Array bonding needed?

[malcolmsanford]

What amazes me here is the complete lack of electrical knowledge in this

When I did my PV course and this came up, and the tutor said yes you bond back to the MET unless it is PM-E, which it wouldn't be, but I let it pass it is TNC-S in the installation, when it is TNC-S you stake it .................what!!!!

Why ........because the DTI say so....ahhhhhh so if you had a stainless steel boiler flue that could be touched while also touching the frame, that flue is obviously connected to the boiler, pipework is connected back to the MET via main equipotential bonding, and you then bond your frame to an earth stake ................how safe is that when you have 2 potentials within touching distance on the roof ...................blank stares we shall move on

I have yet been given an answer to this, though I know what will happen, if you had a fault within the installation and you were in contact with both potentials..................

Again this is another of these belt and braces decisions by someone, who believes that because it is a TNC-S system, there is a danger of a lost neutral, so it is do it this way and there is less risk, rather than doing what is right and having the competent electrician design and install what is the correct installation.

I have no problem if the DTi want us to bond to a stake if there is a TNC-S system, providing that TNC-S is not on a roof already .................but I would rather them say regarding bonding that the qualified, competent designer should assess each installation as he sees it, and with the information given by the manufacturer, design, install and test an installation suitable for conditions, but then I'm assuming to much perhaps.

 

[rich.250]

I couldn't agree more malc. There doesn't seem to be knowledge behind these statements. Just 'cos it says so' lol.
There a lot of things that bug me with a lot of pv installs at the minute.....
Another is disconnection times.
Feeding into a Rcd way on a cu and then completely destroy the disconnection times for the property or a number of ccts with our even knowing what they are doing is wrong.........

 

[SolarCity]

I couldn't agree more malc. There doesn't seem to be knowledge behind these statements. Just 'cos it says so' lol.

Well I do 'know' that is 'says so', so I suppose there is some knowledge behind it. As soon as you're writing the guidelines that I'm expected to adhere to then I suppose I'll be doing it your way.

There a lot of things that bug me with a lot of pv installs at the minute.....
Another is disconnection times.
Feeding into a Rcd way on a cu and then completely destroy the disconnection times for the property or a number of ccts with our even knowing what they are doing is wrong.........

A pretty general statement. Most of the installers on this forum know that that is bad practice so to I don't really see your point.

 

[rich.250]

Well I do 'know' that is 'says so', so I suppose there is some knowledge behind it. As soon as you're writing the guidelines that I'm expected to adhere to then I suppose I'll be doing it your way.



A pretty general statement. Most of the installers on this forum know that that is bad practice so to I don't really see your point.

I wasn't having a go at anyone in particular.
Yes a lot of people know, just saying that shouldn't it be an important part of the course??
It's not just bad practice. It's dangerous. Say you have a TT with Rcd upfront in the cu. then you had a pv cct in the spare way at the end. Now instead of a 0.2 sec disconnection time. It's probably 5secs depending on equipment used.
You may aswell throw the Rcd in the bin and fit a main switch LOL.
Like I said not pointing fingers just see a lot of it....

 

[rich.250]

Also it is all in bs7671. So follow those guidelines

 

[SolarCity]

I wasn't having a go at anyone in particular.

Nope, just the industry in general

Yes a lot of people know, just saying that shouldn't it be an important part of the course??

Of course, as should plenty of other stuff. So should a lot of stuff on the 6 week sparky courses.

Say you have a TT with Rcd upfront in the cu. then you had a pv cct in the spare way at the end. Now instead of a 0.2 sec disconnection time. It's probably 5secs depending on equipment used.

Like I say, most of us know this already. So I ask again, what is your point? It doesn't seem at all relevant to the current discussion.

You may aswell throw the Rcd in the bin and fit a main switch LOL.

That truly is a rib tickler.

 

[malcolmsanford]

Solar I think what Rich and I mean is that unfortunately the electrical industry as a whole as gone through this "belt and braces" approach to things, and if i'm honest I think PV is perhaps on line with the much maligned Electrical Trainee.

I did my course in May 2010 and to be honest it was pitiful and frightening the guys on it, that were roofers and plumbers, and were passed to be competent in all aspects of PV installation, and some of the basic lack of electrical knowledge on the forum as a whole is terrible.

Now the course may have improved, but in all honesty you just read this thread and some her can't determine whether it is earthing or bonding, and the sad thing is those who don't know what it is, don't think it matters, after all it does the same thing and goes to the same place .....................

The electrical industry as a whole and domestic and PV particularly does suffer it's fair share of poorly trained incompetent installers.

This is my worry, when an organisation feels it needs to compensate for this poor training, by adopting a belts and braces approach to an industry, it is going down the road to creating more problems. They are covering over cracks in an industry that unfortunately is in it's death throes.

The lads in our industry have won a significant battle over BESNA, but we are going to create an industry so fragmented in regards to trained and competent sparks in commercial/industrial and A N Others in domestic. There will be incidents happening IMO with this belt and braces approach, you can not compensate for poor training with a one size fits all appraoch, not in our industry.

