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single phase PEN protection within three phase supplies

David Slate

Good Morning all,

We have used MATTe devices many times for PEN protection when the charger has no inbuilt protection. 

The MATTe devices for single phase rely on protection settings as described in indent (iv) of 722.411.4.1

MATTe sate on their website the following:

 BS 7671 does not permit a protective device as described in indent (iv) of Regulation 722.411.4.1 to be used to protect single-phase charging equipment in three-phase installations.

Quite a few devices rely on ident (iv) but other than MATTe non of them highlight this issue?

What im after if anyone would be so kind, is an explanation as to why this is the case, and why a single phase MATTe can be used on a single phase supply on a terraced house where next door will be (most likely on a different phase of the same supply) but not within a 3 phase installation.

I have an idea it is due to unbalanced 3 phase loads  and voltage to neutral on one phase can appear to be ok masking any loss of neutral should it occur. But a better explanation would be great!! maybe even links to a diagram to be able to show to project managers!

Parents
  • 0

    I have been to look at a job today,  a shop with a three phase supply and an E7 three phase meter is going to split to create two shops and a flat. 

    So I need to contact WPD to request three single phase supplies for the three new premises to be supplied from the existing three phase head, both shops really need to have E7 supplies for storage heaters, the flat has a gas supply, but I'm thinking it should have an EV charge point in its parking bay.

    I can't see that this could be considered a three phase installation if the three single phase supplies are installed from the same head. 

    Would there be any issues regards using open PEN protection for one or more EV charge points?

Reply
  • 0

    I have been to look at a job today,  a shop with a three phase supply and an E7 three phase meter is going to split to create two shops and a flat. 

    So I need to contact WPD to request three single phase supplies for the three new premises to be supplied from the existing three phase head, both shops really need to have E7 supplies for storage heaters, the flat has a gas supply, but I'm thinking it should have an EV charge point in its parking bay.

    I can't see that this could be considered a three phase installation if the three single phase supplies are installed from the same head. 

    Would there be any issues regards using open PEN protection for one or more EV charge points?

Children
  • 0 in reply to Sparkingchip

    I'd imagine on the basis of each phase being separately metered then you have no option than to fit single phase PEN protection unless a 3phase landlords supply remains that could be utilised 

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