Earthing for an EV Charging Point

[uksparks]

I know and I accept that I am probably being guilty of doing what you suggest.

Ok ok so I am coming to terms with the fact that I'm going to have to put earth rods in.

without trying to sound like I don't want to do that, do you feel it acceptable if I measure the Ra of the steel work that is connected to the MET to satisfy the requirement of the additional earth rods, this is in the basis it falls lower than that of the calculation of 3 ohms etc.

i am sure you would agree that there is little point in putting rods in if the steel is doing just as good a job.

 

[uksparks]

I do very much appreciate all the feedback and support on this, it's a newish area for me that I'd like to get more involved with, so would like to get on on the right foot.

 

[spark 68]

I think it is a newish area for most of us

Previous to this thread I had only a cursory look at AMD 2, no where near the more in-depth look since

 

[Knobhead]

I have an Excel spreadsheet as well. Wanted to show the way to calculate it though. Either way its the same answer

Here you go

I[SUB]n[/SUB] = √((I[SUB]a[/SUB]²+I[SUB]b[/SUB]²+I[SUB]c[/SUB]²)-((I[SUB]a[/SUB]*I[SUB]b[/SUB])+(I[SUB]a[/SUB]*I[SUB]c[/SUB])+(I[SUB]b[/SUB]*I[SUB]c[/SUB])))

I'm glad someone has made use of the spreadsheet.

 

[spark 68]

Ok ok so I am coming to terms with the fact that I'm going to have to put earth rods in.

without trying to sound like I don't want to do that, do you feel it acceptable if I measure the Ra of the steel work that is connected to the MET to satisfy the requirement of the additional earth rods, this is in the basis it falls lower than that of the calculation of 3 ohms etc.

i am sure you would agree that there is little point in putting rods in if the steel is doing just as good a job.

My stance here is that if you are going additional Earth rods to the PME MET then they should be certified separately and as standalone, others may differ here.

Another option might be if you can get access to the re-bar at the concrete base of the building and get a reading from here, others on here have more experience of Ufer Earthing than me.

I think it would be virtually impossible to take a reading of the building's steelwork alone because of the various difficulties of separating the services and parallel paths, hence my stance earlier wrt separate rods.

Some might think this doesn't, matter but my own opinion is that how can you be sure it meets the requirements for the exemptions you are proposing using if you cannot accurately quantify it ?

 

[uksparks]

Just a side note to this, I have just been speaking with a friend of mine who has been a spark for more years than I am old and he has been looking at the new section 722.

Having had a good chat with him, he is suggesting that the buildings Ra should be very good and that if I run a 16mm earth from the charge point and bolt it on the steel work of the building and label it etc, this should help satisfy the regs.

Like I say, this is what he said, anyway, I am considering my options and way forward with this and will have a think of the best way to approach it.

 

[uksparks]

My stance here is that if you are going additional Earth rods to the PME MET then they should be certified separately and as standalone, others may differ here.

Agree, if it was used a a TT then yes it should totally comply, I accept this.

Another option might be if you can get access to the re-bar at the concrete base of the building and get a reading from here, others on here have more experience of Ufer Earthing than me.

I think it would be virtually impossible to take a reading of the building's steelwork alone because of the various difficulties of separating the services and parallel paths, hence my stance earlier wrt separate rods.

I can get access to the verticals that are bolted to the ground, I can access them but probably 2m up from the floor, this is the closest I can get.

Some might think this doesn't matter, but my own opinion is that how can you be sure it meets the requirements for the exemptions you are proposing using if you cannot accurately quantify it ?

The only service to the building is water which comes in as polythene not copper, so its safe to say that the only path back to earth will be via the steel if the main earth is disconnected. I agree with what you say.

As much as I hate to say it, this installation might be a learning curve ready for the next one.

 

[Silly Sausage]

UKS, you say this is a new building; where, how far away and how old is the supply to it?

I've only read snippets of these two epic threads, I'm going to have to get a crate in and sit down and have a good read!

 

[uksparks]

It's a brand new building less than 6 months old on a brand newly developed commercial area. All brand new.

im just looking at construction regs and ground rods and plate requirements on steel frame buildings.

its a couple of fantastic threads.