Earthing the Array - Practically

[Worcester]

Thanks to all that have contributed, seems to me that BiggsSolar and Markc are suggesting 'currently adopted best practice' until specific guidance comes out (if ever)

To summarise, currently adopted best practice is:

1) Bond each rail.
2) Bond across rail expansion joints.
3) Single earth cable (10mm2) to appropriate earthing point as per guide.

How to bond:
Connections: Use the fixing rail mountings, a dedicated bolt to the rail (stainless steel), or an external earth bonding strap.
Bonding method: 10mm2 Braid or equivalent

p.s we put warning stickers on EVERY panel saying 'LIVE DURING DAYLIGHT HOURS' - does anyone else?

Not sure as I'd want to put a sign up saying "Isolate before working on the roof" otherwise where would you put it, and how many places would you put it... putting by the isolators is a waste of time, and a big sign on the roof?

 

[SolarCity]

p.s we put warning stickers on EVERY panel saying 'LIVE DURING DAYLIGHT HOURS' - does anyone else?

Again, we had exactly the same conversation yesterday! My colleague thinks we should be putting these on each VISIBLE side of the panels and a "Do not disconnect under load" sticker. I disagreed as I don't think it is necessary. I think it is fair to say at the very least that anyone messing with the panels would switch off the DC isolator. This removes any load and therefore 99% of the minimal risk when unplugging the panels.

 

[BruceB]

Well I think I agree with you Worcester that what you describe would be best practice if you have to bond the array. For a number of reasons I think it is over the top and I also know the DTI guide makes some incorrect statements about PME which lead it down what I believe is an unnecessarily pedantic path. I have only been on this board a couple of months and have a faint recollection that someone here mentioned around the time I joined that the DTI guide was being updated. Anyone know?

One other point about best practice - if you are going to do all the bonds you mention above then they are de facto part of the main protective bonding regime. Therefore every joint must be labelled with a "Safety Electrical Connection - Do Not Remove" label in accordance with 514.13.1.

Regards
Bruce

 

[dansk]

"p.s we put warning stickers on EVERY panel saying 'LIVE DURING DAYLIGHT HOURS' - does anyone else?"

We dont do this - not to say its a bad idea - but anyone working on the PV system should be suitalby qualified and therefore know there "live during daylight", and anyone not; should not be touching with things they dont know about.

 

[Worcester]

@BruceB

if you have to bond the array

Agree entirely.

every joint must be labelled with a "Safety Electrical Connection - Do Not Remove"

good point

@dansk, The problem is you get roofers, builders, TV aerial fitters, Sky etc all crawling around there, who may know nothing at all about 'that PV stuff'.