Has anybody used these matt-e products for EV charging points?

Any out of balance current on a three phase 4 wire system returns via the neutral conductor, not via the earth rod.

The earth rod is an important safety feature primarily to avoid danger from electric shock, A great many three phase systems are unbalanced and work fine.

Any out of balance current on a three phase 4 wire system returns via the neutral conductor, not via the earth rod.

Not during a broken CNE event - hence the OP is looking at an option from 722.411.4.1.

Banging in rods isn't likely to be a sensible option to keep things below 70V unless you've got remarkably low N currents, or the site is on a salt marsh. 

There are several makes of EVSE that offer ‘broken PEN’ protection of varying sorts.  Note that the type that works by measuring the L-N voltage (option iv) are only permitted on single-phase installations (since on 3-phase installations better results can be obtained by measuring against an artificial N derived from all three Ls).

The other option of course is to create a TT island for the charge point - although that means ensuring it's out of reach of anything connected to the TN earthing system - which isn't always easy.

   - Andy.

I see exactly where John is coming from. If the three phases were reasonably balanced, there wouldn't be a problem. I have looked at the same issue for myself and the loads are only sufficiently balanced when charging. That would be fine if the EVCP disconnected on completion of charging.

As I understand it, the physics allows comparison between the actual neutral current and the expected one. (Or is that voltage? ? )

I am still waiting for the market to mature and would also be interested to see other opinions.

I think for the balanced 3 phase option the consumer would need to be a single user on a transformer AND then  have a balanced 3 phase installation. 

Chris Pearson: 
 

…the loads are only sufficiently balanced when charging. 

It is common however to connect a car which only supports single-phase charging to a 3-phase charger, or occasionally a car which does support 3-phase charging via a single-phase cable. Clearly any design that assumes the car will draw a balanced current is flawed, so the balanced loads option is presumably only useful when the rest of the installation is both balanced, and hugely greater in load than the car. i.e. pretty much never.

Chris Pearson: 
 …the loads are only sufficiently balanced when charging. 

RichardCS2:

It is common however to connect a car which only supports single-phase charging to a 3-phase charger, or occasionally a car which does support 3-phase charging via a single-phase cable. Clearly any design that assumes the car will draw a balanced current is flawed, so the balanced loads option is presumably only useful when the rest of the installation is both balanced, and hugely greater in load than the car. i.e. pretty much never.

I suspect that in practice this is achievable only with a row of EVCPs along the side of a factory.

I suspect that in practice this is achievable only with a row of EVCPs along the side of a factory.

So what happens when just some of the charge points are in use? How can balance be assured? After all not all the batteries will be equally discharged or plugged in at the same moment, so they'll disconnect at different times as the cars become fully charged.

Or is the assumption that the EVSE load will be negligible compared to the balanced load of the factory?

   - Andy.

So, the OP has stated that 722.411.4.1 (i) balanced three-phase supply doesn't apply … and is considering the use of one of the devices in 722.411.4.1(iii) to (v) … noting that it may also be difficult to achieve 722.411.4.1(ii) additional earth electrode (the IET CoP for EV Charging Equipment Installation states this is also rarely practicable (see Appendix G).

Being a three-phase installation, the OP is looking at a device to 722.411.4.1(iii) … according to the manufacturer's web-site, this particular product doesn't require a measurement earth electrode, as per A722.4 item (b),  and is asking whether anyone has experience of this product?

AJJewsbury: 
 

I suspect that in practice this is achievable only with a row of EVCPs along the side of a factory.

So what happens when just some of the charge points are in use? How can balance be assured? After all not all the batteries will be equally discharged or plugged in at the same moment, so they'll disconnect at different times as the cars become fully charged.

Or is the assumption that the EVSE load will be negligible compared to the balanced load of the factory?

   - Andy.

Table J1 of the IET Code of Practice for EV Charging Equipment Installation shows the percentage unbalance required, and J4 (page 156) a “rule of thumb” for percentage unbalance, being:

So, perhaps more unbalanced than you might think?

BUT

John Peckham:

I think for the balanced 3 phase option the consumer would need to be a single user on a transformer AND then  have a balanced 3 phase installation. 

John's point is, that if a number of three-phase installations are supplied by the same combined neutral and earth (CNE) distribution main, then just checking the balance of the installation in which the EV charger is installed won't be guaranteed to protect that installation if a break occurs upstream of a number of installations and the one in question, if one or more installations upset the balance on the distribution main.

The important thing to remember about 722.411.4.1(i) is that it's the balance of the three-phases downstream of the broken PEN conductor in the distribution main, not either a single installation, nor the distribution main as a whole.

I suspect that in practice this is achievable only with a row of EVCPs along the side of a factory.

Or is the assumption that the EVSE load will be negligible compared to the balanced load of the factory?

Yes, that was my thinking.