Installing a 3 phase rapid EV charger?

[HappyHippyDad]

Im finding all those swirling conductors quite pleasing to the eye.

I thought you might Westward
It is rather nice isn't it.

 

[HappyHippyDad]

Yes the upstream device will need to be at a minimum Type A (assuming DC Leakage protection in the EVSE), otherwise Type B. Obviously also S-type (time delayed).

For example a number of EVSEs I installed for a well-known courier firm I replaced the upstream S-type RCCB for a Type A 300mA for the distribution circuit. This went to a switch fuse and then onto the DBs. I had triple pole circuit breakers in the DBs feeding four pole RCCBs. (It was a TT installation.)

Is there a reason why I shouldn't just bypass the 300mA RCD by using the Henley blocks upstream?
Meter tails into a separate enclosure housing all the bits I need.

 

[Risteard]

Just to add that obviously regardless of Earthing arrangements the RCDs must break all live conductors (just in case my earlier post is misconstrued).

 

[pc1966]

Something worth considering with three-phase charge points is that the phase sequence should actually be varied between units. So if there is a charge point connected L1-L2-L3 then an additional unit should be L2-L3-L1 or L3-L1-L2. This is to prevent them all pulling off the same phase where the vehicle is only capable of single phase charging. Obviously maintain the phase rotation though.

I had always assumed that EV chargers are like old 12V charger or many 3-phase UPS where they would use all phases to generate the DC for charging, but I guess they supply AC to the EV for that?

A very good point to spread the load over the phases!

 

[pc1966]

Is there a reason why I shouldn't just bypass the 300mA RCD by using the Henley blocks upstream?
Meter tails into a separate enclosure housing all the bits I need.

That would appear a better option if you can get a suitable RCBO or similar.

It might be the Matt:e with RCBO is suitable, but check what it needs up-stream. At the very least it would need an isolator, but you might be better with a 3PN switched-fuse with something like 40A-50A fuses to give total selectivity with 80-100A incomer fuses.

I see there is an isolator at the incomer which is great, but I would rather not have to totally shut down such a large installation just for any future EV problems being fixed.

 

[HappyHippyDad]

That would appear a better option if you can get a suitable RCBO or similar.

It might be the Matt:e with RCBO is suitable, but check what it needs up-stream. At the very least it would need an isolator, but you might be better with a 3PN switched-fuse with something like 40A-50A fuses to give total selectivity with 80-100A incomer fuses.

I see there is an isolator at the incomer which is great, but I would rather not have to totally shut down such a large installation just for any future EV problems being fixed.

Could you tell me why the Matt:e would need a separate isolator? It has a 5 pole mains isolator which could be used to isolate from the other electrics if a fault occurred.

 

[HappyHippyDad]

Given the cost of the matt:e and it being a farm could you not get a rod in using some machinery?
Like wise if its being used solely inside then use the pme.

Actually I don't think a rod will be possible. The charger will be housed in the meter room. The meter room has PME earthing terminals in it which will be simultaneously accessible with the charger (or tractor when it is being charged). Looks like it has to be Matt:e! Hopefully the charger has a PEN fault device already!

 

[Julie.]

...
Or, I could take the supply from the henley blocks to the left of the 300mA RCD which have no RCD protection? This seems better, as the cable from the Henly blocks to sub DB will not need RCD protection and I could locate it close to the henley blocks in the same room.

Yes, take tails from the Henry blocks into a kmf, swa to the charge point (assuming the charge point has integral rcd protection etc)
If the charge point doesn't have integrated protection, then instead of a kmf, use an rcbo, rcd/mcb, or rcd/fuse combination.

(Assuming supply is tncs or tns)

if TT then in both cases you would need a delayed rcd after the tails.

 

[westward10]

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[HappyHippyDad]

Yes, take tails from the Henry blocks into a kmf, swa to the charge point (assuming the charge point has integral rcd protection etc)
If the charge point doesn't have integrated protection, then instead of a kmf, use an rcbo, rcd/mcb, or rcd/fuse combination.

(Assuming supply is tncs or tns)

if TT then in both cases you would need a delayed rcd after the tails.

All sounds good, thanks Julie.
I shall hopefully read the spec of the charger on Monday.
As above, I don't think TT is an option as it will be simultaneously accessible to PME.