Earthing the Array - Practically

Worcester · May 24, 2011

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 · May 25, 2011

Worcester said:
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 · May 25, 2011

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 · May 25, 2011

"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 · May 25, 2011

@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'.

[ElectriciansForums.net] Earthing the Array - Practically

Earthing the Array - Practically

Worcester

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SolarCity

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BruceB

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dansk

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Worcester

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