 

[SolarCity]

I think in general I'm largely in agreement with you, Malc.

Unfortunately, with regards to this issue PV installers must go by the decision tree - whether they like it or not.

As for bonding and earthing, I know what you mean. The Dti guide itself refers to it as both bonding and earthing in different instances which confuses people even further. Bonding IS, for reasons that escape me, badly misunderstood.

 

[rich.250]

Yes malc. That was my point. Thanks for explaining.
If some installers don't know about disconnection times and earthing and bonding. They shouldn't be doing it!!
Like I said solar, I'm not having a go at you or the industry (cos I'm in it too)
Just as you said the Electrical Trainee. Or 5dw in some cases lol.
I know this probably isn't relevant to 90% of forum members.

 

[SolarCity]

If you read most of my posts, I have often moaned about the lack of electrical expertise in this industry.

A lot of the installs appear to be installed as kits with the electrician having no input whatsoever. They are handed an inverter, some isolators and told what to do.

The survey and design stage appears to be no more than 'will it fit?', 'where can I buy a kit' and 'how much shall I charge'.

 

[rich.250]

That sounds like the surveying they done on a rental property of mine some 5years ago. LOL

 

[malcolmsanford]

I think in general I'm largely in agreement with you, Malc.

Unfortunately, with regards to this issue PV installers must go by the decision tree - whether they like it or not.

As for bonding and earthing, I know what you mean. The Dti guide itself refers to it as both bonding and earthing in different instances which confuses people even further. Bonding IS, for reasons that escape me, badly misunderstood.

Well mate that just about sums it all up .................. we have a guide written by the looks of things by civil servants and not a technical input in sight.

Bonding in misunderstood because the training these guys receives is pitiful. We are no longer training guys to teach them an industry, but to pass exams and assessments so that they can stumble along in the industry and hopefully not kill or injure someone.

I sometimes wished we had more incidents in our industry, a few more deaths or a few more properties burnt down, may just may convince the bureaucrats that what they are doing to it is criminal. Yes domestic is not rocket science a few cable pulled in here and a few bits and bobs and there you go, bit like a nurse or a doctor taking your blood pressure, whack on a cuff, read a screen and there you go .....high blood pressure, but isn't it wonderful that that doctor will know why it's high, and what he can do to decrease it, that is called training, we just have guys that know yes wire A goes into equipment B not not a clue why

 

[Earthstore]

I could not agree more with Malcolm, I am not a sparky, but my background is more mechanical, if you get an electrical problem on a car, it is far more complex, 108 tiny wires to an ECU and you have to find the fault, so you have to understand how it works, to then work out why it does not.
It is sad that I appear to have a better understanding of PV systems than some sparky's (only some), and they are installing it.
The bureaucrats do seem to believe that if you can fill in reams of paper work, then the customer will get a quality install, I am waiting for the sad day when someone does get hurt.

 

[rich.250]

I don't think the people you talk of earthstore are actually electricians.... Else they could work out what is right and what is wrong.
Ok yes, training they receive is a big factor, but as a professional should it not be on your shoulders to ensure the job you do is correct and up to current standards??

 

[rich.250]

Malc, the doctor nurse description perfectly sums it up.

 

[Earthstore]

Thank you, Professional, I like that,
I do not install, I will help if need but only as an assistant, when I have sold a job, I kind of project manage it from beginning to end, I check that all work is to a high standard, from mounting of the panels through to the wiring, I work with the installers to make sure everything is right for the customer, so that I am proud of the work that I have sold.
I have learnt so much from this forum, as there are many experts here, so I am aware of how it should be done.
The PV industry has now got so complex, but I try my hardest to keep up with it all.
Pride is a word that appears to be lost in modern society, but some of us still have it.

 

[moggy1968]

strange how when managing projects it's the time served apprenrice trained electricians who have tried to insist everything has to go on an RCD under 17ed, and that it's fine for the PV to go on a shared RCD, and aren't prepared to listen to anyone telling them different. At least the short course guys tend to be willing to listen and learn, unlike the arrogance of some time served sparks.

Now, shall we stop making sweeping generalisations and chucking insults at people and get back to the topic.

 

[Earthstore]

Sorry...
So should an array be bonded and earthed???

 

[Gavin A]

What amazes me here is the complete lack of electrical knowledge in this

When I did my PV course and this came up, and the tutor said yes you bond back to the MET unless it is PM-E, which it wouldn't be, but I let it pass it is TNC-S in the installation, when it is TNC-S you stake it .................what!!!!

Why ........because the DTI say so....ahhhhhh so if you had a stainless steel boiler flue that could be touched while also touching the frame, that flue is obviously connected to the boiler, pipework is connected back to the MET via main equipotential bonding, and you then bond your frame to an earth stake ................how safe is that when you have 2 potentials within touching distance on the roof ...................blank stares we shall move on

tbf to the dti guide, this was a problem with your tutor, not the guide.

The guide says bond to MET if it's in the equipotential zone to avoid this issue.

 

[saint]

Earthed no never. Bonded no but for some reason we are told we must. This will change soon surely.