Array bonding needed?

[moggy1968]

Is that a serious remark .................... your telling me that it is irrelvant how you are trained

yes it is, yes I am. To a point. As before, lets stay on topic. Start a seperate thread if you want to discuss this.

 

[wstevew]

So would I be right in saying that most think bonding isn't required but some are doing it because the current DTI decision tree says so?

Im not sure why SMA suggested getting the installer to make sure the array is bonded when I asked about the 601 error (unless they think a difference in potential somewhere would be detected as DC current by the inverter). I believe the arrays are not bonded.

Anyway the 601 events which happen approx twice a week up until now were before and after feed in. I now think this may be a coincidence as I was up and out earlier this week as I have been working away and there was a 601 error around the time I was getting ready (i left at 6am, a while before feed in).

The only things electrical I would have used would have been lighting. My suspects at the moment are.

Led lighting 6 x 3w mr11 running off 3 12v 1a DC psu (2 lamps on each psu)
Led lighting 5 x 6w mr16 GU10 240v

Illuminated Bathroom mirror 140w halogen with wound transformer (has a pull cord I need to replace as one set of contacts are going bad, pull cord is on the 12v ac side).

 

[grandfortune]

DOnt just think of people hanging out of houses and such, there are other considerations to think of, Its an important subject that needs some clarity, Nice little report here, long winded but pictures alone look good, remember shock date results are based on 60Hz.


http://www.mikeholt.com/files/PDF/firefighterSafetyPV.pdf

 

[Vegelen]

SMA recommend that solar panel rails are earthed when using SMA inverters without a transformer. i.e TL's.

Quote from an email received from Mark Ryder at SMA:

"SMA do suggest that you earth the solar panel rails when using inverters without a transformer.


Kind regards, Mark Ryder, SMA UK"


The Importance Of Earthing Solar Panels:

Earthing solar panel frames - Energy Matters

The reason to earth solar array frames installed with transformerless electronic

inverters, may be for functional operational reasons, not just for safety concerns.

I have seen evidence of a solar system with SMA 3000TL perform differently relative

to another local system, after it was earthed 10 days after installation.

Earthing the array frame changed its performance relative to another local system.

 

[JulianC]

I had/have a DTI document which provides guidance and explanations to the content of v2 of the DTI PV guide. Unfortunately I can't find it at the moment (and may not have liberated it from my previous employer). It did go into the reasons why they required an array frame to be bonded if using a transformerless inverter. Bear with me on this as my memory is sketchy, but it was something to do with the simultaneous occurance of a fault on the inverter sending AC to the array and a fault with the array or DC wiring presenting AC to the array frame work, coupled with the likelihood of some chap up an aluminium ladder that is connected to earth touching said array frame. Don't quote me 100% on that but it was something equally as convoluted and unlikely.

 

[Gavin A]

well if that's the problem they're trying to solve, I'm not too concerned as I'd expect that sort of a fault to trip the RCD on the AC side 99.9% of the time, and we've been installing an individual RCD on each AC circuit on virtually every install we've done.

it'd also require multiple fairlures within the inverter, and the inverter remaining stuck on the on position - something I can't see happening for anything other than a lightening strike.

It's also solved by instructions to switch the ac and DC isolators off before going on the roof.

 

[moggy1968]

Hmmn
thats a covulted set of circumstances bearing in mind the regs require protection against single fault conditions

 

[steve Leese]

http://www.greenhippohut.com/sites/default/files/capacitive-discharge-currents.pdf Has this any bearing on what you are discusing, as reguarding the earthing of the array.

 

[yellowvanman]

Spoke to someone who is influencial in the MCS arena and in conversation asked him about bonding of the array for TL inverters and he told me to read the new version of GN7. Yet to read it but lead to believe it states no need to bond.

He also when onto to say the DTI guide is 'guidance' only and then started on about lockable ac isolators, dc isolators when you've got integral isolators in the inverter and type A RCDs!

Apparently the new DTI guide will reveal all!

 

[rich.250]

Spoke to someone who is influencial in the MCS arena and in conversation asked him about bonding of the array for TL inverters and he told me to read the new version of GN7. Yet to read it but lead to believe it states no need to bond.

He also when onto to say the DTI guide is 'guidance' only and then started on about lockable ac isolators, dc isolators when you've got integral isolators in the inverter and type A RCDs!

My point exactly. These publications are only guides. BS7671 holds all the answers for the requirements.
I don't see the need to bond them. Unless maybe they require a functional earth. This is earthing not bonding anyhow.
This would be to the MET and never to an electrode.
All the confusion seems to be caused by people listening and trusting too much to what there told and not checking for themselves.
Good to see everyone on here is trying to get this confusion sorted

 

[TedM]

It's mandatory to comply with all the double-ticked items in the DTI Guide in order to comply with MCS rules - or are MCS now saying that they can bend their own rules? Also the single-ticked items are mandatory unless you can show good reason for a variation.

This is all in MIS 3002 v2.1 para 4.2.

For the purposes of this standard, all double-ticked items in the DTI guide are mandatory. Compliance with all single ticked items is also expected unless reasonable justification can be given.

But having said that there are no ticks, single or double, against the tree diagram itself.

 

[babba]

Well Ted you just set this thread off AGAIN...I hope you can sleep tonight...

 

[Gavin A]

But having said that there are no ticks, single or double, against the tree diagram itself.

well if there's no ticks then there's no ticks.


also, if NAPIT send a sodding gas engineer out to assess us again, and try to get me to bond the frame to the MET on an SB1200 inverter with full galvonic isolation just because it's near a skylight.......:66: