Industrial Unit Earthing Arrangement - Lack of

[sleepyfolk]

We’re in the process of replacing the 3 phase installation in our premises, the electrician that came said we should contact Western Power and request a PME, Western Power have said they can’t, we have also asked if they can supply a main earth terminal for us to connect to - they say they can’t.
Currently the only earthing arrangement we have is as follows:
Main bonding from cold water pipe goes to terminal in 3 phase isolator, 3 phase and single phase board has 10mm earth to isolator.
There is no earth from the isolator to anywhere, guess it just uses the SWA of the main incoming 3 phase cable that comes into the isolator.
Electrician says there should be a MET near our incoming supply with a 25mm earth cable from there to the isolator and I presume onwards to the new 3 phase board.
He did say something about using an earth rod if it was a house but thought it a bit impractical due to the size needed for our supply given we are on a concrete and tarmac industrial estate.
Can I have some advice please before I speak to him again.

 

[Pete999]

We’re in the process of replacing the 3 phase installation in our premises, the electrician that came said we should contact Western Power and request a PME, Western Power have said they can’t, we have also asked if they can supply a main earth terminal for us to connect to - they say they can’t.
Currently the only earthing arrangement we have is as follows:
Main bonding from cold water pipe goes to terminal in 3 phase isolator, 3 phase and single phase board has 10mm earth to isolator.
There is no earth from the isolator to anywhere, guess it just uses the SWA of the main incoming 3 phase cable that comes into the isolator.
Electrician says there should be a MET near our incoming supply with a 25mm earth cable from there to the isolator and I presume onwards to the new 3 phase board.
He did say something about using an earth rod if it was a house but thought it a bit impractical due to the size needed for our supply given we are on a concrete and tarmac industrial estate.
Can I have some advice please before I speak to him again.

Yes, get a different Electrician

 

[westward10]

Can you show a pic of your supply intake.

 

[sleepyfolk]

I’ll update with some pics tomorrow

 

[ipf]

Where's that 'main incoming cable' coming from?
Being swa….is it an authority cable or a sub main?

 

[sleepyfolk]

Pictures here hopefully, here’s the cut out and isolator in the distribution room which happens to be on the opposite side of the wall to our unit, and the internal view of our isolator switch in the unit.

 

[Nigel]

Is that not the earth coming in the bottom of the isolator with the black and red?

Looks small however.

 

[buzzlightyear]

sleepy hollow ,there must be a earth from the DNO to the met .
cause you can not religion the water services for a earth.

 

[westward10]

Is that trunking above the service head.

 

[buzzlightyear]

take that trunking lid off and look in side I bet their will be a earth from DNO.

 

[ipf]

Is that trunking above the service head.

Below it, for sure.

 

[Nigel]

There is no electrician is there?

 

[sleepyfolk]

The isolator switch that is open is in our unit, the 3P & N supply cable in the top is from the DNO isolator next door in the meter room, the grey bit on top of the switch is not trunking - it’s the cover for the rewireable fuses on the single phase board, the 3 phase board has been removed from our unit hence no cables on the outgoing RYB phases, the single phase tap off the yellow is to a single phase rewireable fuse consumer unit, the earth cable you can see in the bottom comes from said single phase consumer unit, which incidentally is where the main bond to the cold water pipe is, the hot water currently has none nor does the steel mezzanine floor.
Managed to get hold of our chap but he can’t get out until Monday so I’m interested in any advice before then, I know it’s difficult, here’s a shot of what’s in the unit - the 3 phase panel has now gone as it was snagging the stairs

 

[Nigel]

Best advice is to get an EICR done.

Best get a different electrician as I am not confident the one you are talking to knows what he is on about.

 

[Sparky Pat]

I find it very hard to believe that that the DNO can not provide you with an earth terminal on what looks to be a reasonably modern industrial building.

 

[Deleted member 26818]

DNOs don’t like to supply PME to metal framed buildings with multiple users.

 

[sleepyfolk]

It’s part granite and part breeze block, Western Power planning department said the network didn’t support it and it wasn’t their job to provide a MET, see what the man says on Monday I suppose and I’ll report back

 

[DPG]

Keep us posted.

 

[sleepyfolk]

Postponed until Monday 24th unfortunately, I will report back though, annoying when threads go unfinished!

 

[sleepyfolk]

Well took a little longer to get here but seems we’re running a 35mm earth cable through the wall and expanding an earth block that was hidden away in the distribution room, seems weird even back in the 80s that they just put a 6mm earth cable from the consumer unit to the isolator but guess it must have been ok back in the day!

 

[cprfenom]

Back in the 80's having an earth in any size was a bonus given what I see from time to time. Spin is right though in terms of Western Power, they will not generally add a PME to a steel from. Normally they advise a TT.

 

[davesparks]

Well took a little longer to get here but seems we’re running a 35mm earth cable through the wall and expanding an earth block that was hidden away in the distribution room, seems weird even back in the 80s that they just put a 6mm earth cable from the consumer unit to the isolator but guess it must have been ok back in the day!

Have you calculated the size of earth required?

 

[sleepyfolk]

I haven’t, the man in the know has, I thought he said 25mm before but he’s told me to get enough 35mm in to go through the wall into the meter cupboard where he’s connecting it in somewhere

 

[davesparks]

I haven’t, the man in the know has, I thought he said 25mm before but he’s told me to get enough 35mm in to go through the wall into the meter cupboard where he’s connecting it in somewhere

What size is the incoming supply? You’ve shown a 100A cutout, but based on that you wouldn’t need anything bigger than a 16mm earth and actual calculation would probably prove the 6mm to be ok.

 

[sleepyfolk]

ill check tomorrow and make sure I remembered the size right!