would be interesting in how they do it.

 

[paulsamuel1984]

I do not provide any mechanical protection for the cables, but cable tie to the array frame. I have not had any vermin issues (as yet!) with any installs. This has raised some interesting points regarding bonding. As earlier stated, under the correct circumstances I have not provided any earthing / bonding for the dc, including connection to earth or any bonding of the frame.
But as a result of the above, I would be interested to know how people protect the tails to further justify not bonding the frame.

 

[SolarCity]

Bonding the rails together takes 10 minutes. We've had many discussions on site about it and we do it on all our installs now (although to be fair, most of our installs are on TL inverters now anyway)

 

[malcolmsanford]

IMO as the installation is a class II type then the frame is not an exposed conductive part and therefore does not need earthing, agreed if the invertor does not have AC/DC speration in the form of a transformer that is a differnt matter.

The same for bonding, if the frame is floating it can not introduce a potential and therefore is not an extraneous conductive part and should not be bonded, as there is a possibilty by bonding is making the frame prone to become LIVE during a fault within the equipotential Zone.

So if there is in the designer opinion a chance of fauna attack on the exposed panel tails then you have to protect them by regulation 522.10.1 and either of the 3 options. Well relocating can not be one, so it will have to be mechanical protection either in the form of a sheathed metallic cable which would not be cost effective or conduit/trunking which IMO would be the easiest.

 

[malcolmsanford]

I deal with inverter sales both here in the the UK and also USA. As it stands in the UK if the inverter has a transformer in it you don't need to bond the rails to earth. If it doesn't (TL) you do.
In the USA under UL regulations - ALL PV installs have to earth the frames - regardless of the inverter type. Surely they are doing this for a good reason?

Think of it this way. Faulty panel, engineer on aluminium ladder in the rain climbing on roof and holding the external tv ariel mast to steady himself. What could possibly go wrong?

Ken

There is a very goood reason for this, they have a completely different earth arrangement to the UK ......

As for your scenario.....................nothing as the panel is a class II piece of equipment which relies on double insulation for protection, the TV mast ariel is just a bit of metal and will have no way of being able to introduce a potential .................

 

[Worcester]

TV aerial mast usually (unknowingly) connect to earth.

Screen on TV cable is connected to mast, and also to the TV/Digibox, Digibox/TV chassis connected to earth.

 

[malcolmsanford]

is your digi box and TV a class I piece of equipment??