500kva substation earthing , any qualifications needed ?

[JD6400]

We have just taken on a new client who is extending their industrial park.
Their previous electrician had been helping with the install all of a totally new feed and 500 kVA onsite substation by UKPN.

I received a phone call from the client last night asking if I had tested off , or the previous electrician had tested off the earthing arrangements , which have been installed by both himself and his previous electrician before the substation had been built.
The previous electrician being a local , one man band . ( All be a very good and knowledge one from what I have seen on site )
This was the first I had heard that he had carried out the earthing himself.
We have always engaged outside HV contractors for this task previously for the very least peace of mind let alone the legal responsibilities.

I have always assumed special qualifications are required let alone specialist insurance's if carrying out and signing off this type of work?

What do others think ?

 

[plugsandsparks]

Is it a "Hot Site" ?

 

[JD6400]

Hot site ?
This is exactly why I always use the HV boys ?

 

[plugsandsparks]

Sorry :A site containing HV equipment where the rise of earth potential under earth fault conditions can exceed the limits of 430V or 650V, as applicable. The 650V limit only applies where the power system has an operating voltage of 33kV or greater and main protection is designed to clear earth faults within 200m.

The DNO will have stated whether its Hot or Cold, the earthing design has then to be done to ensure rises in earth potential due to MV/HV faults dont cause a rise in the LV earth system. Makes sense really but its a function of the ground impedance.

It could be that the DNO have done the HV side earthing, ( you can easily check), and also check if its classed as Hot or Cold. After that then the LV system is designed.

The DNO have a great library for Sub earthing, its not rocket science, but also its not just ramming a rod in the ground either. There needs to be a design, onsite soil measurements and testing records.

Funnily enough i am just going through this with NPG and a MV Subcontractor. Its all green field so dont have issues with distance and ground conditions (but you might)

 

[Rockingit]

I feel an education coming on....

 

[Petej999]

We have just taken on a new client who is extending their industrial park.
Their previous electrician had been helping with the install all of a totally new feed and 500 kVA onsite substation by UKPN.

I received a phone call from the client last night asking if I had tested off , or the previous electrician had tested off the earthing arrangements , which have been installed by both himself and his previous electrician before the substation had been built.
The previous electrician being a local , one man band . ( All be a very good and knowledge one from what I have seen on site )
This was the first I had heard that he had carried out the earthing himself.
We have always engaged outside HV contractors for this task previously for the very least peace of mind let alone the legal responsibilities.

I have always assumed special qualifications are required let alone specialist insurance's if carrying out and signing off this type of work?

What do others think ?

Dunno about quals, I do know that just to operate the switchgear you need to become an AP Authorised Person, there are strict rules and regulations to be adhered to,
HV installation need an AE authorising Engineer to supervise and operate the HV side, your client needs to think twice about asking you questions, and employ an Engineer to supervise and operate this HV system.
What voltage is the system running on, does the HV system / sub station feed a Ring or Radial system, which ever not something to be taken lightly, your client is treading on dangerous ground if he doesn't employ an Engineer to supervise this new installation.

 

[James]

I feel an education coming on....

Most electricians are (including myself) unsure of the requirements and regulations involving HV

My take on it is along the lines of Don't mess with what you don't fully understand.
I have seen the damage done to a couple of people who were lucky enough to survive a HV accident and neither of them would have qualified for a beauty contest.
one of them was a friend for many years and eventually I was one of his pall bearers after his injuries both mental and physical led him to take his own life.

I have a lot of respect for the people who are trained and knowledgeable in the field of HV and have no desire to meddle in their domain.
however, I am always keen to learn and if anybody wants to explain the details of it, I will happily absorb the knowledge.

 

[Rockingit]

Most electricians are (including myself) unsure of the requirements and regulations involving HV

My take on it is along the lines of Don't mess with what you don't fully understand.
I have seen the damage done to a couple of people who were lucky enough to survive a HV accident and neither of them would have qualified for a beauty contest.
one of them was a friend for many years and eventually I was one of his pall bearers after his injuries both mental and physical led him to take his own life.

I have a lot of respect for the people who are trained and knowledgeable in the field of HV and have no desire to meddle in their domain.
however, I am always keen to learn and if anybody wants to explain the details of it, I will happily absorb the knowledge.

I think the key thing with this, as with so many others, is to recognise the difference between having an enquiring mind that likes to learn things and 'knowing enough to be dangerous', as the old expression goes. Simply because I absolutely understand how a wing section works to create lift and also the mechanics of how a jet turbofan engine runs does not make me fit to fly a 747.

 

[plugsandsparks]

The thing is, the previous electrician ended up with the responsibility of the earthing. Assuming this is just the LV side, then it looks like the DNO have put that responsibility to the client.
What would be useful for the OP is the original DNO services offer to work out who is supposed to do what.
e.g Have DNO just provided a metered MV supply ? - Have they provided an LV supply with the point of client connection inside the Sub ?
One way or another the LV needs to be properly earthed.
No reason to run away just yet, OP needs more info regarding lines of responsibility

 

[JD6400]

Thanks for the responses , had Covid for the last week so heads a bit slow at the moment .

It is a mixed site with a full equestrian yard / house and large wedding venue up one end coming through to existing units ( 30 or so ) and a new 21 unit development ending with an existing 5000 ton or so grain store which is in the middle of being doubled up.
The substation is in the middle of the yard that transitions from the units to grain stores.
UKPN have laid on a new feed at least a mile or so underground in to the new substation.
This has been an ongoing project apparently for well over a year.
I say UKPN , he has subbed out the contestable works to UKPS .
Out of the substation and into a new mains cupboard / building they have 1 X 217kVa 400a connection and 3 X 69kVa 100a connections.

Edit more to come , posted too soon by accident

 

[JD6400]

We were going from the new mains room and bolstering existing supplies and running a new one into the development of 21 units.
Along with the new grain store and all the existing works.
The phone call yesterday day came about because the other electrician has gone to ground now he's been asked for the certificate for the earthing.

I was surprised that it had not been carried out by a specialist company which got me wondering if it actually had to be ?

 

[JD6400]

As I understand it , the earthing and test that he is referring to is for , and what the new substation is sitting on .
I believe it was a nest of tape with rods at either corner.

 

[Lister1987]

Would a grain store come under any Ex considerations? Or would that only apply to a plant processing the grain? Last thing you want in a cloud of flour is a spark.

 

[JD6400]

They are only flat stores at the moment but we will designing as appropriate for that side .

 

[MJPD29]

Is it a "Hot Site" ?

Sounds like some sort of adult material