Earth spike query

[Guy]

I am working for a company installing pv at the moment, this weeks install has been on TNCS system and we are putting in an earth rod. When I asked why we were putting in a spike and not using the supplies earth the reply was along the lines of "if you lose the earth you will also lose the neutral". I understand that it is a combined earth and neutral but can someone clarify what he means please.

 

[steptoe]

:slap

well, firstly I dont think he has a clue what he is doing,

what exactly was he connecting to this spike?

AFAIAA it is not permissible to mix earthing systems in the same install.

 

[steptoe]

or was he making a localised PME system?

 

[Guy]

He must of been refering to bonding the array frame, that would make sense. We are finishing the job on monday so I will have a good nose about. Thanks for replies

 

[Guy]

thanks for that 'decision tree' link Canoeboy, I will have a look through that guide this weekend.

 

[Sidewinder]

I don't like that decision tree as if there is "any" "leakage" from the a.c. to the d.c. side and between the d.c. side and the array frame, most of which we have no control over and insufficient information from the manufacturers to decide on the appropriate action, then any diverted N current which is "normal" or is generated in the event of a fault would end up on the array frame.

Mind I had to guess a LOT about the decision tree as I could not read the text!

 

[Sidewinder]

Nope sorry mate, failed search at this end!

 

[Sidewinder]

Got it.

What a load of tosh that is, no wonder the solar PV market is in the state it is if that is the quality of the guidance given.

It takes no account of simultaneously accessible exposed or extraneous conductive parts which are legitimately connected to the TN-C-S (PME) earth terminal of the supply when the array frame is bonded to a rod, which is a different earthing system, thus creating a possible shock risk between these and the TT earth of the array frame.

:slap

 

[Jono Pashley]

Most the monkeys ive come across lately cant think tho they can only follow blindly...did manage to get one install sorted where they had made a hash of it(backfed RCD) but theres only one of me and so many unqualified monkeys it seems endless.

 

[kme]

And now I`ve been asked to go do Inspect & test on a 50 acre, 20,000 panel "farm" next week!!!!!

dosh nets at the ready, `cos THAT will cost a bit!!! :slap

 

[Sidewinder]

KME,

 

[Jono Pashley]

And now I`ve been asked to go do Inspect & test on a 50 acre, 20,000 panel "farm" next week!!!!!dosh nets at the ready, `cos THAT will cost a bit!!! :slap

Sounds more fun than what ive got on! I think im slowly being turned into a plumber by this new company....

which at a guess will be permanant repair to a leaking roof, change some taps out, fix a toilet. THEN just maybe they will get me permission to do some actual electrical work..